MX8 UART: Difference between revisions
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<!-- Set release according to "release" parameter in URL and use | <!-- Set release according to "release" parameter in URL and use RELEASE_DUNFELL_V1.1_VAR-SOM-MX8 as default | ||
--> {{# | --> {{INIT_RELEASE_PARAM|RELEASE_DUNFELL_V1.1_VAR-SOM-MX8}} <!-- | ||
--> {{#lst: | --> {{#lst:Yocto_Platform_Customization|{{#var:RELEASE_PARAM}}}} <!-- | ||
--> {{PageHeader|{{#var:HARDWARE_NAME}} UART}} {{DocImage|category1=Yocto|category2={{#var:HARDWARE_NAME}} | --> {{#lst:Debian_Platform_Customization|{{#var:RELEASE_PARAM}}}} <!-- | ||
--> {{PageHeader|{{#var:HARDWARE_NAME}} UART}} {{DocImage|category1=Yocto|category2=Debian}} [[Category:{{#var:HARDWARE_NAME}}]] __toc__ | |||
= {{#var:HARDWARE_NAME}} UART Overview = | = {{#var:HARDWARE_NAME}} UART Overview = | ||
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Short J18.3 and J18.5 pins and run the following commands: | Short J18.3 and J18.5 pins and run the following commands: | ||
<pre> | <pre> | ||
stty -F /dev/ttyLP1 -echo -onlcr 115200 | # stty -F /dev/ttyLP1 -echo -onlcr 115200 | ||
cat /dev/ttyLP1 & | # cat /dev/ttyLP1 & | ||
echo hello > /dev/ttyLP1 | # echo hello > /dev/ttyLP1 | ||
</pre> | </pre> | ||
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Short J18.7 and J18.9 pins and run the following commands: | Short J18.7 and J18.9 pins and run the following commands: | ||
<pre> | <pre> | ||
stty -F /dev/ttyLP2 -echo -onlcr 115200 | # stty -F /dev/ttyLP2 -echo -onlcr 115200 | ||
cat /dev/ttyLP2 & | # cat /dev/ttyLP2 & | ||
echo hello > /dev/ttyLP2 | # echo hello > /dev/ttyLP2 | ||
</pre> | </pre> | ||
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Short J18.3 and J18.5 pins and run the following commands: | Short J18.3 and J18.5 pins and run the following commands: | ||
<pre> | <pre> | ||
stty -F /dev/ttyLP2 -echo -onlcr 115200 | # stty -F /dev/ttyLP2 -echo -onlcr 115200 | ||
cat /dev/ttyLP2 & | # cat /dev/ttyLP2 & | ||
echo hello > /dev/ttyLP2 | # echo hello > /dev/ttyLP2 | ||
</pre> | </pre> | ||
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Short J18.7 and J18.9 pins and run the following commands: | Short J18.7 and J18.9 pins and run the following commands: | ||
<pre> | <pre> | ||
stty -F /dev/ttyLP4 -echo -onlcr 115200 | # stty -F /dev/ttyLP4 -echo -onlcr 115200 | ||
cat /dev/ttyLP4 & | # cat /dev/ttyLP4 & | ||
echo hello > /dev/ttyLP4 | # echo hello > /dev/ttyLP4 | ||
</pre> | </pre> | ||
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Short J26.17 and J26.19 pins and run the following commands: | Short J26.17 and J26.19 pins and run the following commands: | ||
<pre> | <pre> | ||
stty -F /dev/ttyLP2 -echo -onlcr 115200 | # stty -F /dev/ttyLP2 -echo -onlcr 115200 | ||
cat /dev/ttyLP2 & | # cat /dev/ttyLP2 & | ||
echo hello > /dev/ttyLP2 | # echo hello > /dev/ttyLP2 | ||
</pre> | </pre> | ||
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'''On SPEAR-MX8''' modify arch/arm64/boot/dts/freescale/fsl-imx8qxp-var-spear-common.dtsi in the same manner. | '''On SPEAR-MX8''' modify arch/arm64/boot/dts/freescale/fsl-imx8qxp-var-spear-common.dtsi in the same manner. | ||
}} | }} | ||
{{#vardefine:UART_PREFIX|LP}} | |||
<!-- | |||
= Configuring RS485 Half-Duplex = | |||
{{#lst:Yocto_Platform_Customization|RS485_HALF_DUPLEX}} | |||
--> | |||
Latest revision as of 15:26, 6 June 2023
This page is using the default release RELEASE_DUNFELL_V1.1_VAR-SOM-MX8.
To view this page for a specific Variscite SoM and software release, please follow these steps:
- Visit variwiki.com
- Select your SoM
- Select the software release
VAR-SOM-MX8 UART Overview
On VAR-SOM-MX8 up to 5 UARTS can be used.
By default, UART0, UART1, UART2 and UART4 are enabled, UART3 is disabled as it shares pins with the second Ethernet controller. UART5 is not defined.
UART0 is used for debug console, UART1, UART2 and UART4 are connected to J18 header on Symphony-Board. UART3 is connected to J30 header on Symphony-Board (not assembled by default).
UART1 is connected to Bluetooth module on SOM, it can be used on J18 only when BT is disabled.
Only UART0, UART1 and UART3 have RTS and CTS lines.
Inspect the carrier board datasheet or schematics for the exact pinout.
On SPEAR-MX8 up to 5 UARTS can be used.
By default, UART0, UART1 and UART2 are enabled, and UART3 and UART4 are not defined (UART3 shares pins with the second Ethernet controller).
UART0 is used for debug console, UART0 and UART2 are connected to J26 header on SPEAR-CustomBoard. UART3 and UART4 are connected to J20 header on the SPEAR-CustomBoard.
UART1 is connected to the Bluetooth module on the SOM. it can be used only when BT is disabled (not exported on SPEAR-CustomBoard).
Only UART0, UART1 and UART3 have RTS and CTS lines.
Inspect the carrier board datasheet or schematics for the exact pinout.
UART naming under Linux
The Linux devices corresponding to UART0 - UART4 are /dev/ttyLP0 - /dev/ttyLP4 respectively.
Testing UART2 on VAR-SOM-MX8
Short J18.3 and J18.5 pins and run the following commands:
# stty -F /dev/ttyLP2 -echo -onlcr 115200 # cat /dev/ttyLP2 & # echo hello > /dev/ttyLP2
For each invocation of echo command the "hello" string should appear on the terminal.
Testing UART4 on VAR-SOM-MX8
Short J18.7 and J18.9 pins and run the following commands:
# stty -F /dev/ttyLP4 -echo -onlcr 115200 # cat /dev/ttyLP4 & # echo hello > /dev/ttyLP4
Testing UART2 on SPEAR-MX8
Short J26.17 and J26.19 pins and run the following commands:
# stty -F /dev/ttyLP2 -echo -onlcr 115200 # cat /dev/ttyLP2 & # echo hello > /dev/ttyLP2
For each invocation of echo command the "hello" string should appear on the terminal.
Disabling UART2
To disable UART2 on VAR-SOM-MX8 edit arch/arm64/boot/dts/freescale/fsl-imx8qxp-var-som-common.dtsi under kernel source directory and modify
&lpuart2 {
...
status = "okay";
};
to
&lpuart2 {
...
status = "disabled";
};
On SPEAR-MX8 modify arch/arm64/boot/dts/freescale/fsl-imx8qxp-var-spear-common.dtsi in the same manner.