Flashing dual MCU (nRF54 and nRF91)

[JackT]

Hello everyone!

I have a question about flashing firmware to a PCBA with the nRF54 and nRF91, or any dual MCU board in general.

When looking at the Thingy91(x) this has a physical switch to mux the output of the SWD to either of the chips.

This method works fine when developing and testing, but how should this be approached during production?

Should there be 2 SWD connectors?

Have the first chip be connected to the mux, and when it is flashed and powers on it pulls up/down so the other chip is selected?

What is the best approach for this?

Kind regards,

Jack

[rajeev]

 JackTusing 2 separate SWD connectors will simplify your life, as you will not need to use any muxes or manage them. One can flash the devices independently without issues.

But if its a space constraint, then using a mux might be the way, but then you will need to make sure it's muxe'd properly else one will not be able to program the chipsets.