Lpc2000

I have been evaluating the LPC2138 for a few months now using the 
Keil MCB2130 board, Arm compiler, and Arm Multi-Ice emulator. All 
peripherals have been evaluated and the only remaining task was to 
verify the 50uA sleep current. The LPC2138 part on my Keil board was 
a pre-production part with a sleep current of 150uA.

So, I got production samples of the LPC2138 and and had one placed 
on the evaluation board. Everything flashed ok, but I noticed the 
UART did not behave properly. I evaluated the UART using the Modbus 
RTU protocol. It seems to receive packets ok, but the response is 
always garbage. However, if I perform a hard reset after powerup 
using the reset button on the evaluation board, everything works 
fine.

I have no idea what is wrong. I do know the previous part worked 
fine, and this part works fine only after a hard reset. Switching 
the power supply off then on does not work. It seems I have to power 
the board, then do a reset. Go figure.

Hi,

  Maybe the DTR control line for the reset may not be long enough for
the production version of the LPC. The schematics for the Keil unit
showed that the reset had a 10K (and diode in parallel) with 100nF cap
to ground for the reset. From my discussions with Philips about the
reset, they suggested only a 10K resistor or nothing at all.

  Another question. How did you find what parts where production over
pre-production? I have a few of the chips and would like to remove the
pre-production versions from the stock. There was a notice from
Philips about it, but it seems I can not find that note now.

Thanks,
Charles

--- In lpc2000@yahoogroups.com, "tah2k" <tah2k@y...> wrote:

> 
> I have been evaluating the LPC2138 for a few months now using the 
> Keil MCB2130 board, Arm compiler, and Arm Multi-Ice emulator. All 
> peripherals have been evaluated and the only remaining task was to 
> verify the 50uA sleep current. The LPC2138 part on my Keil board was 
> a pre-production part with a sleep current of 150uA.
> 
> So, I got production samples of the LPC2138 and and had one placed 
> on the evaluation board. Everything flashed ok, but I noticed the 
> UART did not behave properly. I evaluated the UART using the Modbus 
> RTU protocol. It seems to receive packets ok, but the response is 
> always garbage. However, if I perform a hard reset after powerup 
> using the reset button on the evaluation board, everything works 
> fine.
> 
> I have no idea what is wrong. I do know the previous part worked 
> fine, and this part works fine only after a hard reset. Switching 
> the power supply off then on does not work. It seems I have to power 
> the board, then do a reset. Go figure.