10/12 Electronics

Please add updates@feedmyinbox.com to your address book to make sure you receive these messages in the future. Electronics How Plasma Displays Work October 11, 2009 at 10:15 am For the past 75 years, the vast majority of televisions have been built around the same technology: the cathode ray tube (CRT). In a CRT television, a gun fires a beam of electrons (negatively-charged particles) inside a large glass tube. The electrons excite phosphor atoms along the wide end of the tube (the screen), which causes the phosphor atoms to light up. The television image is produced by lighting up different areas of the phosphor coating with different colors at different intensities. Cathode ray tubes produce crisp, vibrant images, but they do have a serious drawback: They are bulky. In order to increase the screen width in a CRT set, you also have to increase the length of the tube (to give the scanning electron gun room to reach all parts of the screen). Consequently, any big-screen CRT television is going to weigh a ton and take up a sizable chunk of a room. A new alternative has popped up on store shelves: the plasma flat panel display. These televisions have wide screens, comparable to the largest CRT sets, but they are only about 6 inches (15 cm) thick. In this article, we'll see how these sets do so much in such a small space. If you've read How Television Works, then you understand the basic idea of a standard television or monitor. Based on the information in a video signal, the television lights up thousands of tiny dots (called pixels) with a high-energy beam of electrons. In most systems, there are three pixel colors -- red, green and blue -- which are evenly distributed on the screen. By combining these colors in different proportions, the television can produce the entire color spectrum. The basic idea of a plasma display is to illuminate tiny, colored fluorescent lights to form an image. Each pixel is made up of three fluorescent lights -- a red light, a green light and a blue light. Just like a CRT television, the plasma display varies the intensities of the different lights to produce a full range of colors. What is plasma? The central element in a fluorescent light is a plasma, a gas made up of free-flowing ions (electrically charged atoms) and electrons (negatively charged particles). Under normal conditions, a gas is mainly made up of uncharged particles. That is, the individual gas atoms include equal numbers of protons (positively charged particles in the atom's nucleus) and electrons. The negatively charged electrons perfectly balance the positively charged protons, so the atom has a net charge of zero. If you introduce many free electrons into the gas by establishing an electrical voltage across it, the situation changes very quickly. The free electrons collide with the atoms, knocking loose other electrons. With a missing electron, an atom loses its balance. It has a net positive charge, making it an ion. In a plasma with an electrical current running through it, negatively charged particles are rushing toward the positively charged area of the plasma, and positively charged particles are rushing toward the negatively charged area. ­In this mad rush, particles are constantly bumping into each other. These collisions excite the gas atoms in the plasma, causing them to release photons of energy. Xenon and neon atoms, the atoms used in plasma screens, release light photons when they are excited. Mostly, these atoms release ultraviolet light photons, which are invisible to the human eye. But ultraviolet photons can be used to excite visible light photons. Inside a Plasma Display The xenon and neon gas in a plasma television is contained in hundreds of thousands of tiny cells positioned between two plates of glass. Long electrodes are also sandwiched between the glass plates, on both sides of the cells. The address electrodes sit behind the cells, along the rear glass plate. The transparent display electrodes, which are surrounded by an insulating dielectric material and covered by a magnesium oxide protective layer, are mounted above the cell, along the front glass plate. Both sets of electrodes extend across the entire screen. The display electrodes are arranged in horizontal rows along the screen and the address electrodes are arranged in vertical columns. As you can see in the diagram below, the vertical and horizontal electrodes form a basic grid. To ionize the gas in a particular cell, the plasma display's computer charges the electrodes that intersect at that cell. It does this thousands of times in a small fraction of a second, charging each cell in turn. When the intersecting electrodes are charged (with a voltage difference between them), an electric current flows through the gas in the cell. As we saw in the last section, the current creates a rapid flow of charged particles, which stimulates the gas atoms to release ultraviolet photons. The released ultraviolet photons interact with phosphor material coated on the inside wall of the cell. Phosphors are substances that give off light when they are exposed to other light. When an ultraviolet photon hits a phosphor atom in the cell, one of the phosphor's electrons jumps to a higher energy level and the atom heats up. When the electron falls back to its normal level, it releases energy in the form of a visible light photon. The phosphors in a plasma display give off colored light when they are excited. Every pixel is made up of three separate subpixel cells, each with different colored phosphors. One subpixel has a red light phosphor, one subpixel has a green light phosphor and one subpixel has a blue light phosphor. These colors blend together to create the overall color of the pixel. By varying the pulses of current flowing through the different cells, the control system can increase or decrease the intensity of each subpixel color to create hundreds of different combinations of red, green and blue. In this way, the control system can produce colors across the entire spectrum. The main advantage of plasma display technology is that you can produce a very wide screen using extremely thin materials. And because each pixel is lit individually, the image is very bright and looks good from almost every angle. The image quality isn't quite up to the standards of the best cathode ray tube sets, but it certainly meets most people's expectations. The biggest drawback of this technology has been the price. However, falling prices and advances in technology mean that the plasma display may soon edge out the old CRT sets. Building a Digital Thermometer October 11, 2009 at 10:13 am Now that you understand a little bit about your Stamp and the LCD, we can add another component and create a digital thermometer. To create a thermometer, we will use a chip called the DS1620. This chip contains: * A temperature-sensing device * An analog-to-digital (A/D) converter for the temperature-sensing device * A shift register to read the data out of the A/D converter * A little EEPROM (electrically erasable programmable read-only memory) to remember settings The DS1620 has two modes: In one mode, it acts as a stand-alone thermostat chip, and in the other mode you hook it up to a computer and use it as a thermometer. The EEPROM remembers the current mode as well as the set temperatures for the thermostat. Hooking up the DS1620 to the Stamp is very easy. The DS1620 comes in an 8-pin chip. Supply +5 volts from the Stamp to pin 8 of the DS1620. Supply ground to pin 4 of the DS1620. You then use three I/O pins from the Stamp to drive three pins on the DS1620: * Pin 1 on the DS1620 is the data pin. You read and write data bits on this pin. * Pin 2 on the DS1620 is the clock pin. You clock data in and out of the shift register with this pin. * Pin 3 on the DS1620 is the reset/select pin. You set pin 3 high to select the chip and communicate with it. For this example code, it is assumed that: * The data pin goes to I/O pin 2 on the Stamp. * The clock pin goes to I/O pin 1 on the Stamp. * The reset/select pin goes to I/O pin 0 on the Stamp. The completed wiring looks like the picture. You can get a DS1620 either from Jameco (part number 146456) or Parallax (part number 27917) in an "application kit" that includes the chip, the capacitor, some good documentation and sample code. Or you can buy the chip on its own from Jameco (part number 114382). I would suggest getting the application kit the first time you try using the DS1620 because the documentation is very useful. You can assemble the DS1620 in the prototype area of the Stamp carrier board or on a separate breadboard. Once you have assembled it, hook your LCD display up to I/O pin 3 of the Stamp, and then load and run the following program: symbol RST = 0 ' select/reset line on 1620 symbol CLK = 1 ' clock line for shift registers on 1620 symbol DQ = 2 ' data line on 1620 symbol DQ_PIN = pin2 ' pin representation for DQ symbol LCD = 3 ' data line for LCD begin: low RST ' deselect the 1620 unless talking to it high CLK ' clock pin on 1620 should default high pause 1000 ' wait for the thermometer and LCD to boot setup: high RST ' select the 1620 b0 = $0C ' $0c is the 1620 command byte ' saying "Write Config" gosub shift_out ' send it to the 1620 b0 = %10 ' %10 is the 1620 command byte ' to set thermometer mode gosub shift_out ' send it to the 1620 low RST ' deselect the 1620 pause 50 ' delay 50ms for EEPROM start_convert: b0 = $EE ' $EE is the 1620 command byte ' to start conversions high RST ' select the 1620 gosub shift_out ' send it to the 1620 low RST ' deselect the 1620 ' This is the main loop ' - reads and displays temperature every second main_loop: high RST ' select the 1620 b0 = $AA ' $AA is the 1620 command byte ' for reading temperature gosub shift_out ' send it to the 1620 gosub shift_in ' read the temperature ' from the 1620 low RST ' deselect the DS1620. gosub display ' display the temp in degrees C pause 1000 ' wait a second goto main_loop ' The shift_out subroutine sends whatever is in ' the b0 byte to the 1620 shift_out: output DQ ' set the DQ pin to ' output mode for b2 = 1 to 8 low CLK ' prepare to clock the bit ' into 1620 DQ_PIN = bit0 ' Send the data bit high CLK ' latch data bit into 1620 b0 = b0/2 ' shift all bits right ' toward bit 0 next return ' The shift_in subroutine gets a 9-bit ' temperature from the 1620 shift_in: input DQ ' set the DQ pin to ' input mode w0 = 0 ' clear w0 for b5 = 1 to 9 w0 = w0/2 ' shift input right. low CLK ' ask 1620 for next bit bit8 = DQ_PIN ' read the bit high CLK ' toggle clock pin next return ' Displays the temperature in degrees C display: if bit8 = 0 then pos ' if bit8=1 ' then temp is negative b0 = b0 &/ b0 ' invert b0 by NANDing it ' with itself b0 = b0 + 1 pos: serout LCD, n2400, (254, 1) ' clear the LCD serout LCD, n2400, ("Temp = ") ' display "Temp=" ' on the display bit9 = bit0 ' save the half degree b0 = b0 / 2 ' convert to degrees if bit8 = 1 then neg ' see if temp is negative serout LCD, n2400, (#b0) ' display positive temp goto half neg: serout LCD, n2400, ("-", #b0)' display negative temp half: if bit9 = 0 then even serout LCD, n2400, (".5 C") ' display the half degree goto done even: serout LCD, n2400, (".0 C") ' display the half degree done: return If you run this program, you will find that it displays the centigrade temperature with an accuracy of one-half degree. The DS1620 measures temperatures in centigrade half-degrees. It returns the temperature in a 9-bit 2s-complement number with a range of -110 to 250 F (-55 to 125 C). You divide the number you receive by 2 to get the actual temperature. 