I have built a HV programmer for AVR but I have never have the need to use it for several years. The programmer is gathering dust.

Now you are familiar with AVR, why not take sometimes to play around with PIC too? It is also great fun when tools like "programmer+debugger" PICKIT2 is available from Microchip and is not that expensive.

For UK hobbyists, the PICKIT2 is a bargain if you bought the EPE magazine and get the deal from Microchip Direct. The offer doesn't end till January next year so hurry up.

If you're doing high speed or time critical I/O handling an AVR is 4 times faster than a pic on carefully written code, this is mostly noticed by ASM programmers as you have very tight control over code timing in ASM. AVR's are much friendlier for ASM programmers do to the large register file, and offer speed boost to do significantly decreased paging when using C code compared to a PIC. By large and far I have to agree with Harvey, I spent several months researching PICs/AVRs and other architectures and found AVR the hands down winner for me. I haven't seen an AVR PDF that has it listed and I think the major advantage PICs have is their timers can be clocked asynchronously. I think all AVRs are bound to the sampling of the system clock, so PICs definitly have the hand up in situations like frequency counters.

Originally Posted by Sceadwian

I haven't seen an AVR PDF that has it listed and I think the major advantage PICs have is their timers can be clocked asynchronously. I think all AVRs are bound to the sampling of the system clock, so PICs definitly have the hand up in situations like frequency counters.

Neither is synchronous. They both will run from external clocks and both are synchronized to the internal clock. "So PICs definately have" no hand up and you are left with performance and power characteristics to decide on.

If someone told you that AVR timers could not respond to external signals they were lying. You are quite right, counters border on useless if they can not respond to the outside world-and the silicon designers know it!

Are you sure? Nigel mentioned this a ways back and I checked the PDF for the PIC he was talking about and it specifically stated the timer was asynchronously clockable. I can't remember the model of the pic though. I thought it was neat because the PDF stated the timer was rated for 50mhz even on a much slower part clock so they were good for frequency counters. You could only sample the timer on a system clock boundry but the timer itself ran asynch, perfect for frequency counters.

There was a 50MHz counter in the MicroChip application notes years and years ago, so long ago it used an OTP chip - many years later it was ported to the EEPROM based chips (and LCD replaced the LED display), and for many years was available as a kit (I have one here I bought a long time back).

Uber you seem to be confused. AVR or PIC you can only sample the externally driven timer during a system clock boundary. But on a PIC the timer itself is asynchronous. It's limited only by it's analog bandwidth and the driven signal, which can be WAY past system clock speeds. The AVRs externally driven timer is synchronized to the system clock, Nyquist kicks in real fast, if you try to sample a signal more than 1/4 the system clock of an AVR you're going to get aliasing effects that will mirror harmonic frequencies.
Either way really if you want a truly high speed frequency counter with PIC or PIC you just use an AVR or a PIC and you pick a good external counter and just use the PIC or AVR to sample it, they're both limited on sampling to system clock ticks anyways, and you can get massively higher frequencies with an external counter.

Originally Posted by Sceadwian

Either way really if you want a truly high speed frequency counter with PIC or PIC you just use an AVR or a PIC and you pick a good external counter and just use the PIC or AVR to sample it, they're both limited on sampling to system clock ticks anyways, and you can get massively higher frequencies with an external counter.

I'm a little confused what you're on about?, all you need for massive higher frequencies is a prescaler - which you require anyway, for frequencies higher than 50MHz or so (usual TTL upper limit).

Originally Posted by Ubergeek63

Who uses those museum pieces anymore? LV uses a fraction of the power and runs 200MHz for around not much more money.

You still need a prescaler to get to 500MHz, so there doesn't seem much advantage? - 500MHz is a commonly desired range to cover both 2m and 70cm.