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CrossConnect / J-Link Differences?

Started by Simon Ansley January 9, 2007
Hello,

I have a system using LPC2214 which has been working for around a
year now. Recently I made some mods to the PCB (basically a change
from predominantly Through Hole to SMT). Along the way the reset
circuit got changed from passive R-C (56K Pullup) to active (LM3724
with 10K Pullup), and to save on assembly machine feeders the pullups
on the JTAG were changed from 47K to 10K.

I received the new board today, and after checking PSUs etc got the
board talking fine with FlashMagic.

I then tried to connect to JTAG, using my usual IAR (Segger) J Link
and Rowley Crossworks. I continually got failures during the Erase
stage, citing TAP errors, and could not download code. I tried
slowing the clocking right down, but same problem. All the signals
beep through fine and look nice and clean on the 'scope, but still no
download. I could, however, attach to and debug running code
downloaded through Flash Magic.

I then tried our other adapter, a Rowley CrossLink. This worked fine
first time!

It's obviously not a show-stopper as I can work with the CrossLink,
but I'm curious to what is happening here. The J-Link still works
fine with the previous version of the board. Can anybody shed any
light?
Thanks

Simon Ansley
www.spidevelopments.com

An Engineer's Guide to the LPC2100 Series

On Tue, 09 Jan 2007 17:23:12 -0000, you wrote:

>Hello,
>
>I have a system using LPC2214 which has been working for around a
>year now. Recently I made some mods to the PCB (basically a change
>from predominantly Through Hole to SMT). Along the way the reset
>circuit got changed from passive R-C (56K Pullup) to active (LM3724
>with 10K Pullup), and to save on assembly machine feeders the pullups
>on the JTAG were changed from 47K to 10K.

Looking at the NS data sheet, the LM3724 has push-pull output - Is there a series R from the LM3724
to Reset ? If not, the J-link's reset driver will be fighting the LM3724.
--- In l..., Mike Harrison wrote:
>
> On Tue, 09 Jan 2007 17:23:12 -0000, you wrote:
>
> >Hello,
> >
> >I have a system using LPC2214 which has been working for around a
> >year now. Recently I made some mods to the PCB (basically a change
> >from predominantly Through Hole to SMT). Along the way the reset
> >circuit got changed from passive R-C (56K Pullup) to active
(LM3724
> >with 10K Pullup), and to save on assembly machine feeders the
pullups
> >on the JTAG were changed from 47K to 10K.
>
> Looking at the NS data sheet, the LM3724 has push-pull output - Is
there a series R from the LM3724
> to Reset ? If not, the J-link's reset driver will be fighting the
LM3724.
>

Are you sure? The data sheet at
http://cache.national.com/ds/LM/LM3722.pdf shows LM3272 and LM3273 as
push-pull and LM3274 as open drain. Presumably if this were the
problem the CrossConnect wouldn't work?

Thanks,

Simon