On Mon, Feb 06, 2006 at 08:44:02AM -0800, Bob Blick wrote:
> Byron A Jeff wrote:
> 
> > BTW I think that USB to serial is a better investment.
> 
> It's not just a better investment, it's an absolutely neccessary one. If
> you do any tech at all, you need a serial port.

Bob, you of course know you're preaching to the choir with me.

> I've done PIC development three different ways:
> 
> 1. True hardware emulator
> 
> 2. ICD/ICD2
> 
> 3. Serial bootloader
> 
> #1 and #2 suffer from power cycling issues. Unless your circuit draws very
> little current, you end up haveing to mouseclick and flip switch in just
> the right order or everything hangs.
> 
> #1 is very expensive.
> 
> #1 is very noisy if you are doing analog stuff.
> 
> #2 uses pins you really want to use for other things.

This is one of the primary reasons I like bootloaders.

> #2 gives you very little in the way of debugging.

Can you expand upon that? It would seem that hardware breakpoints
would be the ultimate in debugging capability.

> #1 and #2 are most useful when you can single step. Not useful at all in a
> realtime circuit, especially one that can self-destruct if stopped at the
> wrong time.
> 
> #3 uses just one cable, no extra power, is fast, and you can debug through
> it. Sure you have to include a serial output routine in your code to do
> it, but it doesn't take much to set up the usart and output a byte where
> you'd put a breakpoint.

usart? I have bit bang serial routines for output. Usually I use Timer2 because
of it's autoreload feature.

> So in the future, you'll have a serial port or it'll be on your list
> anyway. Getting a bootloader into the PIC is the important thing. Byron's
> circuit with 555's is a step in the right direction. You can still get
> them at Radio Shack! And the circuit could also be built with schmitt
> triggers or oneshots if you prefer.

Glad to get some support in this matter. 

Thanks,

BAJ
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