2s-complement binary numbers are a convenient way to represent negative values. The following list shows the values for a 4-bit 2s-complement number: 0111 : 7 0110 : 6 0101 : 5 0100 : 4 0011 : 3 0010 : 2 0001 : 1 0000 : 0 1111 : -1 1110 : -2 1101 : -3 1100 : -4 1011 : -5 1010 : -6 1001 : -7 1000 : -8 ­ You can see that instead of the 4 bits representing values from 0 to 15, the 4 bits in a 2s-complement number represent the values -8 to 7. You can look at the left-most bit to determine if the number is negative or positive. If the number is negative, you can invert the bits and add 1 to get the positive representation of the number. Here's what goes on with the digital thermometer program shown here: 1. It uses the symbol keyword to set up several constants that make the program slightly easier to read (and also make it easy for you to move the chip to different I/O pins on the Stamp). 2. It sets the CLK and RST pins on the DS1620 to their expected values. 3. It writes a command byte to the EEPROM on the DS1620 to tell the chip to operate in "thermometer mode." Because the mode is stored in EEPROM, you only have to do it once, so you could technically take this section of the code out of the program after you run the program once (to save program space). 4. The program sends the command $EE ("$" means "hexadecimal number" -- $EE is 238 in decimal) to tell the thermometer to start up its conversion process. The program then enters a loop. Every second, it sends a command to the DS1620 telling the DS1620 to return the current temperature, and then it reads the 9-bit value that the DS1620 returns into the w0 variable. The Stamp sends and receives data 1 bit at a time by toggling the CLK line on the DS1620. Remember that the w0 (16-bit) variable overlays the b0/b1 (8-bit) variables, which overlay the bit0/bit1/.../bit15 (1-bit) variables, so when you insert a bit from the DS1620 into bit 8 and divide w0 by 2, what you are doing is shifting each bit to the right to store the 9-bit temperature from the DS1620 into w0. Once the temperature has been saved in w0, the display subroutine determines whether the number is positive or negative and displays it appropriately on the LCD as a centigrade temperature. The conversion from degrees C to degrees F is: dF = dC * 9/5 + 32 At this point, we have succeeded in creating an extremely expensive thermometer. What might you do with it? Here's one idea. Let's say you work for a drug company and you are shipping expensive drugs across the country that MUST remain at a certain temperature the entire way or the drugs will spoil. What you can do with a Stamp is create a data logging thermometer. Both Jameco (part number 143811) and Parallax (part number 27960) sell a device called the "RAM Pack module." It contains a low-power 8-kilobyte (or optionally 32-kilobyte) RAM chip with a serial interface. You could add this component (or something similar) to your Stamp and write code that saves temperature readings to the RAM every minute. You could then slip your Stamp into the drug shipment, and at the other end of the trip retrieve the Stamp. The RAM module would contain the temperature history of the entire trip and you would know whether or not the drugs ever thawed out. There are all kinds of neat, useful devices like this that you can build with a Stamp now that you know how microcontrollers work! Creating a Really Expensive Digital Clock using microcontroller October 11, 2009 at 10:13 am First, Playing with a BASIC Stamp If you would like to play with a BASIC Stamp, it's very easy to get started. What you need is a desktop computer and a BASIC Stamp starter kit. The starter kit includes the Stamp, a programming cable and an application that you run on your desktop computer to download BASIC programs into the Stamp. You can get a starter kit either from Parallax (the manufacturer) or from a supplier like Jameco. From Parallax, you can order the BASIC Stamp D Starter Kit (part number 27202), or from Jameco you can order part number 140089. You will receive the Stamp, a programming cable, software and instructions. The kit is $79 from both suppliers. Occasionally, Parallax runs a special called "We've Bagged the Basics" that also includes Scott Edward's Programming and Customizing the BASIC Stamp Computer. Hooking up the Stamp is easy. You connect it into the parallel port of your PC. Then you run a DOS application to edit your BASIC program and download it to the Stamp. Here is a screenshot of a typical editor (in this case, the one from Scott Edward's book). To run the program in this editor, you hit ALT-R. The editor application checks the BASIC program and then sends it down the wire to the EEPROM on the Stamp. The Stamp then executes the program. In this case, the program produces a square wave on I/O pin 3. If you hook up a logic probe or LED to pin 3, you will see the LED flash on and off twice per second (it changes state every 250 milliseconds because of the PAUSE commands). This program would run for several weeks off of a 9-volt battery. You could save power by shortening the time that the LED is on (perhaps it is on for 50 milliseconds and off for 450 milliseconds), and also by using the NAP instruction instead of PAUSE. Now, Creating a Really Expensive Digital Clock Spending $79 to flash an LED may seem extravagant to you. What you would probably like to do is create something useful with your BASIC stamp. By spending about $100 more you can create a really nice digital clock! This may seem extremely extravagant, until you realize that the parts are reusable in a variety of other projects that you may want to build later. Let's say that we would like to use the I/O pins on the BASIC Stamp to display numeric values. 7447s would work just as well with the BASIC Stamp. You could wire four of the I/O pins straight into a 7447 and easily display a number between 0 and 9. Since the BS-1 Stamp has eight I/O pins, it is easy to drive two 7447s directly like this. For a clock, we need a minimum of four digits. To drive four 7447s with eight I/O pins, we have to be slightly more creative. The diagram shows you one approach. In this diagram, the eight I/O lines from the Stamp enter from the left. This approach uses four lines that run to all four 7447s. Then the other four lines from the Stamp activate the 7447s in sequence ("E" on the chips means "Enable" -- on a 7447, that would be the blanking input on pin 5). To make this arrangement work, the BASIC program in the Stamp would output the first digit on the four data lines and activate the first 7447 by toggling its E pin with the first control line. Then it would send out the value for the second digit and activate the second 7447, sequencing through all four of the 7447s like this repeatedly. By wiring things slightly differently, you could actually do this with only one 7447. By using a 74154 demultiplexer chip and some drivers, you could drive up to 16 digits using this approach. This is, in fact, a standard way to control LED displays. For example, if you have an old LED calculator, turn it on and shake it while watching the display. You will actually be able to see that only one digit is ever illuminated at once. The approach is called multiplexing the display. While this approach works fine for clocks and calculators, it has two important problems: * LEDs consume a lot of power. * 7-segment LEDs can only display numeric values. An alternative approach is to use an LCD screen. As it turns out, LCDs are widely available and can be easily hooked to a Stamp. For example, the two-line by 16-character alphanumeric display shown below is available from both Jameco (part number 150990) and Parallax (part number 27910). A typical display is shown here, mounted on a breadboard for easier interfacing. This sort of LCD has several advantages: * The display can be driven by a single I/O pin. The display contains logic that lets a Stamp communicate with it serially, so only one I/O pin is needed. In addition, the SEROUT command in Stamp BASIC handles serial communication easily, so talking to the display is simple. * The LCD can display alphanumeric text: letters, numbers and even custom characters. * The LCD consumes very little power -- only 3 milliamps. The only problem is that one of these displays costs $59. Obviously, you would not embed one of these in a toaster oven. If you were designing a toaster oven, however, you would likely prototype with one of these displays and then create custom chips and software to drive much cheaper LCDs in the final product. To drive a display like this, you simply supply it with +5 volts and ground (the Stamp supplies both from the 9-volt battery) and then hook one of the I/O pins from the Stamp to the display's input line. The easiest way I have found to connect the Stamp's I/O pins to a device like an LCD is to use a wire-wrap tool (Jameco part number 34577) and 30-gauge wire wrap wire (Jameco part number 22541 is typical). That way, no soldering is involved and the connections are compact and reliable. The following BASIC program will cause a BASIC Stamp to behave like a clock and output the time on the LCD (assuming the LCD is connected to I/O pin 0 on the Stamp): pause 1000 'wait for LCD display to boot serout 0, n2400, (254, 1) 'clear the display serout 0, n2400, ("time:") 'Paint "time:" on the display 'preset before loading program b0 = 0 'seconds b1 = 27 'minutes b2 = 6 'hours again: b0 = b0 + 1 'increment seconds if b0 < 60 then minutes b0 = 0 'if seconds=60 b1 = b1 + 1 ' then increment minutes minutes: if b1 < 60 then hours b1 = 0 'if minutes=60 b2 = b2 + 1 ' then increment hours hours: if b2 < 13 then show b2 = 1 'if hours=13 reset to 1 show: serout 0, n2400, (254, 135) 'position cursor on display, 'then display time serout 0, n2400, (#b2, ":", #b1, ":", #b0, " ") pause 950 'pause 950 milliseconds goto again 'repeat In this program, the SEROUT commands send data to the LCD. The sequence (254, 1) clears the LCD (254 is the escape character and 1 is the command to clear the screen). The sequence (254, 135) positions the cursor. The other two SEROUT commands simply send text strings to the display. This approach will create a reasonably accurate clock. By tweaking the PAUSE statement you can get the accuracy to within a few seconds a day. Obviously, in a real clock you would like to wire up a push-button or two to make setting it easier -- in this program, you preset the time before you download the program to the Stamp. While this approach is simple and works, it is not incredibly accurate. If you want better accuracy, one good approach would be to wire a real-time clock chip up to your Stamp. Then, every second or so, you can read the time from the chip and display it. A real-time clock chip uses a quartz crystal to give it excellent accuracy. Clock chips also usually contain date information and handle leap year correction automatically. One easy way to interface a real-time clock to a stamp is to use a component called the Pocket Watch B. The Pocket Watch B is available from both Jameco (part number 145630) and Parallax (part number 27962). This part is about as big as a quarter and contains the clock chip, crystal and a serial interface so that only one I/O pin is necessary to communicate with it. This component costs about $30 -- again, not something you want to embed in a toaster oven, but easy to play with when constructing prototypes. Microcontrollers October 11, 2009 at 10:11 am Microcontrollers are hidden inside a surprising number of products these days. If your microwave oven has an LED or LCD screen and a keypad, it contains a microcontroller. All modern automobiles contain at least one microcontroller, and can have as many as six or seven: The engine is controlled by a microcontroller, as are the anti-lock brakes, the cruise control and so on. Any device that has a