NRF52 locked, can't recover

RE: NRF52 locked, can't recover

AmbystomaLabs — Thu, 18 Jan 2018 20:42:32 GMT

I'm glad you were able to recover the boards. It is not uncommon for designers to not bring out reset, though I can't say I have ever done that.

All the ARM SWD comms are the same. Here is a blog entry from someone with an ST processor and the same problem: electronics.stackexchange.com/.../stm32-st-link-cannot-connect-to-mcu-after-successful-programming

RE: NRF52 locked, can't recover

brett_anderson — Thu, 18 Jan 2018 19:40:15 GMT

I can't. The hardware designer did not include a reset line in the design. I did find out that if I let the batteries die, I am now able to reprogram them. I'm taking that as circumstantial evidence that you are correct.

RE: NRF52 locked, can't recover

AmbystomaLabs — Thu, 18 Jan 2018 19:32:20 GMT

Ok. Please comment back on whether asserting reset during SWD fixes your dead boards.

RE: NRF52 locked, can't recover

brett_anderson — Thu, 18 Jan 2018 17:50:00 GMT

The warming up is because of the design. The boards regulate power, and if they lockup in the wrong state, the power is no longer controlled. That is not related to the other problem, and I should not have included it looking back.

RE: NRF52 locked, can't recover

AmbystomaLabs — Thu, 18 Jan 2018 17:38:57 GMT

In one of the nRFgo Studio docs, I remember it mentioning something about the processor ignoring the SWD commands under certain circumstances. I think it said the solution is to make sure reset is connected.

I searched around for ARM related SWD problems and found similar problems/solutions. According to the entries the SWD can be ignored due to faulty firmware. The solution was always assert reset so that the erase command can be issue via SWD.

Though, the warming up part of your processor problem sounds odd. Could just be really screwed up firmware and something is going wrong on the main clock. A reset assert should still fix it.

RE: NRF52 locked, can't recover

brett_anderson — Thu, 18 Jan 2018 15:53:21 GMT

I grabbed a new device that wasn't locked.

RE: NRF52 locked, can't recover

Hung Bui — Thu, 18 Jan 2018 15:47:54 GMT

It's still not very clear to me how you recovered the chip and flashed new firmware ?

RE: NRF52 locked, can't recover

brett_anderson — Thu, 18 Jan 2018 14:46:19 GMT

I'm using a J-Link Ultra+. Voltage is good. I have a bunch of these devices. It seems to be a problem with Keil. I was using the bootloader example from sdk 12.2. I started the project over and it works again.

The big question is what happened in the compiled hex file that was somehow blocking the mcu from recovery?

I am back working with the new project, but if anyone else runs into this it would be nice to know what happened.

RE: NRF52 locked, can't recover

Hung Bui — Thu, 18 Jan 2018 14:26:50 GMT

Which programmer did you use ? Do you have 3.3V VDD with the battery ? Have you tried to use Jlink Commander ? Maybe the answer from RK here can help ?

RE: NRF52 locked, can't recover

Matt — Thu, 18 Jan 2018 03:36:20 GMT

Confused: with nRFgo Studio or nrfjprog you need to have the corresponding JLink connected to nRF52 board and yet you are saying they are sealed units and can no longer connect to them. So do you have a board, with JLink connected, and still cannot recover/reset it?