Communicate error

(This message was transferred over from our old forum)
Posted August 14, 2015
By Todd DeBoer
[hr]
On 3/16/10 wjt asked, “error message: Unable to communicate: Xmit/Receive

I am having communication problems using USB-ICP-LPC9xx flash programmer for the P89LPC924 parts. I am using the 7.373 mhz internal oscillator. 1st board programmed all the time and 3 other boards give the “can’t communicate” error – no shorts or opens on the boards. Problem is when reading the uP signature. Where to start? It looks like 3 bad uP (unlikely). One board would program intermittently.

Did some more experimenting— cleaned the 2nd board with alcohol changed the Flash Magic oscillator frequency to 14 mHz and read signature as: 00 00 00. Then back to 7.2mHz and it read signature correctly and it programmed. Later it won’t read signature anymore.

Changed uP on 3rd board to P89LPC925 (and Flash Magic). Washed board with alcohol and tried various oscillator frequencies. At times a signature reading would occur and then it started timeout and no communication error would pop up. uP never was programmed.

4th board was programmed once but now won’t even read signature (LPC924). Added 10k pullup on reset pin on uP. Now it rarely goes into the timeout mode but just says it can’t communicate regardless of the Flash Magic oscillator frequency setting. Some LEDs on board indicate the board does reset but then continues to run old program. It should stop running the old program when signature is read.

Using latest Flash Magic software. Can you suggest a solution?

5 programming pins are isolated except 2 LEDs and 0.2uf on VCC. Added 10k pullup on Reset pin on 2 boards.”
[hr]
(Follow up post)

Answered:

It sounds like you might have incorrect timing files for T1 and T2 in Options->Advanced Options->Hardware Config dialog.

The default appears to be 150/150, but it may need to be higher/lower due to hardware configuration. I would recommend going both ways and trying 100/100 and then 300/300 (T1 and T2 respectively). This may just give the lines enough time to properly reset the target into programming mode.