Aconno ACN52840 module does not resetting after programming by J-Link, RTT not working.

[Grzegorz K]

After problems with the programmer I have successfully flashed simple custom board with ACN52840 module, but the unit does not resetting after flashing using J-Link Pro. Starting after grounding reset pin or "nrfjprog --reset".

Terminal show:
Enabling pin reset.
Applying pin reset.

Simple board configuration:

3xVCC shorted

3xGND shorted

470uF capacitor across supply

Reset pulled-up by 10kohm.

Jlink pro connected to SWDIO, SWDCLK, GND, Vcc.

Another maybe related is that there is nothing on RTT viewer, on the nrf52840DK RTT and reset after programing is working as it should.

[Jared]

Hi,

Are you able to do a recover with nRF Command Line tools:

nrfjprog --recover

Is any error returned?

If an error is returned, can you repeat it but with the --log command added:

nrfjprog --recover --log

regards

Jared 

[Grzegorz K]

Hi, recovered successfully without errors but it did not change anything.

Recovering device. This operation might take 30s.
Erasing user code and UICR flash areas.

[Jared]

Hi,

Ok, but are you able to verify whether the device was actually recovered, a recover will erase the flash. Can you also elaborate on whether flashing a sample such as the blinky sample works? Do you see the gpio toggling?

Can you also specify what voltage you measure on:

1. VDD
2. nRESET
3. GND

regards

Jared 

[Grzegorz K]

I was day off the work today, so could not check it, but I presume that it was recovered, than I have flashed it again  with my modified blinky from DevAcademy SDK fundamental course and indeed it is toggling, but after pin reset or nrfjprog --reset or voltage interrupt of course. Nrf52840DK perform as it should flashed with the same  example. VDD as I remember was 3.4 vs. GND, I will check tomorrow what is on nRESET.

I have just recall that I have had same problem with the other project based on nRF51. Programmed the same way (Jlink pro connected to SWDIO, SWDCLK, GND, Vcc), I had to remove battery after flashing to get it work.

[Jared]

Hi,

The nRF52 series usually requires a reset or power cycle after it has been flashed. If the issue is that the reset pin does not start the program after you have flashed new fw to it, and that you have to power cycle it for it start. Then the issue might indeed be related to the RESET line. Can you share the schematics of your custom board?

Can you also verify by measuring directly on the RESET pin that it's pulled low to GND when you do a reset?

regards

Jared