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Open-USB-IO: a universal I/O solution This hardware I/O board will let you drive a host of digital and analog I/O (input/outputs) via the USB interface on your laptop or desktop computer. Based on an Atmel Atmega32 microprocessor and not much else, it works on Windows, Linux and Macs. I n the days of Windows 98 and DOS, you could directly write to the hardware ports on your computer, typically to the parallel printer port and serial port. This was great for hobbyists and many good projects were built around programs which directly accessed hardware. I built a very useful logic analyser that worked at 1MHz just by reading the digital inputs of the parallel port. I also controlled a bank of relays with C code, writing to the parallel port. Then came Windows XP, a great improvement over Windows 98, except that it blocked direct access to hardware ports. There was a quick and dirty fix called giveio.sys but it wasn’t always reliable. Next, parallel and serial ports started to disappear from laptops and even desktop PCs. Finally, along came Window Vista which has completely blocked I/O access. Thus hobbyists have been deprived of a powerful, simple, and cheap way to access hardware from program code. This inability to easily control hard26  Silicon Chip ware is not just a problem for hobbyists. At RMIT University where I lecture, we had the same problem with our labs and major projects. In the Computer and Networks degree, students need to become familiar with hardware, software, networks and the interaction between hardware and software (optional in Electrical and Electronic and Communications degrees). In our quest to find ways for software to control hardware we found several USB boards that allowed digital input and output (I/O) but they were either expensive, didn’t do all we wanted, didn’t work on Windows and Linux and Macs or needed special drivers to be installed. We drew up the specifications for our ideal hardware I/O board: • Cheap, under $50 in bulk. By Dr Pj Radcliffe Senior Lecturer, School of Electrical & Computer Engineering, RMIT University. • Lots of digital I/O, analog inputs and PWM outputs. • Basic I/O: LEDs, a Light Dependent Resistor (LDR) and a trimpot for simple analog work. • An RS-232 serial data port not used for any system function such as programming. • The ability to drive DC motors or stepper motors (at least 500mA and 50V each). • USB-driven, with no special drivers for Windows, Linux and Mac. • Hardware I/O can be controlled from the PC via a GUI, command line or program code. • Some prototyping area. • Interface with simple hardware using easy-hooks, or complex hardware with a cable. • All ICs in sockets to allow easy repair if they are damaged. • Users must be able to download their own code into a powerful microprocessor. Hardware can thus be controlled direct from the microprocessor with the USB just providing power. siliconchip.com.au JTAG ICE INTERFACE STK200 PROGRAMMING PORT USB TO PC RS232 MOTOR POWER RESET TRIMPOT ATMEGA32 NEW PIC TO COME ALL I/O ON IDC PINS LDR 8 SWITCHES PROTOTYPE AREA 8 LEDS Reproduced here significantly larger-than-life for clarity (it’s actually 125mm wide), this is the Open-USB-I/O Board showing key interfaces. • The whole thing should be Open Source and GPL for both software and hardware. This makes it easy for anyone to modify and extend the hardware or software but they must release these changes back into the public domain. It also keeps the price down as no one manufacturer can have a monopoly on the board. The result is the Open-USB-I/O board. Let’s look at its key features and then see how to drive it. What’s on the Open-USB-I/O The compact PC board packs a lot of features. Its heart is an Atmel ATMEGA32 microprocessor with 32KB of code memory, 1KB of EEPROM and 2KB of RAM. You can do a lot with 32KB of code memory! It also has three timers, four PWM (Pulse Width Modulation) lines, eight A-D converter ports with 10-bit accuracy, serial data ports, digital I/O ports and much more. Open-USB-I/O makes many of these available to the user but a few must be siliconchip.com.au kept to drive the interfaces such as the USB and the programming port. The board has eight LEDs and eight switches which can also be used as eight digital inputs and eight digital outputs. In fact these 16 lines can be used as any combination of inputs and outputs by reprogramming the data direction registers in the microprocessor. Above the LED array there is a LDR (light dependent resistor) which is read via one of the analog inputs on the microprocessor. The LDR can sense the output of nearby LEDs which gives interesting possibilities, including an optical oscillator. The trimpot in the middle of the board is