MX8 UART: Difference between revisions
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= {{#var:HARDWARE_NAME}} UART Overview = | = {{#var:HARDWARE_NAME}} UART Overview = | ||
{{#ifeq: {{#var:HARDWARE_NAME}} | VAR-SOM-MX8X | | {{#ifeq: {{#var:HARDWARE_NAME}} | VAR-SOM-MX8X | | ||
All 4 UARTs on {{#var:HARDWARE_NAME}} are enabled by default.<br> | On VAR-SOM-MX8X up to 4 UARTS can be used. All 4 UARTs on {{#var:HARDWARE_NAME}} are enabled by default.<br> | ||
UART0 | UART3 is used as for debug console, UART0,UART1,UART2 are connected to J18 header on Symphony-Board.<br> | ||
UART0 is connected to Bluetooth module on SOM, it can be used on J18 only when BT is disabled.<br> | |||
Only UART0,UART1 have RTS and CTS lines. | |||
Inspect the carrier board datasheet or schematics for the exact pinout.<br> | Inspect the carrier board datasheet or schematics for the exact pinout.<br> | ||
| | | | ||
On VAR-SOM-MX8 UART1 | On VAR-SOM-MX8 up to 5 UARTS can be used. UART0,UART1,UART2,UART4 are enabled, UART3 is disabled as it shares pins with the second Ethernet controller, UART5 is not defined.<br> | ||
UART0 is used for debug console, UART1,UART2,UART4 are connected to J18 header on Symphony-Board, UART3 is connected to J30 header on Symphony-Board (not assembled by default).<br> | |||
UART1 is connected to Bluetooth module on SOM, it can be used on J18 only when BT is disabled.<br> | |||
Only UART0,UART1,UART3 have RTS and CTS lines.<br> | |||
Inspect the carrier board datasheet or schematics for the exact pinout.<br> | Inspect the carrier board datasheet or schematics for the exact pinout.<br> | ||
On SPEAR-MX8 UART1 | On SPEAR-MX8 up to 5 UARTS can be used. UART0,UART1,UART2 are enabled, UART3,UART4 are not defined (UART3 shares pins with the second Ethernet controller).<br> | ||
UART0 is used for debug console, UART0,UART2 are connected to J26 header on SPEAR-CustomBoard, UART3,UART4 are connected to J20 header on on SPEAR-CustomBoard .<br> | |||
UART1 is connected to Bluetooth module on SOM, it can be used only when BT is disabled (not exported on SPEAR-CustomBoard) .<br> | |||
Only UART0,UART1,UART3 have RTS and CTS lines.<br> | |||
Inspect the carrier board datasheet or schematics for the exact pinout.<br> | Inspect the carrier board datasheet or schematics for the exact pinout.<br> | ||
}} | }} | ||
= UART naming under Linux = | = UART naming under Linux = | ||
The Linux devices corresponding to | The Linux devices corresponding to UART0 - UART4 are /dev/ttyLP0 - /dev/ttyLP4 respectively. | ||
{{#ifeq: {{#var:HARDWARE_NAME}} | VAR-SOM-MX8X | | {{#ifeq: {{#var:HARDWARE_NAME}} | VAR-SOM-MX8X | | ||
= Testing | = Testing UART1 = | ||
Short J18.3 and J18.5 pins and run the following commands: | Short J18.3 and J18.5 pins and run the following commands: | ||
| Line 39: | Line 40: | ||
<br>For each invocation of echo command the "hello" string should appear on the terminal. | <br>For each invocation of echo command the "hello" string should appear on the terminal. | ||
= Testing | = Testing UART2 = | ||
Short J18.7 and J18.9 pins and run the following commands: | Short J18.7 and J18.9 pins and run the following commands: | ||
| Line 49: | Line 50: | ||
<br>For each invocation of echo command the "hello" string should appear on the terminal. | <br>For each invocation of echo command the "hello" string should appear on the terminal. | ||
| | | | ||
= Testing | = Testing UART2 on VAR-SOM-MX8 = | ||
Short J18. | 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 | ||
| Line 62: | Line 62: | ||
For each invocation of echo command the "hello" string should appear on the terminal. | For each invocation of echo command the "hello" string should appear on the terminal. | ||
= Testing | = Testing UART4 on VAR-SOM-MX8 = | ||
Short J18.7 and J18.9 pins and run the following commands: | |||
<pre> | |||
stty -F /dev/ttyLP4 -echo -onlcr 115200 | |||
cat /dev/ttyLP4 & | |||
echo hello > /dev/ttyLP4 | |||
</pre> | |||
= Testing UART2 on SPEAR-MX8 = | |||
Short J26.17 and J26.19 pins and run the following commands: | Short J26.17 and J26.19 pins and run the following commands: | ||
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= Disabling UART2 = | = Disabling UART2 = | ||
To disable | To disable UART1 edit arch/arm64/boot/dts/freescale/fsl-imx8qxp-var-som-common.dtsi under kernel source directory and modify | ||
<pre> | <pre> | ||
| Line 97: | Line 106: | ||
Other UARTs can be disabled in the similar manner. | Other UARTs can be disabled in the similar manner. | ||
| | | | ||
= Disabling | = Disabling UART2 = | ||
To disable | 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 | ||
<pre> | <pre> | ||
Revision as of 13:08, 1 December 2019
UART Overview
On VAR-SOM-MX8 up to 5 UARTS can be used. UART0,UART1,UART2,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,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,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. UART0,UART1,UART2 are enabled, UART3,UART4 are not defined (UART3 shares pins with the second Ethernet controller).
UART0 is used for debug console, UART0,UART2 are connected to J26 header on SPEAR-CustomBoard, UART3,UART4 are connected to J20 header on on SPEAR-CustomBoard .
UART1 is connected to Bluetooth module on SOM, it can be used only when BT is disabled (not exported on SPEAR-CustomBoard) .
Only UART0,UART1,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.