remote control almost certainly contains a microcontroller: TVs, VCRs and high-end stereo systems all fall into this category. Nice SLR and digital cameras, cell phones, camcorders, answering machines, laser printers, telephones (the ones with caller ID, 20-number memory, etc.), pagers, and feature-laden refrigerators, dishwashers, washers and dryers (the ones with displays and keypads)... You get the idea. Basically, any product or device that interacts with its user has a microcontroller buried inside. We will look at microcontrollers so that you can understand what they are and how they work. Then we will go one step further and discuss how you can start working with microcontrollers yourself -- we will create a digital clock with a microcontroller! We will also build a digital thermometer. In the process, you will learn an awful lot about how microcontrollers are used in commercial products. What is a Microcontroller? A microcontroller is a computer. All computers -- whether we are talking about a personal desktop computer or a large mainframe computer or a microcontroller -- have several things in common: * All computers have a CPU (central processing unit) that executes programs. If you are sitting at a desktop computer right now reading this article, the CPU in that machine is executing a program that implements the Web browser that is displaying this page. * The CPU loads the program from somewhere. On your desktop machine, the browser program is loaded from the hard disk. * The computer has some RAM (random-access memory) where it can store "variables." * And the computer has some input and output devices so it can talk to people. On your desktop machine, the keyboard and mouse are input devices and the monitor and printer are output devices. A hard disk is an I/O device -- it handles both input and output. The desktop computer you are using is a "general purpose computer" that can run any of thousands of programs. Microcontrollers are "special purpose computers." Microcontrollers do one thing well. There are a number of other common characteristics that define microcontrollers. If a computer matches a majority of these characteristics, then you can call it a "microcontroller": * Microcontrollers are "embedded" inside some other device (often a consumer product) so that they can control the features or actions of the product. Another name for a microcontroller, therefore, is "embedded controller." * Microcontrollers are dedicated to one task and run one specific program. The program is stored in ROM (read-only memory) and generally does not change. * Microcontrollers are often low-power devices. A desktop computer is almost always plugged into a wall socket and might consume 50 watts of electricity. A battery-operated microcontroller might consume 50 milliwatts. * A microcontroller has a dedicated input device and often (but not always) has a small LED or LCD display for output. A microcontroller also takes input from the device it is controlling and controls the device by sending signals to different components in the device. For example, the microcontroller inside a TV takes input from the remote control and displays output on the TV screen. The controller controls the channel selector, the speaker system and certain adjustments on the picture tube electronics such as tint and brightness. The engine controller in a car takes input from sensors such as the oxygen and knock sensors and controls things like fuel mix and spark plug timing. A microwave oven controller takes input from a keypad, displays output on an LCD display and controls a relay that turns the microwave generator on and off. * A microcontroller is often small and low cost. The components are chosen to minimize size and to be as inexpensive as possible. * A microcontroller is often, but not always, ruggedized in some way. The microcontroller controlling a car's engine, for example, has to work in temperature extremes that a normal computer generally cannot handle. A car's microcontroller in Alaska has to work fine in -30 degree F (-34 C) weather, while the same microcontroller in Nevada might be operating at 120 degrees F (49 C). When you add the heat naturally generated by the engine, the temperature can go as high as 150 or 180 degrees F (65-80 C) in the engine compartment. On the other hand, a microcontroller embedded inside a VCR hasn't been ruggedized at all. The actual processor used to implement a microcontroller can vary widely. For example, the cell phone shown on Inside a Digital Cell Phone contains a Z-80 processor. The Z-80 is an 8-bit microprocessor developed in the 1970s and originally used in home computers of the time. The Garmin GPS shown in How GPS Receivers Work contains a low-power version of the Intel 80386, I am told. The 80386 was originally used in desktop computers. In many products, such as microwave ovens, the demand on the CPU is fairly low and price is an important consideration. In these cases, manufacturers turn to dedicated microcontroller chips -- chips that were originally designed to be low-cost, small, low-power, embedded CPUs. The Motorola 6811 and Intel 8051 are both good examples of such chips. There is also a line of popular controllers called "PIC microcontrollers" created by a company called Microchip. By today's standards, these CPUs are incredibly minimalistic; but they are extremely inexpensive when purchased in large quantities and can often meet the needs of a device's designer with just one chip. A typical low-end microcontroller chip might have 1,000 bytes of ROM and 20 bytes of RAM on the chip, along with eight I/0 pins. In large quantities, the cost of these chips can sometimes be just pennies. You certainly are never going to run Microsoft Word on such a chip -- Microsoft Word requires perhaps 30 megabytes of RAM and a processor that can run millions of instructions per second. But then, you don't need Microsoft Word to control a microwave oven, either. With a microcontroller, you have one specific task you are trying to accomplish, and low-cost, low-power performance is what is important. Using Microcontrollers In How Electronic Gates Work, you learned about 7400-series TTL devices, as well as where to buy them and how to assemble them. What you found is that it can often take many gates to implement simple devices. For example, in the digital clock post, the clock we designed might contain 15 or 20 chips. One of the big advantages of a microcontroller is that software -- a small program you write and execute on the controller -- can take the place of many gates. In this article, therefore, we will use a microcontroller to create a digital clock. This is going to be a rather expensive digital clock (almost $200!), but in the process you will accumulate everything you need to play with microcontrollers for years to come. Even if you don't actually create this digital clock, you will learn a great deal by reading about it. The microcontroller we will use here is a special-purpose device designed to make life as simple as possible. The device is called a "BASIC Stamp" and is created by a company called Parallax. A BASIC Stamp is a PIC microcontroller that has been customized to understand the BASIC programming language. The use of the BASIC language makes it extremely easy to create software for the controller. The microcontroller chip can be purchased on a small carrier board that accepts a 9-volt battery, and you can program it by plugging it into one of the ports on your desktop computer. It is unlikely that any manufacturer would use a BASIC Stamp in an actual production device -- Stamps are expensive and slow (relatively speaking). However, it is quite common to use Stamps for prototyping or for one-off demo products because they are so incredibly easy to set up and use. They are called "Stamps," by the way, because they are about as big as a postage stamp. Parallax makes two versions of the BASIC Stamp: the BS-1 and the BS-2. Here are some of the differences between the two models: Spec BS-1 BS-2 RAM 14 bytes 26 bytes EEPROM 256 bytes 2 kilobytes Max program length 75 instructions 600 instructions Execution speed 2,000 lines/sec 4,000 lines/sec I/O pins 8 16 The specific BASIC Stamp we will be using in the post is called the "BASIC Stamp Revision D" The BASIC Stamp Revision D is a BS-1 mounted on carrier board with a 9-volt battery holder, a power regulator, a connection for a programming cable, header pins for the I/O lines and a small prototyping area. You could buy a BS-1 chip and wire the other components in on a breadboard. The Revision D simply makes life easier. You can see from the previous table that you aren't going to be doing anything exotic with a BASIC stamp. The 75-line limit (the 256 bytes of EEPROM can hold a BASIC program about 75 lines long) for the BS-1 is fairly constraining. However, you can create some pretty neat stuff, and the fact that the Stamp is so small and battery operated means that it can go almost anywhere. Programming the BASIC Stamp You program a BASIC Stamp using the BASIC programming language. If you already know BASIC, then you will find that the BASIC used in a Stamp is straightforward but a little stripped-down. If you don't know BASIC, but you do know another language like C, Pascal or Java, then picking up BASIC will be trivial. If you have never programmed before, you probably want to go learn programming on a desktop machine first. Here is a quick rundown on the instructions available in Stamp BASIC. Standard BASIC instructions: * for...next - normal looping statement * gosub - go to a subroutine * goto - goto a label in the program (e.g. - "label:") * if...then - normal if/then decision * let - assignment (optional) * return - return from a subroutine * end - end the program and sleep Instructions having to do with I/O pins: * button - read a button on an input pin, with debounce and auto-repeat * high - set an I/O pin high * input - set the direction of an I/O pin to input * low - set an I/O pin low * output - set the direction of an I/O pin to output * pot - read a potentiometer on an I/O pin * pulsin - read the duration of a pulse coming in on an input pin * pulsout - send a pulse of a specific duration out on an output pin * pwm - perform pulse width modulation on an output pin * reverse - reverse the direction of an I/O pin * serin - read serial data on an input pin * serout - write serial data on an output pin * sound - send a sound of a specific frequency to an output pin * toggle - toggle the bit on an output pin Instructions specific to the BASIC Stamp: * branch - read a branching table * debug - send a debugging string to the console on the desktop computer * eeprom - download a program to EEPROM * lookdown - return the index of a value in a list * lookup - array lookup using an index * nap - sleep for a short time * pause - delay for the specified time * random - pick a random number * read - read a value from EEPROM * sleep - power down for the specified time * write - write data to EEPROM Operations: * + - addition * - - subtraction * * - multiplication (low-word) * ** - multiplication (high-word) * / - division * // - mod * max - return maximum of 2 values * min - return minimum of 2 values * & - AND * | - OR * ^ - XOR * &/ - NAND * |/ - NOR * ^/ - XNOR If statement logic: * = * <> * < * <= * > * >= * AND * OR Variables All variables in the BS-1 have pre-defined names (which you can substitute with names of your own). Remember that there are only 14 bytes of RAM available, so variables are precious. Here are the standard names: * w0, w1, w2...w6 - 16-bit word variables * b0, b1, b2...b13 - 8-bit byte variables * bit0, bit1, bit2...bit15 - 1-bit bit variables Because there are only 14 bytes of memory, w0 