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?

On Fri, 1 Nov 2013 21:50:44 +0800, "Bruce Varley" <bv@NoSpam.com>
wrote:

>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?

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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"Bruce Varley" <bv@NoSpam.com> wrote in message 
news:QOOdnWi_dq14LO7PnZ2dnUVZ7tednZ2d@westnet.com.au...
>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?
>
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.

 

On Mon, 4 Nov 2013 21:48:27 +0800, "Bruce Varley" <bv@NoSpam.com>
wrote:

>
>"Bruce Varley" <bv@NoSpam.com> wrote in message 
>news:QOOdnWi_dq14LO7PnZ2dnUVZ7tednZ2d@westnet.com.au...
>>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?
>>
>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.

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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