DART-MX8M UART: Difference between revisions
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= Disabling UART2 = | = Disabling UART2 = | ||
To disable UART2 edit arch/arm64/boot/dts/{{#ifeq: {{#var:HARDWARE_NAME}}|DART-MX8M|{{#ifeq: {{#var:YOCTO_NAME}}|Morty|variscite/imx8m-var-dart-common.dtsi|freescale/fsl-imx8mq-var-dart-common.dtsi}}|freescale/fsl-imx8mm-var-dart.dts}} under kernel source directory and modify | To disable UART2 edit {{#ifeq: {{#var:ANDROID_NAME}} | Pie |{{#var:BUILD_FOLDER}}/{{#var:BUILD_FOLDER_ANDROID}}/variscite/kernel_imx/}}arch/arm64/boot/dts/{{#ifeq: {{#var:HARDWARE_NAME}}|DART-MX8M|{{#ifeq: {{#var:YOCTO_NAME}}|Morty|variscite/imx8m-var-dart-common.dtsi|freescale/fsl-imx8mq-var-dart-common.dtsi}}|freescale/fsl-imx8mm-var-dart.dts}} under kernel source directory and modify | ||
<pre> | <pre> | ||
Revision as of 03:49, 22 January 2020
DART-MX8M UART Overview
All 4 UARTs on DART-MX8M are enabled by default.
UART1 is connected to debug console, UART2 and UART3 are connected to J12 header on DART-MX8M carrier board, 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
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
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 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.