Pi in the sky

[Mark Hennessy]

A basic explanation of what they are and what you can do with them would be a good start. From the negligible amount I know they seem to expensive and complicated for the sort of things I do but I'm ready to learn otherwise.

You could do worse than start at my site: http://www.mhennessy.f9.co.uk/pic/index.htm

For example of projects that use them, have a look at these:

http://www.mhennessy.f9.co.uk/preamp/index.htm
http://www.mhennessy2.f9.co.uk/a4/index.htm

In terms of when to use them, if you're designing a logic circuit with more than half a dozen chips, then it's worth considering a micro-controller, or perhaps a programmable logic array. For an example of something that falls into this category, have a look here:

http://www.mhennessy1.f9.co.uk/nicam/index.htm

The logic board (bottom left) uses 2 big special ICs and a whole load of CMOS logic. Everything on that board would fit into a single PIC. Not that I was able to use PICs back in 1991 - indeed, back then, PICs didn't come with flash memory, so you needed rather more expensive hardware to use them...

Regarding cost, PICs are pretty cheap. Comfortably less than £5 for a basic chip - more like half that really. Microchip do offer samples, though sample requests tend to vary in their success. I could send you a couple if you like. Next, you'll need to build a programmer to connect to the serial port of your Win98 machine, then you'll need to install some free software.

The final point you make is complexity, and yes, depending on what you'd like to achieve, a PIC might be overkill. You wouldn't use a PIC to make a light flash, although making a light flash might be your first "hello, World" programme. You might use one to make a single-chip tape counter IC:

http://www.vintage-radio.net/forum/showt...hp?t=73694

The best way to learn anything - well, for me at least - is to have a project. When I did that hi-fi preamp, I knew that I wanted to decode an IR remote, I knew that I wanted to use a display of some sort, and I knew that I'd be controlling relays and a volume control. All of that might have been possible using conventional logic, especially as there used to be a nice Philips IC that decoded the IR. That IC went obsolete just as I was getting my act together, so that forced me down the micro-controller route. Later, as I made final decisions about how I was going to control the volume, I decided on those PGA2310 ICs, but these needed a simple serial control signal - which turned out to be very easy to code on a PIC. That's just one example, but the further I got into the design, the more glad I was that I'd chosen to use a PIC.

Basically, if you're even half-interested, give it a go!

All the best,

Mark