Issues with flashing code on MDBT53V mounted on cusotm board

[Marosh]

Hi,
I am having troubles with flashing my first code to the MDBT53V module. I am flashing via JTAG cable, from my nrf52840DK using vscode. According to my measurements the onboard power sourced by npm1300 on my custom pcb is correct. I can also confirm that the MDBT53V VDD pins are properly receiving 1.8V from the npm1300 VOUT1. On jtag footprint, i can also confirm the GND, 1.8V supply is okay. When jtag is not connected there is 1.8V on RESET pin. When i connect the jtag between custom board and nrf52840DK module i measure 2.2V on RESET pin 3 on JTAG footprint of my custom board for some reason. Both SB47 and SB19 is unshorted on the nrf52840DK, according to how I have understood this guide: https://docs.nordicsemi.com/bundle/ug_nrf52840_dk/page/UG/dk/ext_programming_support_P19.html# On the nrf52840DK I have SW9 switch set on VDD, SW 10 on OFF, SW8 ON.  



This is my footprint on pcb:


I have also tried to short the SB19 and supply 1,8V on the VIO REF of nrf52840 from external source and it gave me slightly different error:


I would appreciate any type of insight into my problem.
Thank you in advance.

[JONATHAN LL]

What version of the nRF52840DK do you have? If it is an older version the debugger on the DK is not able to program the nRF5340 on the MDBT53V module. 



Here is an example on how to connect a external device for programming not unsing the 10pin connector. 

if you are running things of different voltages this might be the issue. Its ok to use the VTG to detect voltage from P20, so you can use P19 together with a jumper for VTG.


Also we can help with schematic and layout reviews if you want to have your design checked. 


Also you can try and run a "nrfutil device info" command or "nrfutil device recover" if the approtection is on in the terminal instead of having to run the flash script every time.  


Regards,
Jonathan