DESK-MX6UL-L/Peripherals/UART

History
Version	Issue Date	Notes
1.0.0	Apr 2021	First DESK release

Contents

Peripheral UARTEdit

Device tree configurationEdit

Here below an example of device tree configuration used on standard DAVE's kit for the AXEL ULite SOM:

From the Carrier imx6ul-lynx-som0013-cb002f.dts device tree:

&uart2 {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_uart2_flow>;
        fsl,uart-has-rtscts;
        status = "okay";
};

From imx6qdl-axelcommon.dtsi:

&iomuxc {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_hog_gpios>;

        imx6ul-lynx {
...
...
            pinctrl_uart2_flow: uart2grp-flow {
                fsl,pins = <
                        MX6UL_PAD_UART2_TX_DATA__UART2_DCE_TX 0x1b0b1
                        MX6UL_PAD_UART2_RX_DATA__UART2_DCE_RX 0x1b0b1
                        MX6UL_PAD_UART2_CTS_B__UART2_DCE_CTS  0x1b0b1
                        MX6UL_PAD_UART2_RTS_B__UART2_DCE_RTS  0x1b0b1
                >;
        };
...
...

Accessing the peripheralEdit

Linux messages at boot timeEdit

...
...
[    0.424294] 2020000.serial: ttymxc0 at MMIO 0x2020000 (irq = 21, base_baud = 5000000) is a IMX
[    1.125015] console [ttymxc0] enabled
[    1.130189] 2024000.serial: ttymxc7 at MMIO 0x2024000 (irq = 22, base_baud = 5000000) is a IMX
[    1.140851] 21e8000.serial: ttymxc1 at MMIO 0x21e8000 (irq = 58, base_baud = 5000000) is a IMX
[    1.150972] 21ec000.serial: ttymxc2 at MMIO 0x21ec000 (irq = 59, base_baud = 5000000) is a IMX
...
...
root@imx6qxelk:~#

Usage with sttyEdit

N.B. UART mapping respect to ttymxcX is the following one:

UART1 <-> ttymxc0
UART2 <-> ttymxc1
UART3 <-> ttymxc2
UART4 <-> ttymxc3
UART5 <-> ttymxc4
UART6 <-> ttymxc5
UART7 <-> ttymxc6
UART8 <-> ttymxc7
...

root@desk-mx6ul-axelulite:~# stty -F /dev/ttymxc7 115200 -echo
root@desk-mx6ul-axelulite:~# cat /dev/ttymxc7 &
[1] 331
root@desk-mx6ul-axelulite:~# echo "Test loopback" > /dev/ttymxc7
root@desk-mx6ul-axelulite:~#

Additional informationEdit

Serial ports can be used through the standard serial programming API.

For detailed information, please refer to the Serial Programming HOWTO at Serial-Programming-HOWTO

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