connected to another analog port and provides a convenient variable analog input. Near the trimpot is a space where the user can add an additional 2-pin device, such as a buzzer. Circuit description The full circuit of the Open-USB-I/O board is shown in Fig.1. Only three IC packages are used: IC1 is the MAX232ACPE RS232 interface chip; IC2 is the Atmel Atmega32 microprocessor and IC3 is the ULN2003A Darlington array. The top left shows the USB interface where the zener diodes ZD1 and ZD2 act as voltage limiters while the 68resistors present the correct load to the PC USB port. The USB lines carry both DC power and high frequency data signals. Inductor L1 and the associated capacitors filter out noise to provide the DC rail, VCC. On a desktop computer the USB port can supply up to 500mA but laptops can provide rather less. VCC is clean enough for digital circuits but has too much noise for analog circuitry so the combination of inductor L2 and the 100nF capacitor gives extra filtering to provide the AVCC rail which is used for all the analog circuits in IC1. The USB data interface is handled by firmware on the ATMEGA32 which uses interrupt PD2 and pin PD7 to receive or drive signals to the USB line. The bottom right of the circuit has S2-S9, a bank of eight switches which can be read by the microprocessor. The October 2009  27 Vcc A 1.5k Vbus K 68 D– 21 GND 68 D+ K 16 K ZD2 3.6V A Vcc K Vcc RST 4 6 8 C5 100nF Vcc RST PC2 PC4 PC3 PC5 8 2 10 X1 12MHz C3 27pF C7 1 F C8 1 F RS232C CON11 (J11) 7 8 9 1 2 3 PD5 PB7 PB6 IC1 ATMEGA32 DSR RxD RTS TxD CTS 4 5 12 32 2 PIEZO LDR1 1 17 20 18 19 8 7 6 PB5 PB4 5 4 PB3 3 PB2 2 PB1 PB0 1 PC0 PC1 PC2 PC3 PC4 PC5 PC6 PC7 X1 40 39 38 37 36 35 34 33 22 23 24 25 26 27 28 29 X2 C4 27pF 16 2 6 1 6 PD4 13 Vcc PD6 RST EDITORIAL NOTE: This circuit does not have any protection for the inputs to the IC1 processor; voltages of more than 5V can damage the input. A series resistor for each input would provide protection, as the input clamping diode within IC1 will be current limited. Also, the power input for open collector drives at CON1 does not have reverse polarity connection protection and a reverse supply can destroy the IC3 clamping diodes. 10 5 9 7 PD3 9 RESET S1 PB5 PB7 PB6 1 3 47k A 7 9 4 6 PA0 PA1 PA2 PA3 PA4 PA5 PA6 PA7 D1 PA6 VR1 10k CON9 (J9) 1k 47k PD2 A 3 ICE/JTAG CON8 (J8) ARef PD7 ZD1 3.6V ICSP & TIA COMMS CON7 (J7) 2 5 1 30 AVcc 10 Vcc  LED1 1 2 3 4 AVcc C2 100nF PA7 CON6 (J6) C1 100nF 1k Vcc L1 10 H L2 10 H  USB SOCKET Vcc C6 10 F 3 4 IC2 MAX232 5 14 T1o T1in 11 7 T2o T2in 10 13 R1in R1o 12 8 R2in 15 R2o 9 C9 1 F A C10 1 F 15 K 14 A  K A  K A K A   K A  K A  K  K PD1 PD4 10k A  LED9 LED2 PD0 9x220 PD6 11 31 CON10 (J10) 1 RN2 2 Fig.1: the circuit diagram for the Open USB I/O module shows it is primarily based on a programmed ATMEGA32 along with several input/output devices and LED indicators. The various input/output and power connectors are labelled here as CON1, CON2, etc, as is our normal practice. However, on the PC board overlay and in the text of this article they are labelled J1, J2 etc, so we have shown both to avoid any confusion. 28  Silicon Chip siliconchip.com.au AVcc CON3 (J3) PA0 PA1 PA2 PA3 PA4 PA5 1 2 3 4 5 6 PA7 PD3 PD6 8 9 10 11 12 13 14 15 16 17 IC3 ULN2003A 18 19 20 1 1B 1C 16 2 2B 2C 15 3 3B 3C 14 PB4* 4 4B 4C 13 PB3* 5 5B 5C 12 PB2* 6 6B 6C 11 PB1* 7 7B 7C 10 PB0* E 8 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 7 PD4* PD5* COM POWER FOR OPEN COLLECTOR DRIVES Vcc CON1 (J1) 9 PORT C 8 DIGITAL INPUTS (OR OUTPUTS) PORT B 8 DIGITAL OUTPUTS CON2 (J2) 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 PB0 PB1 PB2 PB3 PB4 PB5 PB6 PB7 19 20 S2-9 9x 4.7k RN1 ZD1, ZD2 A SC 2009 LEDS K D1: 1N4148 A K K A K A OPEN USB I/O MODULE siliconchip.com.au 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 CON5 (J5) PC0 PC1 PC2 PC3 PC4 PC5 PC6 PC7 VSUPPLY PORT A ANALOG INPUTS, PORT D DIGITAL I/O (OPEN COLLECTOR OUTPUTS: 50V/500mA) Vcc CON4 (J4) 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 LOAD 2.7k 7.2k 3k Fig.2: the internal circuit of one ULN2003 driver. The diode connected to VSUPPLY stops inductive spikes from destroying the chip when a load is turned off. microprocessor provides internal 100k pull-up resistors on each port C pin. These set each port C pin to logic high when the associated switch is open and logic low then the switch is closed, bringing the external 4.7kpull-down resistor (resistor array RN1) into play. These inputs are available on the J4 connector (and the J2 holes below the connector). Any external output capable of driving the 4.7k resistor could be connected here and be read by the microprocessor. If all the switches were set to off the external input would only have to drive the 100k pull-up resistor. Port B of