JTAG communication failure, check connection, JTAG interface, target power etc.

Werner Almesberger werner at openmoko.org
Wed Jan 7 17:33:55 CET 2009

Shakthi Kannan wrote:
> I am trying to connect the debug board v3 with FreeRunner to a Debian
> system (running 2.6.26-1-686), and I am getting the following errors:

The FPC connection can be very deceptive. I don't know how many days
(those minutes add up ...) I've already spent trying to figure out
why an apparently perfectly good debug board setup would all of a
sudden fail.

Problems often only seem to show with JTAG because any trouble with
the serial console is usually quickly detected and it's only two
signals anyway, while JTAG is less transparent and it's a whole six
signals that need to work, not just two.

So I would always suspect the cable and the connection at either end,
even if visual inspection suggests that they are good. The cable
itself can also break, although this is a less frequent issue.

- Werner

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