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Re: [avr-gcc-list] avarice and I/O ports during JTAG programming/debuggi
From: |
Theodore A. Roth |
Subject: |
Re: [avr-gcc-list] avarice and I/O ports during JTAG programming/debugging |
Date: |
Tue, 18 Nov 2003 22:48:14 -0800 (PST) |
On Tue, 18 Nov 2003, Brian Cuthie wrote:
>
> Hi All,
>
> I'm seeing some strange behavior from the I/O ports on an ATmega16 while
> doing JTAG debugging and programming using avarice. Specifically, I'm
> seeing a bunch of state changes on I/O lines programmed for output (from
> code already in the avr chip) when avarice reads the configuration and
> fuse bytes. This concerns me a bit, since it can create temporary I/O
> states that may be damaging to hardware interfaced to the processor.
>
> I have two questions:
>
> 1) Is this behavior by design? or is this some issue with avarice?
This may be by design. Doesn't jtag boundary scan let you twiddle pins to
test for opens and shorts?
>
> 2) Would it possible for avarice to reset the processor before doing any
> other JTAG operations so that the I/O ports are forced to be dormant?
That depends are what jtag ops you are talking about. In most cases, I don't
think it would hurt to reset the device. The only cases I can think of where
you wouldn't want to reset is when you are using the --capture option. Nils
just did a bunch of work on that last week
It should just take call resetProgram() at the right place. Have a look in
main.cc and see what you come up with.
Ted Roth