and b0/b1 are the same locations in RAM, and w1 and b2/b3 are the same, and so on. Also, bit0 through bit15 reside in w0 (and therefore b0/b1 as well). I/O pins You can see that 14 of the instructions in the BS-1 have to do with the I/O pins. The reason for this emphasis is the fact that the I/O pins are the only way for the BASIC Stamp to talk to the world. There are eight pins on the BS-1 (numbered 0 to 7) and 16 pins on the BS-2 (numbered 0 to 15). The pins are bi-directional, meaning that you can read input values on them or send output values to them. The easiest way to send a value to a pin is to use the HIGH or LOW functions. The statement high 3 sends a 1 (+5 volts) out on pin 3. LOW sends a 0 (Ground). Pin 3 was chosen arbitrarily here -- you can send bits out on any pin from 0 to 7. There are a number of interesting I/O pin instructions. For example, POT reads the setting on a potentiometer (variable resistor) if you wire it up with a capacitor as the POT instruction expects. The PWM instruction sends out pulse-width modulated signals. Instructions like these can make it a lot easier to attach controls and motors to the Stamp. See the documentation for the language for details. Also, a book like Scott Edward's Programming and Customizing the BASIC Stamp Computer can be extremely helpful because of the example projects it contains. Diodes and Transistors October 11, 2009 at 10:10 am A device that blocks current in one direction while letting current flow in another direction is called a diode. Diodes can be used in a number of ways. For example, a device that uses batteries often contains a diode that protects the device if you insert the batteries backward. The diode simply blocks any current from leaving the battery if it is reversed -- this protects the sensitive electronics in the device. A semiconductor diode's behavior is not perfect, as shown in this graph. When reverse-biased, an ideal diode would block all current. A real diode lets perhaps 10 microamps through -- not a lot, but still not perfect. And if you apply enough reverse voltage (V), the junction breaks down and lets current through. Usually, the breakdown voltage is a lot more voltage than the circuit will ever see, so it is irrelevant. When forward-biased, there is a small amount of voltage necessary to get the diode going. In silicon, this voltage is about 0.7 volts. This voltage is needed to start the hole-electron combination process at the junction. Another monumental technology that's related to the diode is the transistor. Transistors and diodes have a lot in common. Transistors A transistor is created by using three layers rather than the two layers used in a diode. You can create either an NPN or a PNP sandwich. A transistor can act as a switch or an amplifier. A transistor looks like two diodes back-to-back. You'd imagine that no current could flow through a transistor because back-to-back diodes would block current both ways. And this is true. However, when you apply a small current to the center layer of the sandwich, a much larger current can flow through the sandwich as a whole. This gives a transistor its switching behavior. A small current can turn a larger current on and off. A silicon chip is a piece of silicon that can hold thousands of transistors. With transistors acting as switches, you can create Boolean gates, and with Boolean gates you can create microprocessor chips. The natural progression from silicon to doped silicon to transistors to chips is what has made microprocessors and other electronic devices so inexpensive and ubiquitous in today's society. The fundamental principles are surprisingly simple. The miracle is the constant refinement of those principles to the point where, today, tens of millions of transistors can be inexpensively formed onto a single chip. Semiconductors October 11, 2009 at 10:09 am Semiconductors have had a monumental impact on our society. You find semiconductors at the heart of microprocessor chips as well as transistors. Anything that's computerized or uses radio waves depends on semiconductors. Today, most semiconductor chips and transistors are created with silicon. You may have heard expressions like "Silicon Valley" and the "silicon economy," and that's why -- silicon is the heart of any electronic device. A diode is the simplest possible semiconductor device, and is therefore an excellent beginning point if you want to understand how semiconductors work. In this article, you'll learn what a semiconductor is, how doping works and how a diode can be created using semiconductors. But first, let's take a close look at silicon. Silicon is a very common element -- for example, it is the main element in sand and quartz. If you look "silicon" up in the periodic table, you will find that it sits next to aluminum, below carbon and above germanium. Carbon, silicon and germanium (germanium, like silicon, is also a semiconductor) have a unique property in their electron structure -- each has four electrons in its outer orbital. This allows them to form nice crystals. The four electrons form perfect covalent bonds with four neighboring atoms, creating a lattice. In carbon, we know the crystalline form as diamond. In silicon, the crystalline form is a silvery, metallic-looking substance. Metals tend to be good conductors of electricity because they usually have "free electrons" that can move easily between atoms, and electricity involves the flow of electrons. While silicon crystals look metallic, they are not, in fact, metals. All of the outer electrons in a silicon crystal are involved in perfect covalent bonds, so they can't move around. A pure silicon crystal is nearly an insulator -- very little electricity will flow through it. But you can change all this through a process called doping. Doping Silicon You can change the behavior of silicon and turn it into a conductor by doping it. In doping, you mix a small amount of an impurity into the silicon crystal. There are two types of impurities: * N-type - In N-type doping, phosphorus or arsenic is added to the silicon in small quantities. Phosphorus and arsenic each have five outer electrons, so they're out of place when they get into the silicon lattice. The fifth electron has nothing to bond to, so it's free to move around. It takes only a very small quantity of the impurity to create enough free electrons to allow an electric current to flow through the silicon. N-type silicon is a good conductor. Electrons have a negative charge, hence the name N-type. * P-type - In P-type doping, boron or gallium is the dopant. Boron and gallium each have only three outer electrons. When mixed into the silicon lattice, they form "holes" in the lattice where a silicon electron has nothing to bond to. The absence of an electron creates the effect of a positive charge, hence the name P-type. Holes can conduct current. A hole happily accepts an electron from a neighbor, moving the hole over a space. P-type silicon is a good conductor. A minute amount of either N-type or P-type doping turns a silicon crystal from a good insulator into a viable (but not great) conductor -- hence the name "semiconductor." N-type and P-type silicon are not that amazing by themselves; but when you put them together, you get some very interesting behavior at the junction. That's what happens in a diode. A diode is the simplest possible semiconductor device. A diode allows current to flow in one direction but not the other. You may have seen turnstiles at a stadium or a subway station that let people go through in only one direction. A diode is a one-way turnstile for electrons. When you put N-type and P-type silicon together as shown in this diagram, you get a very interesting phenomenon that gives a diode its unique properties. Even though N-type silicon by itself is a conductor, and P-type silicon by itself is also a conductor, the combination shown in the diagram does not conduct any electricity. The negative electrons in the N-type silicon get attracted to the positive terminal of the battery. The positive holes in the P-type silicon get attracted to the negative terminal of the battery. No current flows across the junction because the holes and the electrons are each moving in the wrong direction. If you flip the battery around, the diode conducts electricity just fine. The free electrons in the N-type silicon are repelled by the negative terminal of the battery. The holes in the P-type silicon are repelled by the positive terminal. At the junction between the N-type and P-type silicon, holes and free electrons meet. The electrons fill the holes. Those holes and free electrons cease to exist, and new holes and electrons spring up to take their place. The effect is that current flows through the junction. UMPC Battery Life October 11, 2009 at 10:08 am Ultra-Mobile PC (part 2) One of the biggest issues for any portable device is how it uses power and whether its batteries can run an entire eight-hour day without having to be recharged. While the UMPC is still too new to determine whether this will be the case, there are several indications from Microsoft staff and from analysts that it will be a very power-hungry device. Part of the problem is that 7-inch screen, which consumes a great deal of power. Microsoft is aiming for at least a two-hour battery profile, but early testers say that even that amount of time will be hard to deliver. This means that batteries won't be able to last as long as watching your average movie on the UMPC. Michael Gartenberg of Jupiter Research wrote in his blog, "What is missing? Battery life. Right now these machines really need to be sold with a higher capacity battery if you're going to use one as a life style device going through the day." There are numerous notebooks available today that offer three or more hours of battery life, including ones from Sony, Fujitsu and Motion Computing. Of course, these are all larger form factors and thus able to have bigger batteries included to last longer. To counteract this issue, Microsoft has tried to finesse things by offering more advanced power management on the UMPC. Like many of today's more advanced multimedia laptops, the unit will have a special quick boot sequence that will bring up an embedded OS to run movies or play music files. Dustin Hubbard at Microsoft writes in his blog, "The Samsung unit actually has 2 boot modes on a 3 way power switch - On, Off and AVS Multimedia (that's their name for this mode). AVS Multimedia can do near instant on by booting into what appears to be XP Embedded (as far as I can tell that is what they are doing) and allows you to play movies, music and photos without requiring you to boot into full XP. That gives you 2 advantages; presumably better battery life by not having so many services running in the background and fast cold boot startup for media only consumption." Touch Pack Enhancements Microsoft has developed a special series of operating system enhancements to the tablet OS to take advantage of the UMPC platform. Called the "Touch Pack," these enhancements will optimize the touch screen experience. It has five applications: a program launcher, a series of touch improvements to the normal Windows UI, a Brilliant Black skin for Media player, a Sudoku game, and Dial Keys, a thumb-based on-screen keyboard for inputting text. "Currently the Touch Pack is available only to UMPC qualified computers and only as an OEM pre-install," says Hubbard. "The Touch Pack was designed specifically for small form factor PCs." Microsoft's Mitchell says, "Microsoft Touch Pack for Windows XP software optimizes the touch screen user interface for UMPCs to simplify navigation and ease-of-use while on the go. The Touch Pack's customizable Program