ASYNC UART configuration error

Products & Technology XIAO
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1

Hello All,

I am trying to set up the ASYNC UART and I am getting the following error:
-ENOSYS: If configuration is not supported by the device or driver does not support setting configuration at runtime

To my understanding Noridc supports the Asyn UART which should include the Seeed Xiao sense nrf52480. Correct me if I am wrong?

Furthermore, nordic has a tutorial on how to use this UART configuartion so I am not sure why I am getting this error when I try to implement it.

What is the issue?
What else can I check to find the cause of this issue?

Any insights are much appreciated.

The following is the code that is relevant before the error:

Function called:
int configUART(const struct device *uart){

if (!device_is_ready(uart)) {

    return -ENODEV;

}

const struct uart_config uart_cfg = {

    .baudrate = 9600,

    .parity = UART_CFG_PARITY_NONE,

    .stop_bits = UART_CFG_STOP_BITS_1,

    .data_bits = UART_CFG_DATA_BITS_8,

    .flow_ctrl = UART_CFG_FLOW_CTRL_NONE

};

int err = uart_configure(uart, &uart_cfg);

if (err < 0) {

    return err;

}

return 0;

};

Main file code to start the uart

//----------------------UART INIT--------------------------//

    const struct device *uart = DEVICE_DT_GET(DT_NODELABEL(uart0));

    if (!uart) {

            LOG_ERR("Unable to get the UART binding");

            return -1;

    }

    err = configUART(uart);

    if (err < 0){

            LOG_ERR("ERROR Configuring UART: %d", err);

Device tree overlay set up:
&uart0{

current-speed = <9600>;

};

2

Hi there,
So just taking a wild guess I would look to the Board config(device tree), or the Overlay and be sure the Uart is set up and enabled.
HTH
GL :slight_smile: PJ :v:

3

Hey PJ:

I think I got the device tree correctly configured:

This is the default configuration in the xio_ble_common.dtsi:

&uart0 {

compatible = "nordic,nrf-uarte";

status = "okay";

current-speed = <115200>;

pinctrl-0 = <&uart0_default>;

pinctrl-1 = <&uart0_sleep>;

pinctrl-names = "default", "sleep";

};

Below is the pin default pin control:

uart0_default: uart0_default {

    group1 {

        psels = <NRF_PSEL(UART_TX, 1, 11)>;

    };

    group2 {

        psels = <NRF_PSEL(UART_RX, 1, 12)>;

        bias-pull-up;

    };

};

uart0_sleep: uart0_sleep {

    group1 {

        psels = <NRF_PSEL(UART_TX, 1, 11)>,

            <NRF_PSEL(UART_RX, 1, 12)>;

        low-power-enable;

    };

};

This is my overlay code:

&uart0 {

current-speed = <9600>;

};

I used an overlay because I needed to adjust the baud rate.

Is there anything else I need to do with the UART overlays?

4

I have done some more leg work and have found that the errors are compiling form similar structures as like the below:

static inline int z_impl_uart_configure(const struct device *dev,

                const struct uart_config *cfg)

{

#ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE

const struct uart_driver_api *api =

            (const struct uart_driver_api *)dev->api;

**if (api->configure == NULL) {**

** return -ENOSYS;**

}

return api->configure(dev, cfg);

#else

ARG_UNUSED(dev);

ARG_UNUSED(cfg);

return -ENOTSUP;

#endif

}

the api->configure value is null.
Upon finding this out I thought the async uart method would not be compatible but when looking at the devicetree set up for the uart the underlying nordic, nrf-uart-common.yaml file states that the Nordic nRF family UART is working with EasyDMA which is a prerequisite for using the async functionality.

Are there more setup that I need to do?

The tutorial by Nordic do not state otherwise.

5

Hi, there!

I think my problem is quite related to the original one. I am doing the exercise from the nrf Academy with only XIAO nrf52480 (attached to an expansion board), no nordic DK:

The solution code is here:

I am getting the -ENOSYS error on this line:

ret = uart_callback_set(uart, uart_cb, NULL);

and I don’t understand why. Is the UART-USB not supported on XIAO? Or XIAO’s configuration is somehow different from what nrf DK has for UART?

6

Alright, may be this will be useful for someone.

Based on this post:

The xiao ble sense board is using USB CDC for console, logging, etc, and the USB stack is not compatible with the Asynchronous API, only the Interrupt-driven API. But it is possible to enable the ASYNC api for the uart0 node by setting CONFIG_UART_0_INTERRUPT_DRIVEN=n and CONFIG_UART_0_ASYNC=y in your prj.conf file.

I wasn’t able to work out the provided example in the comments and make UART work via USB of nrf25840. However, I’ve added the following lines to my config:

CONFIG_UART_ASYNC_API=y
CONFIG_UART_0_INTERRUPT_DRIVEN=n

The last one cures the ENOSYS error.

Then, I’ve flashed my ESP32C3 with some Arduino sketch on reading/writing from/to Hardware UART and connected RX & TX ports of both ESP32C3 and nrf52840. Then I was able to use the serial monitor of ESP32C3 to read nrf52840 greeting and send back the values to toggle different LEDs. Basically, I’ve used my ESP32C3 board as a USB-UART converter for this exercise.

7

I have a similar question that relates. The nRF52840 has two UARTE’s and a USB. Serial and Serial1. I need two UART’s. It appears I can set up a RX/TX on D0 and D1. I’m not sure but I believe the standard Xiao nRF setup uses Serial for the Arudino USB connection. So that in standard set up, Serial1 is on D6 D7. But Adafruit has a TinyUSB that is my understand uses the nRF USB to send and receive serial data.

If, this is true, does this mean I can set up serial as D0 D1?

If not, there appears to be a software serial class called MySerial I don’t know how it works but my 2nd serial port has low demand for fast serial comms, so it might work.

Any suggestions?

8

Hi there,

And Welcome Here…

SO The Nrf52840 Has 2 Serial UARTS on the silicon, Serial & Serial1 and There is also the possibility to use a GPIO pin to “Bit_Bang” the data into the MCU pins (emulating a serial port functionality) Software Serial is that LIBRARY that enables that to work on a set of GPIO pins.
There is a Speed limitation on this method.
Search software serial and you will find all the info you should ever need, also some of the Xiao wiki’s use this tech to connect to certain peripherals. :+1:

HTH
GL :slight_smile: PJ :v:

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