the microprocessor drives eight LEDs (LED2-9, labelled on the PC board DS2-DS9) through a 220resistor array and then via link J10 to 0V. If the link is removed the LEDs will not light. This can be useful if port B pins on connector J5 are intended to drive external devices. Alternatively, the LEDs may be left connected when driving external circuitry, as the ATMEGA32 outputs are capable of driving 20mA and the LEDs only take around 12mA, thus leaving spare drive for external devices. The ATMEGA32 should not drive more than 200mA for the entire chip as an absolute maximum but given the chip only requires some 12mA for its internal uses this leaves a Controlling Open-USB-I/O from the command line [user]$ ousb io PORTB 85 PORTB = 85 [user]$ ousb io PORTB 0xff PORTB = 255 [user]$ ousb io PINC PINC = 1 [user]$ ousb -h io PINC PINC = 0x1 [user]$ ousb -b io PINC PINC = 0b00000001 [user]$ ousb adc 6 ADC6 = 119 [user]$ ousb adc 5 ADC5 = 481 [user]$ ousb io PORTB 0 PORTB = 0 [user]$ ousb pwm-freq 1 7000 PWM #1 on pin 4 operating at 5859.375000 Hz [user]$ ousb pwm 1 30 PWM #1 on pin 4 operating at a duty cycle of 0.301961 October 2009  29 J7 J11 J6 MOTOR POWER L1 4148 47k 1k 47k L2 lot of drive for external devices. The RS232 interface at the bottom left of the circuit uses C7 1 a standard MAX232 chip to C1 RESET + C5 C9 + 4148 1.5k 4148 interface to the RS232 lines and MAX232ACPE C2 C6 68 X1 + + + to provide the ±3V power sup10k C3 C4 68 C8 C10 plies needed to drive the RS232 LSI outputs. The device not only J9 VR8 ULN2003A handles transmit and receive ATMEGA32 1k but also one status line in and one status line out. If the RS232 J5 port is not needed for serial 1 data, then the two output lines J4 can be used as general purpose 1 outputs that drive around +3V RN1 RN2 and --3V. J10 BREADBOARD PROTOTYPE AREA AREA The right side of the circuit ON DIP LDR LED1 shows the open-collector drive POWER A 1 2 3 4 5 6 7 8 chip, ULN2003A, which has LEDS 2-9 DIP SWITCHES 1-8 seven open-collector drivers. A A A A A A A A Fig.2 shows the circuit of one Fig.3: PC boardONLY layout, looking from top (component side). The PC board is TOP (COMPONENT) SIDEthe OF PC BOARD SHOWN FOR CLARITY of the Darlington drivers. An double-sided but the bottom tracks are not shown for clarity. input of 3V or more applied to the 2.7k resistor will turn on the Darlington transistor and current such an arrangement a signal on one the microprocessor and hence every can flow from VSUPPLY through the wire will usually create glitches on the hardware interface. load to ground. If the input goes to 0V wire next to it in the cable. The ISP socket conforms to the the Darlington turns off and the load The pins on the 20-pin IDC arrays older STK-200 programming interface current drops to zero. can be connected via easy-hooks or standard which is supported by many If the load is inductive, the built-in a proper cable, as can be found in programmers. Using this you can downdiode connected to the positive supply older computers (often on the side load your own code into the microwill short-circuit the inductive current of the road) that use IDE drives. The processor or reload our USB interface and ensure there are no large voltage right connector also has seven opencode. spikes that could destroy the chip. collector drivers powered from the The JTAG interface allows an In VSUPPLY is not tied in any way to motor power plug (top right of board). Circuit Emulator (ICE) to be conthe board +5V and can range from 0V The RS232 port provides a serial nected and provide powerful debugto 50V. The Darlingtons can handle data link that is entirely at the user’s ging facilities. Such ICE devices cost 500mA and so each of the seven driv- control; it’s not used for any programanywhere from about $50 to many ers can control a small DC motor or a ming or control function. hundreds of dollars. coil in a stepper motor. The USB socket takes a standard If you are doing serious developOur students at RMIT have used USB A-B printer cable which provides ment work that needs debugging, then such a configuration to drive one +5V power from the PC. Code on the an ICE can save you a lot of time by 6-wire stepper motor (using four out- microprocessor enables the board making it much quicker to find errors. puts) and three DC motors or servo to act as a standard USB device and You won’t need either of these sockets units. The power for these motors is allows the ousb program on the PC if you just want to control the I/O usually connected to the 2.5mm DC to directly control every register in ports from your PC. (Editor’s Note: for socket (centre pin positive) which corresponds to VSUPPLY above. If you use the USB +5V as described BASH script file example above and your commands to Open#!