Launcher organizes software programs into categories, and uses large buttons and icons to make it easy to find and open your favorite applications." Most of the marketing materials that show screen shots of the UMPC feature views of this application. There are several components to the Touch Pack. The first one is "Touch Improvements." This utility makes about 10 different settings changes to Windows such as widening the scroll bars and enlarging the minimize and maximize buttons, shows folders in thumbnail view. Next is a new skin for Windows Media Player called "Brilliant Black." This skin fills the screen on the devices with large buttons to navigate the media controls such as play, stop and volume. The third Touch Pack program is "DialKeys." This program, built by Fortune Fountain Ltd., is a way to input text with your thumbs. Dial Keys makes it easy to enter URLs, e-mail addresses, et cetera. "DialKeys basically takes a standard QWERTY keyboard layout and splits it in two halves. It's a little hard to describe the layout but there are lots of screen shots of DialKeys to show what it looks like. The basic idea is that you hold the device in two hands and use your thumbs on the screen to type in text. It takes a little getting used to, but people are always amazed once they use it a day or two how good they get at typing with it," says Hubbard on his blog. The final product in the Touch Pack is a Sudoku game. The version is optimized for touch and the pen. Manufacturing and Cost UMPCs from Samsung, Asus, and Founder are based on Intel microprocessors. PaceBlade Japan announced a UMPC, known as the SmartCaddie, that uses a VIA Technology chip. Samsung's Q1 went on sale in the second quarter of 2006 with a manufacturer's suggested retail price of $1,099. Another UMPC, manufactured by AMtek and available the United States as the TabletKiosk eo v7110, retails for $899. Asus' and Founder's UMPC should be available later this year. One vendor that hasn't announced any UMPC yet is Motion Computing, although the company sells a variety of tablet PCs in various shapes and sizes. "We see it as validation and reinforcement of where we were headed with tablet PCs," says Bert Haskell of Motion Computing. "We were drawn into the ultra-mobile tablets by our customers who wanted a higher level of mobility. It is nice to see that Microsoft is creating the same type of vision for a consumer-oriented product." Motion sells its tablets for the enterprise, and through the reseller channel, largely aimed at equipping sales forces and hospital staffs. "We have a significantly different focus in that we are looking at high-powered enterprise computing," says Haskell. Motion sells their tablets with higher-end components, such as with Pentium M CPUs and 60 GB hard disks with 1GB of RAM. " We are set up to understand and service the needs of the enterprise customers. We don't currently target consumer markets. If and when we decide to make that transition, it would be a pretty significant change for us," he said. Microsoft has promised that once Vista ships that the UMPC will be able to run some version of Vista as well, but since the new OS isn't yet finished it is hard to make any definitive claims in this area. "The Vista requirements aren't out yet, but realistically if the units have the hardware specifications that Vista requires they should be able to run it," says Microsoft's Hubbard. Just because the UMPC runs the tablet version of XP doesn't mean that every tablet-based application is worth running on it, however. "To be clear though not all tablet-enabled apps will make sense on a UMPC and not all UMPC apps will make sense on a traditional tablet," says Hubbard. "The small form factor and touch interaction of UMPC means that to have a really great user experience you need to design your UI to really take advantage of those assets." So chances are if UMPCs do take off, we will see differentiated applications over time that take advantage of its touch-screen features and enhancements that Microsoft is building into the units. UMPCs overall are expected will cost less than most tablets and more than most PDAs. It depends on what configurations the various vendors will initially offer and how they will be priced in local markets. Price is definitely an issue that has gotten some analysts going about the new units. "To me, one of the most important things about this, is price," stated Bob O'Donnell, program vice president for clients and displays at IDC. "If it's under $500, it's a fancy gadget. People spend that much on iPods. So there's this sense that, at a low price point, it could be very interesting and very appealing. Think about all the free WiFi networks that are out there now that you could use this thing with, and it gives you a full browsing experience as opposed to trying to browse on a two-inch cell phone, which is a horrendously useless experience. And yet people are getting more and more used to having information access almost anywhere they are, at almost any time." Scott Fulton of TGDaily.com, sums things up the best about UMPC's shortcomings: "But what we have instead is something that's larger than the average pocket, that can't dial out, that doesn't have a discrete way to connect to the outside world, is somewhat expensive, and perhaps most unanticipated of all, is power-hungry." So what will happen with the UMPC? Only time will tell. If manufacturers can get several hours of battery life, if the costs can drop way below $1000, if the touch experience works out for many new users, and if the right distributors pick up the products, this could be a winning product for Microsoft and its OEMs. Hitting all of these targets won't be easy, to be sure. But there is plenty of interest in UMPC and the size of the devices is very appealing. Ultra-Mobile PC (part 1) October 11, 2009 at 10:06 am It isn't often that Microsoft announces a completely new concept in computing, but at CeBIT 2006 in Hanover, Germany, the software giant finally unveiled details about its Origami Project to a worldwide audience. Microsoft created the Origami Project to develop (with various hardware and software partners) a new type of computer that falls in-between the size of a typical PDA and tablet PC, uses a standard Windows operating system and costs less than $1000: the Ultra-mobile PC, or UMPC. The Microsoft team originally used "Origami" as a code name, and they liked it so much that they kept it for the project's public community Web site. One of the program's managers was interested in Japanese culture and liked the name, which refers to the art of intricate paper folded sculptures. Clearly, there is a need for a smaller form factor than the traditional notebook PC. PDAs don't run standard Windows OS, and many tablets are too heavy to carry around all the time. Gartner, an IT research Web site, posits that the UMPC space should have the following advantages: * An eight-hour battery life. * A sub-$400 price. * Low-cost, compelling content bundles from partners like Intel and Microsoft. * A better Microsoft shell/interface running on top of Vista. * Text entry options beyond thumb-typing. * Dock-and-go synchronization, requiring minimal user interaction. * Sustained market momentum from Microsoft and Intel. These are all worthy goals, but the initial UMPC units won't deliver on all of these points at first. In this post, we'll show you what Microsoft has planned for the UMPC and what is still to come. We'll also talk about how these new computers will work and how they differ from tablets and PDAs. Ultra-mobile PC Software The UMPC is unique in that it runs regular Windows OS -- it currently runs XP Tablet edition and will run Vista in the future. While there are many PDAs and PDA/phone combinations that run Windows Mobile (such as the Palm Treo 700w) it isn't the same as running the stock XP OS loaded onto millions of desktop and laptop computers. Windows Mobile requires new versions of applications to be compatible with that OS, and the applications have to take advantage of the smaller screens on these devices. The goal of UMPC is to run off-the-shelf Windows applications, with no medications whatsoever other than supporting the tablet/touch screen features. The UMPCs that Microsoft announced are small devices -- they weigh less than two pounds and have seven-inch video screens. This puts it in a new market segment not currently served by any particular manufacturer. It is smaller than the smallest tablet PCs that are currently available from Motion and Fujitsu, and lighter than the Aopen MiniPC (a desktop model that doesn't include any screen at all). It is also bigger than the OQO PC. The other distinction is that the UMPC will be lessexpensive than the typical tablet. "Origami isn't an iPod killer per se, it's rather a new class of device that will compete with other devices that cost about the same," says Michael Gartenberg, an analyst at Jupiter Research, using the original code name for the UMPC. "That means portable media players, game machines, GPS units and the like will face some new challenges. Much like there were PCs with TV tuners long before MCE, the power of MCE was really the 10-foot UI. The power of Origami is really in the 10" UI." Bill Mitchell, corporate vice president of Microsoft's Windows Mobile Platforms Division said, "While the first generation of UMPCs will run Windows XP Tablet PC Edition 2005, future models will run on Windows Vista." Ultra-mobile PC Hardware This isn't the first time that Microsoft has tried to promote touch-screen tablets: Windows Tablet PCs have been around for nearly a decade, and XP Tablet edition is on its second iteration with all sorts of usability improvements. But the UMPC is another step in this evolution. In one report, Bill Mitchell said, "The touch-enhanced display can be used as an on-screen QWERTY keyboard [using Dial Keys] to navigate, or users can employ a stylus to input handwritten information. They can also input content with a traditional keyboard, linked either by USB port or wireless Bluetooth connectivity." Not all implementations of all UMPCs will have Bluetooth ports, but the initial crop of vendors have promised this, along with support for various USB and BT keyboards. This is very similar to the tablet PCs that are currently on the market: some come with keyboards and all offer support for either pen or keyboard input devices. Other input ports are planned for the devices, including: * Wired Ethernet and WiFi networking connectors. * Compact Flash card slots. * USB v 2.0 ports. * An external VGA monitor port. * Various buttons and connectors for audio operations. * Support for stereo microphones with built-in noise reduction and echo cancellation. * A remote control for the Media Center PC application. There will be units with a variety of processors, including the Intel Celeron M, Intel Pentium M and VIA C7-M. No AMD chipsets are in any of the announced plans yet. Microsoft's goal was to use off-the-shelf displays that are in common consumer electronics devices to keep the costs down. They settled on seven-inch VGA displays that had 800 x 480 native resolution and can handle 800 x 600 with some loss of quality. "The form factor was based around a 7-inch display panel, a size that is currently a standard size in the electronics industry due to broad adoption of that size display in the portable DVD player and automotive markets," said Microsoft's Otto Berkes in a newspaper interview. "Why use some new custom size when a potentially good one already exists?" These plans for the UMPC differ from the existing Motion Computing tablets. The Motion displays use high-contrast, non-glare, active digitizers, meaning that the pen sold with