Segger J-link fails to reset nrf52840 rev C

RE: Segger J-link fails to reset nrf52840 rev C

Håkon Alseth — Tue, 19 Jun 2018 13:05:31 GMT

How do you handle the DW1000 RSTn pin? The DW1000 datasheet has its own chapter on handling this signal, so it seems that bad behavior can occur if it's sourced externally. The nRF GPIO controlling this signal should be configured with PIN_CNF[n], field DRIVE = S0D1 (or H0D1) to avoid this scenario.

Best regards,

Håkon

RE: Segger J-link fails to reset nrf52840 rev C

Mike — Mon, 18 Jun 2018 21:37:20 GMT

The DW1000 reset sequence is to pull the RSTn line low for 500us, then wait for the STATUS.CPLOCK bit to be set to 1. It's that waiting for the bit to be set to 1 is where we have a 75% chance of hanging forever.

The same code doing the same reset procedure works 100% of the time on a Rev. B '840 board and the '832 in Decawave's DWM1001 module.

The fact that the DW1000 does successfully reset ~25% of the time makes me believe that something on the Rev C board is marginal. The question is what is marginal? A chip? A pullup? A route? A placed component? ...

Back to looking at the Gerbers.

RE: Segger J-link fails to reset nrf52840 rev C

Håkon Alseth — Mon, 18 Jun 2018 07:06:41 GMT

Unfortunately, I do not have any experience with the DW1000 IC, but this sounds like an initialization issue. Reprogramming and resetting the nRF will not automatically reset the DW1000, unless you actively do so as a part of the nRF startup routine. Could the DW1000 be in a state where it is awaiting specific commands from the nRF?

Best regards,

Håkon

RE: Segger J-link fails to reset nrf52840 rev C

Mike — Fri, 15 Jun 2018 14:31:04 GMT

Sorry, I typed the nrfjprog command incorrectly into the message above. The '--erase' option should have been '--reset' so the whole command I flash the device with is:

nrfjprog --program nuttx.hex --sectorerase --reset

and just plain

nrfjprog --reset

will also cause the '840 to wait forever for the DW1000 to synchronize its clock. Both GDB and the output of our code confirm that the '840 is running, reading the status bit from the DW1000, and looping over and over.

There's some kind of weird coupling between the '840 being reset by the J-Link and the DW1000 not coming out of reset correctly.

RE: Segger J-link fails to reset nrf52840 rev C

Håkon Alseth — Fri, 15 Jun 2018 07:33:02 GMT

Hi,

When programming using nrfjprog, it leaves the nRF in a halted state unless you do a "nrfjprog --run" or a "nrfjprog --reset" afterwards. Could this be the issue?

Cheers,

Håkon