/bin/bash USB-I/O start to generate errors, then # it is likely that the output devices are #----- BASH script to read the LDR light sensor and drawing too much current from the write the value to the LEDs. USB port. set –u # stop autodeclaration of variables. The two 20-pin IDC connectors, J4 LDR= & J5, provide access to most of the until [ 0 != 0 ] # A forever loop, control-C from the keyboard to stop. microprocessor pins and all the opendo collector drivers. The back row of these sleep 0.3 # pause for 300 ms. pins are all connected to 0V. When a LDR=$(ousb adc 6) # get the LDR reading from Open-USB-I/O cable is connected this means each let “LDR = LDR/4” # scale the 10 bit ADC back to 8 bits. signal wire has a 0V wire on each side. ousb io PORTB $LDR # write the value to the LEDs This helps to stop interference both done to and from the signal wire. Without J8 30  Silicon Chip siliconchip.com.au more on JTAG see the review article on pages 44-48 of the August 2009 issue of SILICON CHIP). Lastly, the prototype area is big enough to add your own hardware, for example a motor, a relay or a number of opto-isolators. Obtaining the software and hardware There are several key resources that will help you understand much more about Open-USB-I/O and provide all the required hardware, programs and circuit diagrams. The web site http://pjradcliffe.word press.com/ has: • A reference manual which covers the USB commands in more detail, how to program the board from script files (.bat under Windows or BASH under Linux), how to write and download your own C programs onto the ATMEGA32 and a description of various development tool chains. • The Windows and Linux programs that give the ousb command line functionality described later in this article. Normally the firmware is pre-programmed into the OpenUSB-I/O board but the web site has the firmware and instructions on how to program it into the board. • Hardware circuit diagrams for the Open-USB-I/O board and a simple programming cable which enables you to download your own programs into the board. The web site http://interestingbytes. wordpress.com/ supplies the OpenUSB-I/O boards and also has a liveDVD with a huge range of development tools. This bootable DVD provides an excellent and surprisingly easy to use Linux system running straight off the DVD. Live-DVDs do not touch the hard disk, they run from just your DVD drive and the RAM. However, if you like the live-DVD then it takes only 15 minutes to install it as a dual boot to the hard drive. To boot the live-DVD ensure your BIOS is set to boot first from DVD, then put in the DVD and restart the computer. When the desktop appears double click on the readme.html file and read through the help and howto information. Key features on the live-DVD related to the Open-USB-I/O board include: • Code editors and avr-gcc C comsiliconchip.com.au How to connect your circuitry to Open-USB-I/O piler and assembler for Atmel microprocessors. • The VMLAB emulator that enables you to simulate your code, including hardware, before downloading the code to real hardware. • An excellent set of examples which can serve as the basis of your own projects. • A variety of useful documentation, including all data sheets for the ATMEGA32 and Open-USB-I/O board. The live-DVD has an extensive array of other development tools for Linux including the Eclipse IDE for C, C++, java, python, Perl, and C for the ATMEGA32. Other tools include Apache web server, MySQL database server, PHP, web editors such as Kompozer, Qt Designer for GUI development and much more. There is also a whole range of network tools, drawing tools, Open Office, audio-visual programs, and a few games. Construction The Open-USB-I/O is available in kit form or built and tested. The preassembled version is only slightly more expensive than the kit version and available from http://interestingbytes.wordpress.com/. However, any hobbyist with reasonable soldering skills should be able to build the board themselves. The following is for those constructing from a kit. Using the component layout of the PC board (Fig.3), start with the IC sockets, ensuring that pin 1 of each is properly orientated. The notch at one end of the socket should match the notch in the socket outline on the board. Next, solder in the sockets on the back edge of the board, the two shrouded IDC connectors, the USB connector, the RS-232 connector and the DC power connector. Note that the notch in the two shrouded IDC connectors should face the outside of the board. As you solder in the two 20-way IDC connectors, be careful that they are sitting flush to the board and solder one pin on each end first. Do not apply heat for too long to any pin as the plastic can melt and the pin will shift, making it impossible to