the tablet is the only way to enter information. The UMPC displays are general touchscreens that can work with a finger or any other object for input. "We designed our 8.4-inch display to meet the needs of legacy enterprise applications, because many of these applications are designed for SVGA (800 x 600) resolution," said Bert Haskell, a product manager for Motion Computing. The UMPC displays are designed for showing widescreen movies. Which is better to use for a cable modem, a USB connection or an Ethernet card? October 11, 2009 at 10:05 am USB port has a maximum data rate of 12 megabits per second (Mbps). However, of that available bandwidth, an individual USB device can use only up to 6 Mbps. And if you have several devices attached to the USB ports and they pump lots of data, this competition may further lower the data rate. An Ethernet card, on the other hand, connects directly to the computer's bus. Ethernet cards come in two flavors: one that accepts 10 Mbps, and another that accepts 100 Mbps. If you are on a cable modem late at night with no one else sharing the line (see How Cable Modems Work for a discussion on sharing), the cable modem can run at data rates faster than 10 Mbps. In normal circumstances, however, a few megabits per second is far more likely. Taking this into account, you could install a 100-Mbps Ethernet card if you want the best possible peak performance. Also, an Ethernet card is likely to be more consistent, since it is dedicated to network traffic (as opposed to a USB connection, which may handle traffic from a number of devices). One difference is the ease of installation. To install an Ethernet card, you have to open the computer casing, while the USB option takes 5 seconds to plug it in. How do I add a USB device to my computer if I am out of ports? October 11, 2009 at 10:05 am Just about every peripheral made now comes in a USB version. Here's a list of some of the USB devices that you can buy today: * Printers * Scanners * Mice * Joysticks * Flight yokes * Digital cameras * Webcams * Scientific data acquisition devices * Modems * Speakers * Telephones * Video phones * Storage devices like Zip drives * Network connections Most computers that you buy today come with only one or two USB sockets. With so many USB devices on the market today, you easily run out of sockets very quickly. For example, on the computer that I am typing on right now, I have a USB printer, a USB scanner, a USB Webcam and a USB network connection. My computer has only one USB connector on it, so the obvious question is, "How do you hook up all the devices?" The easy solution to the problem is to buy an inexpensive USB hub. The USB standard supports up to 127 devices, and USB hubs are a part of the standard. A hub typically has four new ports, but may have many more. You plug the hub into your computer, and then plug your devices (or other hubs) into the hub. By chaining hubs together, you can build up dozens of available USB ports on a single computer. Hubs can be powered or unpowered. The USB standard allows for devices to draw their power from their USB connection (all USB cables contain two wires -- for +5 volts and ground). A high-power device like a printer or scanner will have its own power supply, but low-power devices like mice and digital cameras get their power from the bus. The power (up to 500 milliamps at 5 volts) comes from the computer. If you have lots of self-powered devices (like printers and scanners), then your hub does not need to be powered -- none of the devices connecting to the hub need additional power, so the computer can handle it. If you have lots of unpowered devices like mice and cameras, you probably need a powered hub. The hub has its own transformer, and it supplies power to the devices that connect to the hub so the devices do not overload the computer's power supply. The Universal Serial Bus can easily handle both a scanner and a printer, even if you are scanning and printing at the same time. The original USB supports up to 12 megabits per second, and USB 2.0 supports up to 480 megabits per second -- considering that most devices consume only 6 megabits per second, you can definitely run more than one device at a time. Why You Need a Video Submission Service? October 11, 2009 at 10:02 am Have you ever think how to submit videos online? Do you need to put videos on a website? Why is there so much video today online? There was a recent headline in "Money" magazine that asked "How Online Videos Can Make You Rich" that referred to servers and bandwidth, but the fact of the matter remains that there is a lot more video online than ever before and the numbers appear to be rising. People tend to like video better than content online. They would rather watch a video than read content. This should come as no surprise to anyone as most people today would rather watch television than read a book. It should also come as no surprise to anyone that video marketing is so hot. By incorporating SEO into video marketing such as the Meta tags and titles, video marketing has a chance to do what other ads cannot - and that is get discovered by the search engines. And because the search engines love video, video ads tend to rank higher in the search engines than regular content. But you have to make sure that your video is search engine optimized. You cannot just submit it and hope for the best. Chances are that a non SEO video will get buried in the search engines, losing its full potential. When you get a video that is fully optimized and is submitted to a site like You Tube for viewing, you have the chance of millions of people viewing the video. Because it will rank higher in the search engines than regular content as well as a non SEO video, you have an opportunity to pull potential customers to your video from the search engines. After viewing your video, the same people are likely to come to your site and hopefully, buy your product. In order to be successful at creating a video, you have to have the right tools as well as knowledge. You will normally pay about $2,500 for a video to be created for you in a studio. This amount depends upon the length of the video as well as the content. Unless you are familiar with compression and formatting tools, chances are that you will most likely pay someone to create the video for you. But creating the video is not enough. You have to then submit it to the right sites. Not just YouTube, but the other sites online that are viewed frequently and will accept your video. There are at least 50 of them that will take your SEO video. The submission may take a lot of time on your part, but is a necessary step in marketing your video. Once that step has been completed and your SEO video has been submitted, you then have to market your video online. This entails submitting the video to the search engines, posting in blogs, forums and book marking the blogs on social networks. This can be time consuming, but is a necessary step towards getting your video to come to life online. If you do not have the time to market your video, you can get a video submission service to help you with this project. Finally, video submission is a great one that lets you to submit your video easily on any website and will not take a long time. Online Video Websites October 11, 2009 at 10:01 am There are many video websites which full of many video and allow any one submit their video or favorite shoots such as YouTube and Metacafe. Are an individual who loves getting your entertainment online? If so, there is a good chance that you know what online video sites are. In fact, there is also a good chance that you have visited, at least, one before. If you have, what did you think of the videos that you saw? If you liked them, did you rate them or leave any comments? If not, you should have http://www.babiess.info As previously mentioned, online video websites are a source of entertainment for many internet users. This is because many online video websites allow you to view their videos free of charge. Of course, there are some video sites that will charge you to become a member or charge you a fee for watching certain videos, but most are free to use. This is why online video websites offer the best possible source of online entertainment, because they are free to use or at least reasonably priced. When it comes to finding a video online, you will find that it all depends on the online video website that you are visiting. Videos that you should be able to find online may include, but should not be limited to music videos, homemade videos, celebrity interviews, sports recaps, and television shows. Most online video sites have a large collection of homemade videos. These videos are made by individuals, just like you. Many individuals go through a lot of trouble to make their own video and upload it to share with you. That is why it is advised that you rate all of the videos that you see and leave comments, if they are allowed. Perhaps, the most important reason why you should leave comments on a video website is to make your opinions known. Many internet users leave positive comments when they have viewed a video that they thought was well put together. In addition to positive comments, there are also internet users who leave negative comments, as well. If you were offended or left unsatisfied by watching a video, you can leave a negative comment. When leaving a negative comment, it is advised you be as tasteful as can be. You will not just want to say that the video stunk, but you may also want to offer helpful suggestions. Video makers love getting comments, especially those that focus on the positive points of their video, but that is not the only reason why you should leave a comment. There are a number of different online video websites that rank their member's videos in a number of different ways. Many online video websites rank videos by their user ratings, but others rank their videos by the number of comments that their videos have. YouTube is one of those websites. So, not only could you be making your opinions known, but you could also help to increase the ranking of the video that you just watched and enjoyed. As you can easily see, there are a number of different reasons why you should leave a comment on a video that you watched online. Although a fairly large number of online video websites allow you to post video comments, not all will. In the event that comments are not allowed, you will, at least, want to rate the video. Almost all video websites will allow you to do this. Mobile Ringtone Business October 11, 2009 at 10:00 am The Mobile phone Industry has evolved drastically over the past few years. When the first cell phones rolled into the market in the 1990s, nobody ever expected that those bulky boxes would develop into sleek, beautiful and powerful machines that could (aside from sending and receiving calls) take a picture, make a video, and sing. Also, we hear now a different kind of ringtones either funny, song or regular ones. We find many websites full of ringtones for mobile which allow you choose what you like. Initially a technological wonder to connect with people to a sophisticated device effectively a part of your personality! What brought about this change? And who does it really benefit? The answer to the first question would be the outburst of the personalization trend and the changing consumerist demands. MP3 Ringtone Industry is a humungous industry for the simple reason that it allows you to make your mobile sing your favorite song when someone remembers you. A mobile phone with its contents has the ability to make you laugh, cry, happy, sad, and nostalgic and a lot more whenever you want it to. Although this wasn't the