nRF52840 as USB to UART bridge

[Erland]

I am working on a custom board with two MCUs, one nRF52840 and one older MCU.

In the previous iteration of this PCB the old MCU was connected to USB through an FTDI FT232 and flashing was done though USB using the UART bootloader that comes pre-loaded on the old MCU. On the new board the USB is connected directly to the nRF52840, and the lines previously going from the FT232 to the old MCU are now connected to the nRF instead.

So the question is, is it possible to use the nRF as a replacement for the FT232 when I need to flash the old MCU? And if so, is it then also possible to still have the nRF use the USB connector for itself? Ideally I would see two different virtual COM ports show up on the PC, one for the nRF and one for the bridge.

[ovrebekk]

Hi Erland

It is possible to have the nRF52840 enumerate two different com ports if you wish. 

One you can connect to the physical UART interface, to act as a bridge to your second controller, and the second one you can use to access the nRF52840 device itself. 

The USB stack will allow you to assign the 14 bulk/interrupt endpoints freely, and as long as you don't run out of endpoints you can add more USB classes. 

Best regards
Torbjørn

[Erland]

Great! How would I go about assigning endpoints to set this up?

[ovrebekk]

Hi Erland

Sorry for the slow reply, I lost track of this case unfortunately. 

Did you manage to combine the endpoints as you wanted, or do you still need help with this?

Best regards
Torbjørn