I'm setting up a board I just built in NCS, and I made an overlay file for it. Specifically, I am setting up the UART21 peripheral and assigning pin outputs. I made a mistake of assigning the wrong pins for UART21 (P2.08 and P2.09 rather than P2.07 and P2.08).
I thought to just try out my pin configuration in the overlay file, and see if it'll work. NCS builds it, flashes it, and the code runs. But there is no indication that anything is wrong besides the UART output not actually going anywhere. As in, there isn't a compile time error, nor a run-time error. Is this expected?
Also, why is there a PSEL register at all if there is only 1 valid value for the pin?
DevZone AI response follow up: The AI suggested that I can set UARTE21 pins to any pins within P1. I tried this but none of them actually output any serial data like I got on P2.08. II also tried setting UARTE21.TXD to P2.02 as that's on the datasheet dedicated function list, but that doesn't work.
Here is the overlay file:
/ {
aliases {
ledonboard = &led_debug_0;
};
leds {
compatible = "gpio-leds";
led_debug_0: led_0 {
gpios = <&gpio2 6 GPIO_ACTIVE_HIGH>;
};
};
};
&pinctrl {
uart21_default: uart21_default {
group1 {
psels = <NRF_PSEL(UART_TX, 2, 2)>;
};
group2 {
psels = <NRF_PSEL(UART_RX, 2, 0)>;
bias-pull-up;
};
};
uart21_sleep: uart21_sleep {
group1 {
psels = <NRF_PSEL(UART_TX, 2, 2)>,
<NRF_PSEL(UART_RX, 2, 0)>;
low-power-enable;
};
};
};
&uart21 {
status = "okay";
current-speed = <115200>;
pinctrl-0 = <&uart21_default>;
pinctrl-1 = <&uart21_sleep>;
pinctrl-names = "default", "sleep";
};
Another thing I observed is that the `psels` fields in the `zephyr.dts` file would only have 1 of the 2 pins set as connected (the leading bit of the psel register). Is this expected?