case a few years back. So how did it all start? The MP3 Ringtone syndrome!! Free MP3 Ringtones are readily available on the web and this has led to an increase in personalization. This desire to personalize mobile phones has established the present success of the mobile Industry. Today, when the marketing gurus see this impact of the Mobile industry on the masses, they take advantage of it. Many companies start to advertise their campaigns through mobile phones. Whether it is text messages to promote products and services or direct advertising through mobile music or mp3 ring tones, the rise in the number of mobile content providers reflects the success of many such advertising strategies. The Music Industry also benefits significantly. Statistics prove that mobile music downloads is growing by over 50 per cent every year. Artists become famous in the process. Musicians supplement their incomes and record companies celebrate at the revenue source. Mobile mp3 ringtones have in fact opened up a whole new revenue stream for record labels struggling with falling revenues and piracy. Many experts believe that in certain ringtone heavy markets, record labels will sign up artists with the objective of generating revenues only from mobile content. Other avenues would become secondary to it. The same holds true for the movie industry. Content like mp3 ringtones, wallpapers, and ring back tones based on films is a huge draw and is today a large part of revenue forecast plans of movie studios. The mobile content has also spurred a whole new content industry; several small and medium enterprises have been set up to develop content specifically for the mobile phone platform. At the centre of this axis is the telecom carrier, who takes a significant share of revenue for each mobile content download. Telecom carriers too have set up separate mobile content / VAS divisions to harness the revenue potential of the medium. The mobile mp3 ring tone industry has its own ecosystem, with each player drawing its share of revenue from every ring tone that gets downloaded by the user. The Best Way to Clean Printer Ink Cartridges October 11, 2009 at 10:00 am As we know, anyone use computer needs for a printer to print out whatever he/she wants either for work or school. Also, each part in the printer is sensitive and must to handle it carefully. Because printer ink cartridges are so expensive, it is important to make your inkjet last as long as you can. Instead of replacing a clogged or dirty inkjet, you can manually clean it yourself to get it back into good working order. The following is a guide on how to clean your printer ink cartridge: 1. Before you start the process of cleaning the cartridge, find out the type of cartridge that have. Most HP ink cartridges have the print head on the cartridge, but other brands may be a bit different. Check your owner's manual or check the website for specifics. The information will tell you what part of the ink system you need to clean. It will always be the print head that you will clean, so it is important that you know where it is located. 2. Use filtered, bottled, or distilled water, and then dip a cotton swab into the warmed water. Wipe around the nozzle plate with the swab. Make sure that you clean center of the ink cartridge as this is the actual nozzle plate. Also, do not touch the copper colored areas as they are very fragile. If the swab gets too filthy, use another clean swab dipped in the water until there is no sign of any debris in the area. 3. Remove the cartridge from its holder. If you have a cartridge with the print head on it, run under hot water for 10 seconds. Let the ink cartridge dry for a few minutes before you insert it back into the printer. 4. To clean the printer head nozzle, set the cartridge on the work surface with the ink surface nozzle facing up. Moisten the swab with distilled water. Make sure to squeeze out any surplus water from the swab. Wipe the surface of the nozzle tip with the swab. 5. Dry the cartridge with a soft cloth. Wait until completely dry and then reinstall. If that does not work, remove the cartridge again. Moisten a cotton swab with glass cleaner and swab the print head. Dry with a soft cloth. 6. Reinstall the print cartridge to the printer. Align the print cartridge with your printers alignment function. 7. If your print head is inside the machine, you can repeat the same process as in Step 4. It is important to make sure that you let the print head air dry, or dry it with a cotton swab before using. It is important to clean your printer cartridge before using it and after an extended period of time. As well, do not use tap water as the impurities can damage the cartridge. For particularly difficult dirt and clogs, you can soak the print head in Windex overnight, dry it off completely, and then reinstall. To maintain your inkjet and avoid constantly cleaning it, you can just run a few test pages on your printer once a week to preserve ink flow. Cleaning your printer ink cartridge is much easier and cheaper than going out to buy a new cartridge. Steps to Put New Ink in a Printer Cartridge October 11, 2009 at 10:00 am An ink cartridge, or inkjet cartridge, is a replaceable piece of an ink jet printer that contains the ink. Each ink cartridge contains one or more divided ink reservoirs. Replacing an ink jet can be expensive, especially if you do a lot of printing or copying. Fortunately, many manufacturers have developed refillable ink for ink cartridges. Most often, people can save up to 50% or more over a replacement cartridge. The Ink jet refill kits contain easy to use tools and easy to follow instructions for refilling an ink cartridge. The following are general instructions to putting ink in a printer cartridge: 1. Buy an ink refill kit at an office supply store, computer store, or department store. 2. Gather all of the materials you will need to refill the cartridge. This can include: syringe, latex gloves, and paper towel 3. Remove the empty cartridge from the printer. Depending on what type of printer you have, there may be a particular method of cartridge removal. Refer to your printer manual on how to refill a unique type of ink cartridge. 4. Place the empty cartridge on a piece of paper towel. 5. Find the fill holes on the top of the cartridge by sliding your finger across the label. 6. Use a pencil or tooth pick to puncture the refill holes in the top of the ink cartridge. 7. Insert the long needle of the syringe on the refill ink bottle into the correct hole. 8. Little by little, add the ink. It is important to make sure that you do not over-fill. It is usually 10 cc for black ink and about 5 to 8 cc for colored ink. 9. Stop when you observe ink coming out of the hole. Remove the needle from the hole after expelling any remaining ink. 10. Carefully pat the cartridge contacts on the paper towel to observe a spot of ink leaking out. 11. Cover the hole with a tiny piece of clear tape. Make sure you do not transfer the colors. Repeat steps for each ink color. There are three colors of ink: magenta, cyan, and yellow. Follow the instructions on which hole to insert each color or push a toothpick into the holes to ascertain the colors as the markings on the printer cartridge 12. Put the ink cartridge back into the printer. 13. Leave the ink cartridge in the printer for about 12 hours before using it. This will permit the sponge inside the cartridge to become uniformly soaked with the ink. 14. Print several test pages to make sure the ink is running. There are a number of different methods to refilling your ink cartridge. The benefits of refilling include that they are much cheaper than replacing a used cartridge with a brand new cartridge, and they help keep ink out of the environment which is toxic to the soil. You also will help reduce the amount of garbage going into the landfill. The next time your ink cartridge runs out of ink, consider purchasing an ink refill kit. Recover your Data after Virus attacks October 11, 2009 at 9:59 am Virus is a threat to every computer whether used at home or in any organization. Does a virus attack your computer and make you confused? . Most of us must have encountered a data loss after a virus attack on our computer. Those who haven't may face a virus attack in future. A virus basically is a computer program, which is capable enough to destroy the entire data saved in the hard drive of a computer system. Who creates these computer viruses? Programmers with good knowledge of various computer programming languages create such malicious applications, which are intelligent enough to target certain loopholes like open ports, code vulnerability etc. of the computer operating system or BIOS. What are the main causes and consequences of a computer virus? The main cause of a computer virus is the connection of the computer system to the internet. Most of the viruses attack the computers when a user is downloading any file from the internet. Viruses can attack your system when you are downloading an attachment (containing the virus) from your email. Installation of poor anti-virus software can also lead to virus attack on your computer. If no firewall is installed on the computer or the network (hardware firewall) can result in virus attack. The main consequences of a fatal virus attack are as follows: 1) Loss of data viz. from My Documents folder in Windows as the viruses target files with certain extensions as well 2) Operating system file corruption viz. Windows/System/System32 folder files get infected in Windows 3) System performance degradation 4) Instable computer behavior In order to protect the computer from viruses, users install anti-virus software, firewall, and spyware. Out of the above consequences, the worst that a user encounters is the loss of important data. In order to recover the lost and corrupted data, the user needs to use effective data recovery software. This data recovery software uses advanced scanning algorithms to restore the lost data, which has been affected by a computer virus. Stellar Information System Ltd. provides the finest data recovery software. The data recovery technicians at Stellar Information System Ltd. are equipped with good technical skills, which allow them to extract complete data from any storage device that is affected by a computer virus. These technicians perform data recovery process from the storage devices in sterilized surroundings in Class 100 Clean Rooms. Stellar Information System Ltd. has more than 1,000,000 customers worldwide and the list is increasing on daily basis. If there is any virus in your computer, don't worry about the important data you lost because you can recover them easily. What is The Best Tool for Video Editing? October 11, 2009 at 9:59 am The best technology nowadays is computer. Computers were designed to make things easier for us and a lot faster. That is also true with using computers for video editing. Computers are being used for video editing nowadays because it saves a lot of time. If you are familiar with computers it will be a lot easy and you can finish the job in about an hour. Using computers for video editing is known as Digital Video Editing. All you have to do is just take a video or a shot then connect your camcorder to the computer. After that you can start editing it and add whatever filters or titles you want to put. The computer will play an important part in making you video a good one. You have to download or install video editing software first. Also, check your computer. You must have a CPU processor that is fast. The CPU processor is the life of the computer for this is where information is stored. As like what they say the muscle and the brains of a computer. If the CPU is fast, it