Programming external nRF5340 MCU with nRF5340 DK

[mm784]

Hello,

I have the nRF5340 DK and I want to program/debug an external SoC. I see that in order to do that I can use the connector P19 to connect to an external board with nRF5340 SoC. Is it enough to connect VDD, GND, SWDCLK, SWDIO and RESET? Must SWO and SEL be connected as well? If so, what is their purpose?

 

Thank you

[MJJ]

Have a look at (+) Programming Custom nRF5340 Board Using nRF5340 Development Kit - Nordic Q&A - Nordic DevZone - Nordic DevZone (nordicsemi.com) and post follow-up questions here.

[mm784]

Thank you 

I also want to clarify something because there seems to be a lot of conflicting information on Dev Zone, and the nRF5340 DK documentation doesn't specify the following:

Can the DK be used to program external boards with VDD other than 3.0V? I understand that 3V is the default when DK is powered by USB, but the VDD of my external boards is not 3V.

Some mention that it is not possible without the use of level shifters
 Programming using P19 external nrf5340 board powered at 1.8V 

Others say it is possible. To do that, the solder bridge SB19 on the nRF5340 DK must be shorted, so that the VDD of the external board is used as VIO_REF for debugging. 

  nRF5340-DK custom board flashing 1.8V 

 I can't program external board with nRF5340 2.0.2 

The board I have with nRF5340 SoC is battery powered and can have a VDD ranging from 3V to 1.8V. 

Can I short SB19 on the nRF5340 DK and have my external board supply VIO_REF to P19 for debugging?