Custom STM32 Nucleo 64 PCB without CN2

[AnLewis78]

I am in the  process of designing a custom PCB board that uses the CN4 ST-link pins to flash to the processor (rather than the standard USB Micro-B connector). Through testing with a multimeter, I have confirmed that the CN4 line is connected to the processor, and the CN2 jumpers are linked to the embedded st-link processor. Where I am hazy on is how the jumper effects me using the CN4 pins. If I were to not include the embedded st-link and CN2 jumpers (for all I know currently, it is just used to flash other devices), would I still be able to properly flash my STM32L476 processor?

[TDK · Accepted solution]

The CN4 header isn't needed, it is only used to flash external targets. You can leave it off. The CN2 jumpers are also not needed, but if you leave them off you need the schematic to reflect the state with jumpers installed (i.e. connect pins 1+2 and pins 3+4).

The schematics for the nucleo boards are available. That's going to be simpler to go off of than using a multimeter to determine connections.

https://www.st.com/en/evaluation-tools/nucleo-l476rg.html#cad-resources

https://www.st.com/resource/en/schematic_pack/mb1136-default-c05_schematic.pdf