Q1) Do you have any other 20732S boards that have the problem of continually resetting?
Q2) On the board that is un-responsive, can you put an O-Scope on the UART_TX pin to capture what the 20732S is trying to "say" during programming?
Stated differently. During the download of the new image via the SDK, there is a communications protocol back and forth. You will be able to see where the host wiggles the UART_RX pin when talking to the 20732S at the beginning of the program session.... I want to see if the 20732S is responding in any way on the UART_TX line.
A1) My other 20732S boards do not have this problem.
A2) THe board now seems to be 'dead' (traces don't show up anymore, the reset LEDs don't flash like before, reset pin does not elicit a response, SDK does not recognize the device). It is only if I unplug and re-plug in the battery will then the module be recognized and try to download (but still fail).
When I probe it, I get something like this before the download fails....
Nice picture and helpful.
Please change your sweep-time from 5mS to 10uS and give me a couple more "close-ups".
The UART pin is a digital I/O and should get driven fully high/low. I am looking for instances where pulses aren't driven fully high, or have really long rise times when going from low to high, or vice-versa. Kind of like what you show at the start of the 3rd division (past the center-line) on your capture.
Within Appendix E of the Quick Start Guide, there is a procedure for "Recovering A Corrupted WICED Smart Tag"
You may want to try this as well.
Are you still struggling with these boot issues?
Please let us know.
JT - the problem (corrputed waveform on UART_TX) reported in this issue by mochi are eerily similar to the problems reported over here BCM20732S based boards sometimes develop UART failure by ldgirod.
I couldn't resolve this issue, so I moved onto another dev. board we had.
1. Do you have the lot-code of the module on the failing board?
2. Were you using an FTDI cable / device during programming or some other (USB<->UART) mechanism? What voltage cable?
3. Am I reading the waveform correctly? The signals show ~5volt rail whereas the device is only rated at 3.3 volts.