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Re: [avr-chat] Mega128/jtagice problem.


From: Russell Shaw
Subject: Re: [avr-chat] Mega128/jtagice problem.
Date: Sat, 23 Jul 2005 15:16:19 +1000
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.8) Gecko/20050513 Debian/1.7.8-1

Andy Warner wrote:
I have a project based on the mega128, and I'm having strange
problems when I use the jtag port for programming. The summary is that
it doesn't seem to come out of reset correctly after programming,
but the part is programmed correctly and if I then manually cause
a reset or power cycle the board it behaves correctly.

If I program via the ISP port, it works correctly also.

I'd first check the oscillator starts ok, if it is ever stopped,
by using a *low capacitance* cro probe on the crystal.

Then check that there's no capacitive loads on the jtag avr pins.

If the jtag is powered from the pcb suppy, checks it's not marginal
like < 4.5V.

90% is hardware problems.

If you have long serial cables or go thru a switch-box to the
mk-I, try a much slower baud rate, as it has no error checking.




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