DART-MX8M UART: Difference between revisions
No edit summary |
No edit summary |
||
| Line 22: | Line 22: | ||
--> {{#switch:{{#var:HARDWARE_NAME}} | <!-- | --> {{#switch:{{#var:HARDWARE_NAME}} | <!-- | ||
--> DART-MX8M-MINI = VAR-SOM-MX8M-MINI | <!-- | --> DART-MX8M-MINI = VAR-SOM-MX8M-MINI | <!-- | ||
--> DART-MX8M-PLUS = VAR-SOM-MX8M-PLUS | <!-- | |||
--> {{#var:HARDWARE_NAME}} <!-- | --> {{#var:HARDWARE_NAME}} <!-- | ||
--> }} <!-- | --> }} <!-- | ||
Revision as of 10:07, 9 November 2020
UART Overview
On DART-MX8M all 4 UARTs are enabled by default.
UART1 is connected to debug console.
UART2 and UART3 are connected to J12 header on VAR-DT8MCustomBoard.
UART4 is connected to Bluetooth module.
On DART-MX8M SoMs without WIFI/BT module UART4 is also connected to J12 header.
See the carrier board datasheet for the exact pinout.
Only UART4 has RTS and CTS lines.
UART naming under Linux
The Linux devices corresponding to UART1 - UART4 are /dev/ttymxc0 - /dev/ttymxc3 respectively.
Testing UART2 on DART-MX8M
Short J12.4 and J12.6 pins and run the following commands:
stty -F /dev/ttymxc1 -echo -onlcr 115200 cat /dev/ttymxc1 & echo hello > /dev/ttymxc1
For each time you run this echo command the "hello" string should appear on the terminal.
Testing UART3 on DART-MX8M
Short J12.11 and J12.13 pins and run the following commands:
stty -F /dev/ttymxc2 -echo -onlcr 115200 cat /dev/ttymxc2 & echo hello > /dev/ttymxc2
For each invocation of echo command the "hello" string should appear on the terminal.
Disabling UART2
To disable UART2 on DART-MX8M edit arch/arm64/boot/dts/freescale/fsl-imx8mq-var-dart-common.dtsi under kernel source directory and modify
&uart2 {
...
status = "okay";
};
to
&uart2 {
...
status = "disabled";
};
Other UARTs can be disabled in the same manner.