If you have been following this blog you will have no doubt realised that I am very much a fan of the picaxe range of microprocessors. Amongst things that are appealing are low cost, easy to program and the power of them.

Picaxe chips have been finding their way into many projects here including power controllers, temperature controllers and brewing sculptures.

One of the reasons the HERMLET project slowed down dramatically late last year was one of complexity. Once both program code and circuitry get to a certain level of complexity, it is difficult to proceed to design in a reliable fashion.

The free software that comes from Revolution Education to program the picaxe chips has in its latest version had a software simulator built in. This means that code can be stepped through a line at a time by means of debugging - an essential tool.

The latest offering is a commercial package called PicaxeVSM and this offers schematic drawing features with full analog and digital modelling of circuits - integrated with picaxe and code debugger. This means that you can literally step through lines of code and watch virtual LEDs come on when an output turns high (depending on code and circuit). If that isn't good enough on its own, I2C, SPI, RS232 and USB debuggers help you keep track of these many communications features that a picaxe is capable of. And then you can connect two picaxes together (such as I have with the current HERMAN machine) and watch them interact on a PC screen before you build the circuit. And you can even connect to a real PC or picaxe from your virtual circuit!

I am totally sold on what this software can do, and I'm finding it hard to slow down and learn about it properly before I leap into more design and improvements on HERMAN and HERMLET. It has already proven itself to be invaluable - a couple of days ago I was modelling on screen the control panel that HERMAN uses (the array of resistors and push buttons that get decoded as and ADC value) and I accidentally left off a ground connection. In my mind I knew it should work - but when the voltage and ADC values showed me there was a problem, I discovered my mistake. In the past it has been too easy to overlook simple errors only to find them once a board had been built.

For just over $AU 100, this seems to be the bargain of the year.

A few years back when I began to make printed circuit boards for the HERMAN project, an internet search revealed that ExpressPCB had software available for free, which is a good price for any hobbyist.

The string attached to this free offering is that the format of files is their own specific one, and that the software is geared towards internet ordering of boards from them. OK, not a bad thing in itself, and it was the software I began to work with and know how to use quite well.

Since then I have been made aware of other offerings that I probably would have chosen over ExpressPCB, had I known of them at the time.

EAGLE is probably the best known as it has a free offering (full program but limited size board) and is a bit quirky to get up and running. I have just begun to appreciate the power of EAGLE thanks to some terrific tutorials on the instructables website.

The other one that seems to deserve attention is the open source program KiCad. It seems to have a lot in common with EAGLE, and even though it is a free offering, the summer edition of Elektor suggests it is not lightweight in what it can do.

Although I'm most familiar with ExpressPCB, I can't say I'm really happy with it. It is very basic, and it gets the job done, but it doesn't do much to harness the power of the PC. I can't say I'm all that impressed with either EAGLE or KiCad either, but for different reasons. Both these offerings are incredibly powerful and versatile - but they are damn hard to work out how to use.

Having been a bit disillusioned about computer aided software for schematics and PCBs, I happened by chance upon DipTrace. After some serious analysis, I think I have finally found the program I've been looking for.

DipTrace is easy to use. It has a very capable autorouter. It is not too difficult to find components when you need them. It is easy to change the outline of any component for the PCB. It comes with a very capable 250 pin free version. There are not-for-profit entry points, home packages all the way up to professional offerings.

The reason I came upon DipTrace is because I am now a happy owner of PicaxeVSM software.

PicaxeVSM is a spice based virtual modelling program which models the range of picaxe micros and can do analog electronics as well. Schematics seem even easier to draw on PicaxeVSM than DipTrace. Where DipTrace comes into play is for making PCBs.

So after a long break of thinking about other things, I'm set for another round of playing with things electronics and beer.