Using P0.27 as GPIO with nRF9160

[Fabien Comte]

Hello,

I want to use P0.27 as output but no way to get it working (tested on my custom board and on DK). If I just change for another pin to check my code, it's OK.

It looks like if P0.27 is used somewhere else but I Don't know how to get it. 

[Didrik Rokhaug]

Hi.

By default, P0.27 is used as the CTS pin for UART0 on pca10090.

On the DK, that pin is not routed to the header by default.

In this ticket, I explain how to change the pin routing, and provide an application that routes the pins used by UART0 to the headers.

Can you try to flash the application provided there to the nRF52840 board controller on the DK, and see if that helps?

You might also have to assign a different pin to UART0.

Best regards,

Didrik

[Fabien Comte]

Hello Didrik,

But on my custom board, how to disable VCOM to use P0.27 ?

[Didrik Rokhaug]

Have you tried to search through <your build folder>/zephyr/<board_name>.dts_compiled to see if the pin is used for something else?

[Fabien Comte]

Not used in application but bootloader (MCUboot) does. Do my nrf9160_pca10090ns.overlay apply on bootloader ?

[Fabien Comte]

I forced in all files and it works now.

Thank you for your help Didrik.

[Didrik Rokhaug]

No, each image has its own overlay file (application, SPM, MCUBoot).

You can add an overlay file for the bootloader by adding the following to your CMakeLists.txt:

set(mcuboot_DTC_OVERLAY_FILE
  ${CMAKE_CURRENT_SOURCE_DIR}/mcuboot.overlay
  )

If you want to, instead of having multiple overlay files, you can point all images to the same one.

[Fabien Comte]

Hello Didrik, that's perfect.

Thank you.