StarSBC-6ULL RS232 example
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StarSBC-6ULL RS232 example
This tutorial shows how to send and receive data using RS232 interface on StarSBC-6ULL with communication extension board. The default Yocto image contains all required software tools.
Loop test
The extension board has two RS232 interfaces available so they may be connected to perform the test in a loop. All signals are available on the J101 and J201 connectors. They should be connected according to the following table:
| RS232-1 signal | RS232-2 signal |
|---|---|
| RS232-1 TXD (J101 pin 3) | RS232-2 RXD (J201 pin 8) |
| RS232-1 RXD (J101 pin 4) | RS232-2 TXD (J201 pin 7) |
| RS232-1 CTS (J101 pin 1) | RS232-2 RTS (J201 pin 10) |
| RS232-1 RTS (J101 pin 2) | RS232-2 CTS (J201 pin 9) |
Both interfaces are already defined in the default module device-tree and are recognized as /dev/ttymxc2 and /dev/ttymxc6 devices. The device files may be used directly for reading and writing and the bitrate may be set using the stty tool:
root@starsbc-6ull:~# stty -F /dev/ttymxc2 9600 crtscts root@starsbc-6ull:~# stty -F /dev/ttymxc6 9600 crtscts root@starsbc-6ull:~# cat /dev/ttymxc2 & [1] 465 root@starsbc-6ull:~# echo "123" > /dev/ttymxc6 123