will produce better edited videos and you could check or preview the video at present time. Large Hard Drives is also a must in using computers for video editing. You will not only use software for editing but usually the files of the video are large therefore consuming a large space on your hard drive. This is essential in creating a high quality video. It is also recommended that you get an external hard drive so that you will still have enough space for your computer's hard drive. It is a good way to store your videos if you use an external hard drive. A factor to consider is the RAM that you have in your computer. It is one of the factors that will give your computer a good performance as well as create a good quality video. You may use 1GB of RAM but if you can upgrade it to 2GB it will be better. Hardware equipment for video editing has two kinds: analog and digital. We use video capture card for analog format. This will transfer analog picture from your computer to other sources like television, analog camcorder and VCR and will format it to digital video. Firewire is also available and in demand. This video editing hardware equipment allows us to transfer the video in digital format thus making us capture the video digitally and would not have to go to the process of transferring video from analog to digital format. With digital video editing we can make simple videos like your summer vacation or a special occasion a quality video. Chances of making a documentary film is also big just by using digital video editing. It is less expensive. Also, the image quality will not diminish since we are using digital format. We can further enhance the video instead of making it poorer in quality. Computers will make your video editing faster, easier and would produce quality videos that you may benefit in the future. Enjoy the advantages that computer allows you to edit your videos and make whatever you like by the computer and its programs. Computer Checkup October 11, 2009 at 9:57 am The more you use your computer, the slower it seems to get. At least, that is the general consensus among many average computer users. It is a pretty common phenomenon to see a computer that is mainly used for checking email and playing solitaire eventually bog down to nearly a grinding halt. Also, we preserve many files and documents and download a lot of videos and sounds. The problem is that these computers are not broken, as many owners would assume, but they are simply clogged with garbage, such as spyware or the occasional computer virus. So the question comes up, when was the last time you ran a good computer checkup on your system? As the saying goes, well, that is too long. You can always disconnect your computer tower and drag it down to your local computer repair shop and hope that they will not charge you very much to check it out. The truth is, they most likely will. Part of that will be labor, which can run you anywhere from $30 per hour and up. Most people are not aware of it, but it is very easy to perform a computer checkup on your own. And it is also a whole lot cheaper to do it yourself. A couple common fixes for a slow computer are very simple to perform. In fact, this can get your computer running nicely again in no time. First, you will want to go to the start menu and run 'msconfig'. Under the startup tab, you will want to uncheck any programs that are not necessary to Windows performance - and most of them are not. If you make a mistake, after a reboot you can always recheck the disabled program to start it again when you next power cycle your machine. This should always be your first step when doing a computer checkup where your system is running slowly. If you know what you are looking for, you can find all sorts of things in here that can slow you down, including viruses. It is good to be familiar with this trick. Second, you will most likely want to download a free spyware removal tool from a reputable internet site. Be sure to do your research, because there are many programs that pretend to be a helpful program, but in fact hide spyware of their own, trying to trick you into purchasing their product. Once you get your program, install it, upgrade the definition tables, and scan your system. Do not be surprised if you find a bunch of things...this is a common problem. Next, you will want to follow suit and download and install a good quality antivirus program. Also be sure to do your research and select a reputable program, because like anti-spyware programs, there are nasty bugs in disguise with these, too. Do a quick computer checkup with this as well. The last tip is a great one. Simply do the above, then drop in another RAM stick. You will see a very noticeable boost in computer performance, and with all of these steps you will have that good old system back up in no time. So try to checkup your computer from time to time in order not to make it runs slowly. This will help to make your computer as a new brand. What is the Benefit from Internet Computer Games? October 11, 2009 at 9:57 am Have you ever think to play a computer game? A number of people play computer games as computer games are fun-packed and allow players to enjoy their time. Computer games are also very exciting and this is one of the reasons of the popularity of computer games. Playing fun-packed computer games is one of the best ways to kill the time and to relax. However, not everyone is in the favor of computer games as people usually spend a lot of time on computer games because of the excitement and fun offered by them. Also, an individual usually forgets about the real-world problems while playing computer games and this is one of the reasons why not everyone is in the favor of games. However, computer games have a number of benefits as well, but it depends on the player whether he uses computer games in a correct way or not. Excess of anything is not good and this is also applicable to the time spend on computer games. It depends on an individual whether he uses computer games in a beneficial way or not. Benefits of computer games: An individual can improve the decision-making skills by playing computer games. In strategy based computer games, the player needs to make optimal use of limited resources in order to complete the missions. A plan has to be developed in order to use resources efficiently and to make a perfect plan, a number of things are to be considered and a number of decisions are to be made. Generally, the player needs to think ahead of the current situation and develop appropriate plans. The ability to think forward in real-life is very useful and the people who can think ahead of the current situation usually have the plans ready for handling different situations. Sometimes in a game, decisions are to be made with-in few seconds and so, the player needs to think fast so as to make a decision. So, individuals who are not very good at making strategies and decisions can play computer games so as to improve the decision-making skills. However, you should not expect instant results as it takes time to improve the skills and the time required to improve the skills depends on the mental ability of the person. Computer games also help individuals to improve their ability to memorize things correctly. Some games require players to remember the clues, maps, and the location in order to play the game easily. So, players try to memorize and re-collect various things while playing games. This helps them to remember and re-collect things easily in real-world. Remembering and re-collecting things in real-life is very useful and by playing computer games, an individual can improve his ability to memorize things. People who play computer games are found to have better eye-hand coordination than people who don't play computer games. While playing computer games, players need to use eyes and hands together. Players need to use hands to use the buttons which are required for performing different tasks available in the game and eyes are needed to see the game. The current situation of the game determines the task to be performed and so, the player needs to use hands and eyes together in order to play the game efficiently. Computer games help individuals to improve their ability to solve puzzles. A number of puzzle games are available which require players to think logically so as to solve the puzzle. So, people can improve their ability to solve puzzles by playing puzzle-based computer games. So, computer games can offer entertainment and improve people skills and abilities. Besides that, it gives them a wonderful time. What are the Color Laser Printers? October 11, 2009 at 9:56 am There are many kinds and shapes of printers and each one gives us a lot things. Nowadays, black-and-white color printing is replaced with color printing. Your business promotion can impress your client at a glance just by looking your presentation and advertisement. It's absolutely undoubted that Color is more attractive. The more color you take, the more eye catches you get. It doesn't mean that black-and-white color is not interesting. In some cases, it looks so classy. The other customer behavior now is that they are more interesting in laser printers than inkjet printers. Laser printers reduce the cost per page and the printers won't bothered you with it noise. Have you remember printing using dot matrix printer can be annoying because of its sounds. That annoying noise you won't get with laser printers. And now printer manufactures are race each others to get the biggest customer in markets. They produce so many types of color laser printers. All come with its own design and features. Then how you can choose the right printer for you in many types of Color Laser Printers? Some factor below may be your consideration before deciding. Resolution, which usually have unit called dpi (Dots per inch) function as number that show the color sharpness. The higher the dpi, the sharper color you get. If you use the printer more for text, choose at least 600x600 dpi. And for printing more than a text, use the printer with 1200x1200 dpi. And if your Color Laser Printers use network to share it, consider its memory. Check the RAM capacity of the Color Laser Printers and whether it's expandable. Related to networking, if your printer is for sharing, consider this feature. Another thing that you should consider is printer speed. In usual, it can be seen from its ppm (print per minute) and how long the Color Laser Printer takes to print the first page. For example, you need to print 100 pages at a time, if you using 8-ppm printer, it would take about fifteen minutes. But it only can be a minute with 35-ppm laser printer. This option you should consider if there is a need for printing a large amount of documents. Then, are you need to print the document in dual side? If the answer is yes, you should look the duplex printing feature. Some Color Laser Printer come with this function, but the price is more expensive. The last thing, you may consider about paper tray and paper size. Which paper size you often use? Standard Color Laser Printer usually provide for letter and A4 size. But if you or your business needs the bigger size, you should find the printer that can be used for large printing. The paper tray is useful to efficient your time. It can hold the paper, letterhead, or envelope. So you don't need to swap and refill the paper each time you printing. Start your search by considering all factors above. Then, perhaps you can find the most appropriate Color Laser Printer that will help your printing job.   This email was sent to blogpersonalcomputer@gmail.com.  Create Your Account Don't want to receive this feed any longer? Unsubscribe here.