DESK-MX8M-L/Peripherals/UART
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| History | |||
|---|---|---|---|
| ID# | Issue Date | Notes | |
| 30/12/2021 | First DESK-MX8M-L release | ||
| 27/02/2023 | DESK-MX8M-L-2.0.0 release | ||
Contents
Peripheral UART[edit | edit source]
Device tree configuration[edit | edit source]
ORCA SOM[edit | edit source]
Here below an example of device tree modifications to standard DAVE's kit for the ORCA SOM:
From imx8mp-mito8mplus.dtsi:
...
...
&uart4 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart4>;
assigned-clocks = <&clk IMX8MP_CLK_UART4>;
assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_80M>;
fsl,uart-has-rtscts;
status = "okay";
};
...
...
&iomuxc {
...
...
pinctrl_uart4: uart4grp {
fsl,pins = <
MX8MP_IOMUXC_ECSPI2_SCLK__UART4_DCE_RX 0x140
MX8MP_IOMUXC_ECSPI2_MOSI__UART4_DCE_TX 0x140
MX8MP_IOMUXC_ECSPI2_MISO__UART4_DCE_CTS 0x140
MX8MP_IOMUXC_ECSPI2_SS0__UART4_DCE_RTS 0x140
>;
};
MITO 8M Mini[edit | edit source]
Here below an example of device tree configuration used on standard DAVE's kit for the MITO 8M Mini SOM:
From imx8mm-mito8mmini.dts:
...
...
&uart1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_uart1>;
assigned-clocks = <&clk IMX8MM_CLK_UART1>;
assigned-clock-parents = <&clk IMX8MM_SYS_PLL1_80M>;
fsl,uart-has-rtscts;
status = "okay";
};
...
...
&iomuxc {
...
...
pinctrl_uart1_en: uart1_en {
fsl,pins = <
MX8MM_IOMUXC_SAI5_RXD3_GPIO3_IO24 0x19
>;
};
...
pinctrl_uart1: uart1grp {
fsl,pins = <
MX8MM_IOMUXC_UART1_RXD_UART1_DCE_RX 0x140
MX8MM_IOMUXC_UART1_TXD_UART1_DCE_TX 0x140
MX8MM_IOMUXC_UART3_RXD_UART1_DCE_CTS_B 0x140
MX8MM_IOMUXC_UART3_TXD_UART1_DCE_RTS_B 0x140
>;
};
...
...
Accessing the peripheral in ORCA SOM[edit | edit source]
Linux messages at boot time[edit | edit source]
... ... [ 0.755511] 30860000.serial: ttymxc0 at MMIO 0x30860000 (irq = 26, base_baud = 5000000) is a IMX [ 0.762356] 30880000.serial: ttymxc2 at MMIO 0x30880000 (irq = 27, base_baud = 5000000) is a IMX [ 0.771151] 30890000.serial: ttymxc1 at MMIO 0x30890000 (irq = 28, base_baud = 1500000) is a IMX [ 0.779648] printk: console [ttymxc1] enabled [ 0.798672] 30a60000.serial: ttymxc3 at MMIO 0x30a60000 (irq = 35, base_baud = 5000000) is a IMX ... ...
Usage with stty[edit | edit source]
N.B. UART mapping respect to ttymxcX is the following one:
UART1 (RS232) <-> ttymxc0 UART2 (Serial Port) <-> ttymxc1 UART3 (UART) <-> ttymxc2 UART4 (RS485) <-> ttymxc3 ...
root@desk-mx8mp:~# stty -F /dev/ttymxc0 115200 -echo -raw root@desk-mx8mp:~# cat /dev/ttymxc0 > test_ttymxc0.log & [1] 622 root@desk-mx8mp:~# echo "Test loopback" > /dev/ttymxc0 root@desk-mx8mp:~# cat test_ttymxc0.log Test loopback
Accessing the peripheral in MITO 8M Mini[edit | edit source]
Linux messages at boot time[edit | edit source]
... ... [ 0.724202] 30860000.serial: ttymxc0 at MMIO 0x30860000 (irq = 32, base_baud = 5000000) is a IMX [ 0.778356] 30890000.serial: ttymxc1 at MMIO 0x30890000 (irq = 34, base_baud = 1500000) is a IMX [ 0.787035] printk: console [ttymxc1] enabled ... ...
Usage with stty[edit | edit source]
N.B. UART mapping respect to ttymxcX is the following one:
UART1 (RS232/RS485/RS422 port DB9) <-> ttymxc0 UART2 (Serial Port) <-> ttymxc1 UART3 (PMOD) <-> ttymxc2 UART4 (UART for Cortex-M4) <-> ttymxc3 ...
root@desk-mx8mm:~# stty -F /dev/ttymxc0 115200 -echo -raw root@desk-mx8mm:~# cat /dev/ttymxc0 > test_ttymxc0.log & [1] 363 root@desk-mx8mm:~# echo "Test loopback" > /dev/ttymxc0 root@desk-mx8mm:~# cat test_ttymxc0.log Test loopback
Additional information[edit | edit source]
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