place a plug into the socket. Now it is simply a matter of placing and soldering in the rest of the components, starting on one side of the board and moving to the other side. Be especially careful with all polarised devices such as electrolytic capacitors and LEDs. Finally, insert the ICs into their respective sockets (again watch the polarity) and do a careful visual inspection, checking the board against the photos and the overlay diagram of Fig.3. Don’t forget to put in link J10 directly above the LEDs or the LEDs will not light! Power up by connecting the board, via a USB cable, to a powered-up computer. The yellow power LED should October 2009  31 immediately light. If not, check for shorts between +5V and ground on the board. Start playing The simplest way to control the Open-USB-I/O board is via the command line. On a Windows computer copy the ousb.exe file from http://pjradcliffe. wordpress.com/ to My Documents. Start a terminal by clicking the start icon, select Run, then type cmd in the command box and hit enter. Use the command cd “My Documents” (change directory) to move to where you have saved the ousb.exe file. For Linux, copy the ousb file to some where convenient. The location /usr/ local/bin is a good place for programs as this is in the path. Another good place is your home directory. Check the program works by typing just ousb in the command window, help information should be displayed (if you are using your home directory on Linux use ./ousb). To begin, let’s control the LEDs. First, ensure link J1 directly above the LEDs is plugged in. Type the command ousb io PORT B 85 and every alternate LED should be lit. This command is writing to PORTB of the microprocessor which is connected to the LEDs. Now try ousb io PORTB 0xFF which will light all LEDs and uses a hexadecimal number with all bits set high. To turn off the LEDs, use the number 0. Next try reading the switches, first set all switches to ON and try the command ousb io PINC. The result should be zero. Now try setting any switch and issue the command again. The result should show a one bit for each switch turned off. To view it in hexadecimal try ousb –h io PINC, to see the result in binary try ousb –b io PINC. The LDR is a slow responding light detector. Try the command ousb ADC 6 to see the light level. Try different light levels and turning the LEDs on and off, to see changes in the reading. The trimpot provides a convenient analog input, use the command ousb adc 5 to read the setting. Try moving the pot and note the reading changes. If you have some easy-hooks and a small DC motor then you can use the PWM and the motor drivers. PWM generates a fixed frequency square wave but varies the ‘on’ period (duty cycle). A motor responds to the effective 32  Silicon Chip Connections to drive a small motor with the pulse width modulator. Inset top right is the J5 37-39 jumper required to drive the motor from USB port +5V. average voltage so if the duty cycle is 10% then the effective voltage to the motor is 0.5V and the motor will probably not even move. However, for a duty cycle of 90% (which translates to an average voltage of 4.5V), your motor will spin freely. There are two ways to get power for the motor. The first is to use an external power source that plugs into the 2.5mm DC socket (centre pin positive) on the board – in this case the motor can be connected between pins 27 and 37 of J5. The second approach is to use the +5V supplied by the USB which should be OK for a small DC motor. If you are using this method you will need to link pins 39 and 37 of J5. The photograph above shows both options. Note that the red and black connections are required for both, while the jumper between pins 39 and 37 of J5 (inset in red) is only required for option 2, in order to use the USB +5V to drive the motor. The first PWM output can only operate at four set frequencies and the output is connected to LED3 as well as an open collector driver. First set the LEDs to off using the command ousb io PORTB 0 and then set the frequency of the PWM to say 7kHz using the command ousb pwmfreq 1 7000. Note the frequency will be rounded to one of the several fixed values available. Now set the duty cycle to 50% with the following command: ousb pwm 1 50. LED2 should now be at half intensity. Try other duty cycles to see the intensity change, or if you have a motor connected then the motor speed will vary as the duty cycle changes. Advanced play The ousb io command allows the user to access any register in the microprocessor and so gain full access to all the on-chip peripherals which include extra timers, I2C interfaces, more PWMs, interrupts, input time capture, the RS232 interface and more. As an example let’s take port B which is an output by default