I've also used O_NDELAY, which is a personal preference, to open the fd in non-blocking mode. Int serial_fd = open('/dev/ttyAMA0', O_RDWR | O_NOCTTY | O_NDELAY) You open the descriptor normally, making sure to use O_NOCTTY (see man 2 open), and substituting the appropriate device node: #include Strcpy(str_send, 'This is another test string.The linux UART API (really, the POSIX termios API, but you should use the system man pages for implementation specifics everything is mostly in man 3 termios) creates a file descriptor that can be used for normal read(), write() and also poll() or select(), and therefore can be used to respond to incoming data via interrupt. Strcpy(str_send, 'This is a test string.') Unsigned char str_recv // recv data buffer Then, when the loop starts, Arduino sends back every character received by Serial (like an 'echo').Ĭhar mode= // 8 data bits, no parity, 1 stop bitĬhar str_send // send data buffer The sketch at first initializes the Serial port: the speed is 57600 baud, and the communication is done, as default, in ' 8N1' format, which means 8 data bits, no parity, 1 stop bit. In order to test the Serial communication with Arduino, at first I created a minimal and simple sketch using Arduino IDE, and flashed it on the Arduino Nano. On opposite, the original Arduino Nano use a more expensive FTDI chip, as far as I know. The drivers for Windows can be easily found in Internet by searching 'CH-340 drivers' on Raspbian Jessie Lite (January 2017), I did not need to install any driver. In fact, I am using a cheap 'made in China' Arduino Nano (price: 2 euro/piece) bought on AliExpress, which equips the USB-to-serial converter chip called HL-340 ( CH-340). In addition to that, the 'lsusb' command returns an additional device:īus 001 Device 004: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter By evaluating the 'delta' between the 2 pictures above, it is possible to understand that there are 2 more 'dev' devices: 'serial' and 'ttyUSB0'.

C serial port example on raspberry pi