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PICAXE VSM: The PICAXE Circuit Simulator! Ever wondered whether your latest scathingly brilliant PICAXE project idea would actually work? Well, now you can find out before you build it, with the new PICAXE circuit simulator software! Mr PICAXE, Clive Seager, talks us through the latest PICAXE software offering from Revolution Education. Fig.1: circuit simulation of the AXE107 Rudolph Project Kit (SILICON CHIP, September 2004). What you can’t see from the screenshot is the “Rudolph the Red-Nosed Reindeer” tune playing from the piezo (simulated via the computer’s speaker)! 28  Silicon Chip siliconchip.com.au Fig.2: the program can be stepped through line-by-line and variable values studied on screen. P ICAXE Virtual System Modelling (VSM) is a new software circuit simulator that combines a “virtual” PICAXE chip with animated components and Berkeley SPICE circuit analysis to produce a simulation of a complete PICAXE project – and it operates in real time on most modern computers! PICAXE VSM is a joint venture between two UK companies, Revolution Education, the developers of the PICAXE system, and Labcenter Electronics, a world leader in circuit simulation products which has been producing commercial SPICE and microcontroller simulators for almost 20 years. To use the system, you first draw your circuit schematic on screen, using the library of over 10,000 popular analog/digital components and automated wiring to build up your circuit. You then associate your PICAXE BASIC program to the PICAXE chip component and click “Play!” to watch the circuit in operation! siliconchip.com.au On-screen animation & virtual instruments The on-screen output components (eg, LEDs, motors and displays) all animate as the PICAXE program runs and input devices such as LDRs, temperature sensors, switches and keypads can be activated by clicking on the animated model in the circuit simulation. This allows the user to interact with the circuit as the program runs. Fig.3: a sample “virtual oscilloscope” trace. January 2008  29 sible to download additional models from manufacturers’ websites to use within VSM. All supplied component models can also be “decomposed” and then “rebuilt”. This allows the user to reconfigure the pin layout of a schematic symbol if it is not laid out as you desire. Another advantage is that this allows the user to edit animated models. You can generate your own “orange LED” model by decomposing the supplied “red LED” and changing the colour of the individual animation frames from red to orange. Conventional (non-PICAXE) circuits Fig.4: sample input/output animated components, including an LDR, a switch, a 7 segment display, a piezo buzzer and a motor. VSM also provides extensive debugging facilities – the PICAXE program can be stepped through line-by-line; breakpoints can be set in the program and the variable values can be displayed on screen. VSM also contains a number of virtual instruments including a voltmeter, ammeter, oscilloscope, signal generator, logic analyser, timer, serial terminal and I2C and spi debuggers. So, for instance, you can connect an oscilloscope probe to the “simulated” infrared sensor and watch the infrared demodulation on the oscilloscope trace. VSM also supports “traditional” components such as 555 timers, op amps, logic gates, etc. These components can be simulated in circuits by themselves or combined Fig.5: alternative PICAXE-08M schematic symbols used in PICAXE VSM, dependent on user preference. PICAXE components VSM is supplied with a library of over 10,000 components and supports all the major protocols including RS232, spi, I2C, 1-wire, etc. As well as all the conventional components (resistors, capacitors, LEDs, transistors, etc), the software supports many advanced components not often found in other simulation products; eg, I 2 C EEPROMS, iButtons, digital 1-wire temperature sensors, serial LCDs, stepper motors, radio-control servos and in fact, all the commonly used PICAXE interfacing devices! VSM supports the popular Berkeley SPICE model format, which many electronic manufacturers provide for their components and so it is also pos30  Silicon Chip Fig.6: one of the free op amp tutorials. siliconchip.com.au Fig.7: Bill of Materials exported from PICAXE VSM in CSV format. into a PICAXE circuit. The software also includes a series of over 75 free “electronics principles” tutorial files which explain the operation of logic gates, timers, op amps, etc. VSM can also be customised to your own preferred graphics. As can be seen from Fig.6, a customised dark background helps highlight the current and voltage colour coding of the animated wires when a simulation is run. Netlist and Bill Of Materials export VSM can export a Bill of Materials for the circuit schematic and can also generate a netlist that can be imported into a PC board layout application to generate a board design. A dozen different netlist formats are Fig.8: AXE110 Datalogger Circuit, simulating three advanced protocols – RS232, 1-wire and I2C – in one design! available, including popular freeware PC board layout applications such as Eagle. stored data to be uploaded when the datalogging session is complete. Example VSM circuit A single user licence for PICAXE VSM costs $AU115. Licences are delivered by email. To buy online, or for further information including a free demo version, please visit the PICAXE VSM website at SC www.picaxevsm.com The model shown is of the AXE110 PICAXE-18X datalogger, which was described in SILICON CHIP between January and March 2004. An animated LDR and DS18B20 temperature sensor provide the inputs to the system, while the data is saved to an I2C EEPROM memory chip. The AXE033 serial LCD module shows the current temperature and light readings, and the DS1307 realtime-clock allows the datalogger to take samples at specific time/date slots. Finally the RS232 link allows the Further details COMING NEXT MONTH In our February issue we will look at a step-by-step tutorial on how to build up a PICAXE circuit from scratch using PICAXE VSM. Radio, Television & Hobbies: the COMPLETE archive on DVD YES! A MORE THAN URY NT QUARTER CE ICS ON OF ELECTR HISTORY! This remarkable collection of PDFs covers every issue of R & H, as it was known from the beginning (April 1939 – price sixpence!) right through to the final edition of R, TV & H in March 1965, before it disappeared forever with the change of name to EA. For the first time ever, complete and in one handy DVD, every article and every issue is covered. If you’re an old timer (or even young timer!) into vintage radio, it doesn’t get much more vintage than this. If you’re a student of history, this archive gives an extraordinary insight into the amazing breakthroughs made in radio and electronics technology following the war years. And speaking of the war years, R & H had some of the best propaganda imaginable! ONLY Even if you’re just an electronics dabbler, there’s something here to interest you. Please note: this archive is in PDF format on DVD for PC. Your computer will need a DVD-ROM or DVD-recorder (not a CD!) and Acrobat Reader 6 or above (free download) to enable you to view this archive. This DVD is NOT playable through a standard A/V-type DVD player. 62 $ 00 +$7.00 P&P Exclusive to: HERE’S HOW TO ORDER YOUR COPY: SILICON CHIP siliconchip.com.au BY PHONE:* (02) 9939 3295 9-4 Mon-Fri BY FAX:# (02) 9939 2648 24 Hours 7 Days <at> BY EMAIL:# silchip<at>siliconchip.com.au 24 Hours 7 Days BY MAIL:# PO Box 139, Collaroy NSW 2097 * Please have your credit card handy! # Don’t forget to include your name, address, phone no and credit card details. BY INTERNET:^ siliconchip.com.au 24 Hours 7 Days ^ You will be prompted for required information January 2008  31