and then make it an input. First use the command ousb io PORTB 255 to turn on all the LEDs. siliconchip.com.au Next, the data direction register for port B must be altered – use ousb io DDRB to read the current value, then ousb io DDRB 0 to turn all the pins to inputs which should turn off all the LEDs. Add the command ousb io PORTB 0 to turn off the microprocessor’s 100k pull-up resistors which may cause the LEDs to glow dimly. Now try the command ousb io PINB to read the inputs. Use an easy-hook or similar to connect the J4 pin for port B bit 0 (pin 21) to +5V (pin 37) or 0V (any even pin). Read the value of the pin using ousb io PINB. To restore the microprocessor to its default state first remove all connections and then hit the reset button. Any ousb command can be placed in a script file; a .bat file for Windows or a BASH script file under Linux or Macs. The Windows .bat files are not very powerful compared to Linux BASH script files. Under Windows you can download a package called cygwin (www.cygwin.com). This gives you a Linux command line and BASH script capability on Windows. With a BASH script you can now write complex programs to control your Open-USB-I/O board. For example, the bash script file earlier reads the Light Dependent Resistor and writes the reading to the LEDs. Starter projects to power projects The ATMEGA32 is a cheap yet very powerful microprocessor and quite amazing things can be done with it. The web is filled with the hardware and software that you can download for free. For example, Neil Franklin on his website http://neil.franklin.ch/Projects/SoftVGA/ shows how to drive a VGA display from the ATMEGA 32 with just six resistors. Austin Lu and Albert Ren show to build an iPod interface (http://dev.emcelettronica.com/ how-to-control-ipod-atmel-mega32). Perhaps you are just beginning, how about just flashing a LED (at www. dharmanitech.com/2008/10/adcproject-with-atmega32.html). Some of the best projects and information can be found at www. avrfreaks.net; here you can find tools, data sheets, getting started information and projects ranging from the simple to the extreme. Low speed activities (below 1kHz) can be driven from the PC via comsiliconchip.com.au mand line, script, or C/C++ code. Higher speed activities need to be programmed directly on the ATMEGA32 microprocessor. Conclusion The Open-USB-I/O board is an easy and inexpensive way to achieve digital and analog I/O from your laptop or desktop using just the USB port. It will work on Windows XP, Vista, Mac OSX, Linux and other POSIX operating systems without the need for special drivers. The board contains a whole range of I/O pins, Pulse Width Modulators, analog inputs, motor drive pins, and more. The board also contains the powerful ATMEGA32 microprocessor and using the live-DVD you can write your own assembler or C code then download it into the ATMEGA32. The live-DVD has several project examples which can serve as the basis of your own projects. We have found the Open-USB-I/O board very useful at the School of Electrical and Computer Engineering at RMIT University (Melbourne, Australia). It can be used in simple first year programming activities right up to final year microprocessor subjects that require students to use the full complexity of the ATMEGA32. The board is used in our major project activities which are both fun and very important to our students (employers want evidence that students can achieve things not just be good at passing exams!). Hopefully you will find Open-USB-I/O as useful as we have. We are developing more useful tools based around Open-USB-I/O including a GUI controller and the ability to program the ATMEGA32 just through the USB connection. Check the websites below in the near future to get these tools. SC JOIN THE TECHNOLOGY AGE NOW with PICAXE Developed as a teaching tool, the PICAXE is a low-cost “brain” for almost any project Easy to use and understand, professionals & hobbyists can be productive within minutes. Free software development system and low-cost in-circuit programming. Variety of hardware, project boards and kits to suit your application. Digital, analog, RS232, 1-Wire™, SPI and I2C. PC connectivity. Applications include: Datalogging Robotics Measurement & instruments Motor & lighting control Farming & agriculture Internet server Wireless links Colour sensing Fun games Where do you get it? See www.interestingbytes.word press.com to purchase an OpenUSB-IO board and the live-DVD which contains development tools and example projects. See www.pjradcliffe.wordpress. com for a detailed reference manual, and all the programs that you will need. Distributed in Australia by Microzed Computers Pty Limited Phone 1300 735 420 Fax 1300 735 421 www.microzed.com.au October 2009  33