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Startup problems, Olimex LPC-L2294

I have a straight out of the box Olimex Arm-7 board, plugged into a just purchased Segger J-link JTAG adaptor. On powering up, the host software can't detect the target, the LED on the JTAG modules is orange. I posted this on the Segger forum, and the advice was that the Olimex board was in reset. I then posted this back on the Olimex forum and have not received any responses in a week. Is anyone using this board, and can tell me what might cause this problem? Is there something else that needs to be done following powerup to get the connection working?

As an aside, the amount of documentation available from Olimex on this board seems absolutely minimal - all I can find is a PDF file with a board layout and a schematic. No how to get started documentation whatsoever. The wiki is completely unpopulated. Is anyone aware of a source of information that might help get me up and away?

Reply to
Bruce Varley
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Check the other LPC-2294 Olimex boards for some (small) additional info, even though there will be differences. The lowest level, boot elements should be virtually identical.

There is an "lpc2000" group over at Yahoo that is pretty active. Lots of messages returned to a search on "2294" so that may be one resource. Otherwise, dig into the data sheet and user manual for the details on how the option pins need to be configured for the desired boot and JTAG operation.

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Reply to
Rich Webb

Power supply, but not in the way you might expect. The only information on the supply specs seems to be on the website schematic, it states 6Vdc or

4.5Vac. The power input to the board goes through a bridge and an electro so that seemed OK. But the DSO showed that the level of ripple on all the rails was huge with AC supply. Replaced with solid 6Vdc and everything was OK.

Mains here is 50 Hz, but if it doesn't work on 50Hz it's still going to be damn marginal on 60. Might this arrangement be targetted at 400 Hz supplies, aircraft etc? Is the bridge/cap arrangement on SBCs widely used or might this just be a (slightly) weird design.

Reply to
Bruce Varley

Ah, good catch. It looks like it's a cut'n'paste of their standard setup, which is evidently under-spec'd for a board as populated as that one is. With a 4.5VAC input it would only be able to source a few mA before falling below the dropout limit on the 3.3V regulator between cycles. I generally drive these from a benchtop DC supply, easier than rummaging around for a matching wall wart, but you could probably get it going okay with a larger AC input voltage.

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Reply to
Rich Webb

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