nRF5340, switch UART code to use another peripheral (uart1 instead of uart0)

RE: nRF5340, switch UART code to use another peripheral (uart1 instead of uart0)

afok-esmart — Thu, 29 Feb 2024 22:53:24 GMT

I also did get it working for my dual-core project as well; I ended using UART1 (with different pins) for the #1 code and UART0 (default i.e., no pins were changed) for the #2 code. In my case, I didn't need UART1 to output to the VCOM and chose P0.25 and P0.26. In short, these were the additional code changes I needed to make:

nrf.overlay, add '&pinctrl' block with my own default/sleep configurations (but w/ P0.25 and P0.26)
- My default & sleep configurations had label 'uart1_alt_default' and 'uart1_alt_sleep' respectively
- Configurations had same format as ones like 'uart0_default' and 'uart0_sleep' (see NCS 2.5.0 at zephyr/boards/arm/nrf5340dk_nrf5340/nrf5340_cpuapp_common-pinctrl.dtsi)
nrf.overlay, edit '&uart1' block to additionally have:
- pinctrl-0=< &uart1_alt_default >
- pinctrl-1=< &uart1_alt_sleep >

RE: nRF5340, switch UART code to use another peripheral (uart1 instead of uart0)

afok-esmart — Thu, 29 Feb 2024 22:51:47 GMT

Yes that seemed to be it; the net core was indeed 'getting in the way' (thanks Hieu). If I made my changes to #1 (see original post), but in another project that didn't utilize the network core, they worked. In hindsight, I probably should have tried this first. But glad to know my changes to #1 are at least one way to change from uart0 to uart1.

RE: nRF5340, switch UART code to use another peripheral (uart1 instead of uart0)

Hieu — Wed, 28 Feb 2024 21:07:38 GMT

Hi afok-esmart,

By default, the 2nd UART interface with P1.00 and P1.01 are given to the network core UART. That's likely why you are not getting the application core UART1 output, whose default pins are the same.

Do you need UART1 to output to the virtual COM port? If not, the simplest way is to just change the pins to another unused pin. You can use the Devicetree Visual Editor to help you pick something not yet occupied.

If you do need the output to go to virtual COM too, you have a few options.

Only possible on nRF5340DK v1.0.0) Wire the changed pins to the UART interface available on P24 on the DK.
Give the network core some other pins to use.
1. Overlay the gpio_fwd node with other pins for the network core.
2. If you are building the network core as a child image, add an overlay to the child_image folder to change the network core's default UART pins to the new pins.
Disable network core UART altogether.
1. Disable the gpio_fwd node in overlay by setting status to "disabled"
2. If you are building the network core as a child image, add an overlay to the child_image folder to disable the network core UART node.

Hieu