How to use a black magic probe on a nrf5340 DK

[alexxedo]

Hello all

I have a nrf5340 DK and a BMP firmware flashed on a bluepill.
I would like to use the blue pill to debug the board instead of the embedded jlink (for test purpose).

I know that the BMP does not support officially the nrf53 however I thought I could at least enumerate the chip.

In my attempt I connected the SWDCLK, SWIO and GND pins from the DK board to the bluepill. I connected the nrf USB (J3) connector to a power supply. I also set the power supply switch (SW9) to "USB". As I suspected the embedded jlink to take over the SWD lines, I also set the operating mode to nrf_ONLY through the switch SW6.

After doing that I tried a swdp scan on the bluepill but nothing is listed. I double checked with different wires, pc and bluepill.

The DK in MCU mode with the embedded Jlink works correctly. 

Anybody has an idea of what I am missing here?

Thanks for the answer.

[Kazi Afroza Sultana]

Hello,

The Debug in connector (P18) makes it possible to connect external debuggers for debugging when the interface MCU USB cable is not connected, or the Development Kit (DK) is in nRF only mode.

You should connect the bluepill with P18 pin of the nRF5340 DK. The voltage supported by external debugging/programming is VDD voltage. Normally, this is 3 V when running from USB. But if the onboard nRF5340 SoC is supplied from either USB or lithium-ion (Li-ion) and the nRF power source switch (SW9) is in either Li-Po or USB position, then the VDD can be set by the nRF5340 firmware. Make sure the voltage level of the external board matches the VDD of the nRF5340 DK. 

Thanks.