CONFIG_ASSERT makes the UART driver assert when using no flow control i.e. using 0xFFFFFFFF for rts/cts

Question

Ways to reproduce:

Create SES project with the following:
nRF Connect SDK: v1.5.0
Project: blinky
Board name: nrf52833dk_nrf52833 (can probably be any nrf52xxx). Also happens for nRF52840-DK at least.

Modify dts file or add overlay to use the following UART config:
&uart0 {
compatible = "nordic,nrf-uart";
status = "okay";
current-speed = <115200>;
tx-pin = <6>;
rx-pin = <8>;
rts-pin = <0xFFFFFFFF>;
cts-pin = <0xFFFFFFFF>;
};

We used the following prj.conf:
CONFIG_GPIO=y
CONFIG_ASSERT=y
CONFIG_DEBUG=y
CONFIG_UART_INTERRUPT_DRIVEN=y

It's asserting in nrf_gpio.h line 538.

Sigurd · Accepted Answer

Hi,

I think this way to disable flow control was changed in a recent Zephyr verison.

Try using /delete-property/ instead. Snippet:

&uart0 {
compatible = "nordic,nrf-uart";
status = "okay";
current-speed = <115200>;
tx-pin = <6>;
rx-pin = <8>;
/delete-property/ rts-pin;
/delete-property/ cts-pin;
};

CONFIG_ASSERT makes the UART driver assert when using no flow control i.e. using 0xFFFFFFFF for rts/cts

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