Difference between revisions of "Transclusion: IOT-GATE-iMX8: RS485 / RS232"
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== RS485 / RS232 Mode Selection == | == RS485 / RS232 Mode Selection == | ||
The UART mode is stored in the U-Boot environment.<br> | The UART mode is stored in the U-Boot environment.<br> | ||
| − | U-Boot | + | U-Boot environment commands are used to set/get the UART mode. |
=== Set RS485 mode === | === Set RS485 mode === | ||
<pre> | <pre> | ||
| − | root@iot-gate-imx8:~# | + | root@iot-gate-imx8:~# fw_setenv uart_mode rs485 |
root@iot-gate-imx8:~# reboot | root@iot-gate-imx8:~# reboot | ||
</pre> | </pre> | ||
=== Set RS232 mode === | === Set RS232 mode === | ||
<pre> | <pre> | ||
| − | root@iot-gate-imx8:~# | + | root@iot-gate-imx8:~# fw_setenv uart_mode rs232 |
root@iot-gate-imx8:~# reboot | root@iot-gate-imx8:~# reboot | ||
</pre> | </pre> | ||
| Line 52: | Line 52: | ||
root@iot-gate-imx8:~# fw_printenv uart_mode | root@iot-gate-imx8:~# fw_printenv uart_mode | ||
</pre> | </pre> | ||
| + | '''Note:''' The default port mode is RS485. The port operates in this mode in case of the variable ''uart_mode'' is assigned to an incorrect value or unset. | ||
== Example == | == Example == | ||
Latest revision as of 12:45, 5 December 2022
IOT-GATE-iMX8 / SBC-IOT-iMX8 features a RS485 / RS232 port. Only half-duplex mode is supported for the RS485.
The RS485 / RS232 interface is routed to rear panel terminal block connector see drawing.
RS485 / RS232 connector pin-out:
| Pin Number | RS485 Functionality | RS232 Functionality |
| 1 | NEG A/- | TXD |
| 2 | NEG B/+ | RTS |
| 3 | Ground | Ground |
| 4 | NC | CTS |
| 5 | NC | RXD |
| 6 | Ground | Ground |
Contents
RS485 / RS232 Mode Selection
The UART mode is stored in the U-Boot environment.
U-Boot environment commands are used to set/get the UART mode.
Set RS485 mode
root@iot-gate-imx8:~# fw_setenv uart_mode rs485 root@iot-gate-imx8:~# reboot
Set RS232 mode
root@iot-gate-imx8:~# fw_setenv uart_mode rs232 root@iot-gate-imx8:~# reboot
Get UART mode
root@iot-gate-imx8:~# fw_printenv uart_mode
Note: The default port mode is RS485. The port operates in this mode in case of the variable uart_mode is assigned to an incorrect value or unset.
Example
Serial terminal emulator application can be used to test the RS485 port.
- Use the following command to start Minicom with the user space device of the RS485 (/dev/ttymxc0).
root@iot-gate-imx8:~# minicom -D /dev/ttymxc0
- Follow the following steps to disable hardware flow control
- Open the menu "Configure Minicom" with CTRL-a followed by the letter 'o'.
- Select "Serial port setup"
- Press the letter 'f'.
- Press the letter 'h'.
- Press the letter 'i'.
- Press the Esc key twice.
- The characters that are typed in the terminal are transmitted to the RS485 port.
- The characters that are received from the RS485 port are displayed in the terminal.
- Press CTRL-a followed by the letter 'x' to exit from Minicom
