>
>I have a little setup like this and it's great.
>Flip one switch, program, flip it back, device
>is running. Who needs an ICE?? ;o)
>-Roman

I'm doing an AVR project right now, where one AVR reprograms three other
AVRs in circuit, while not letting the peripherals nuke themselves during
that process.   Each AVR, except for the battery charger, has Jtag ICE
ability.  There's also a PIC, but it's running canned firmware, doing IRDA
to serial conversion.   The AVRs all chat over the SPI bus, with a
busreq/busack protocol.

One of them (tiny-15) is a battery charger, doing PWM to regulate the
battery current with one of the lines that is used for programming, and an
analog reference voltage on another programming line (it's an 8 pin part)
so I used a 4066 to gate the signals, with the 4066 toggled on /RESET
I put a further lockout on the PWM output with a transistor, so that if
/RESET is true, then the output FET is disconnected from the CPU, and
biased off.  It would have been bad, to have the battery get a charge
determined by the programming cycle!  :)

Whenever you're going to hold the processor in reset, and have the rest of
the system powered up, you need to pay close attention to what all those
I/O pins are going to do when the processor tri-states them.

A partner of mine once made the mistake of using an ICE in developing an
impact printer.
Not that this is such a bad idea, except that you don't want to place a
breakpoint anywhere when the hammer drivers might be in the "on"
state...  SSSSSmokin!

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