The Toradex Carrier Board implements RS-485 using a single transceiver in a half-duplex communication mode, which means that one medium is shared for transmitting and receiving data. c_cflag | = B115200 if (tcsetattr (fd, TCSANOW, &tty ) ! = 0 ) Standard Baud RatesĪ fixed list of baud rates are pre-defined: Struct termios tty int fd int flags = O_RDWR | O_NOCTTY | O_NONBLOCK įd = open ( "/dev/verdin-uart1", flags ) Using C, use the struct termios to set the initial baud rate:
Then the port can be treated as as a regular file: # stty -F /dev/verdin-uart1 115200 Command-lineįrom userspace, one can use the command line utility stty to configure the serial speed. This section has information about how to configure and use the serial, including a sub-section for RS-485. dev/ttymxc0), not the Verdin symlinks (e.g. Those corresponding names are important because the Linux kernel logs will print the real device names (e.g. It will display the available Verdin pin-compatible UARTs and display the corresponding names used by the BSP. You can list the devices as follows: # ls -l /dev/verdin-uart* The BSP device name matches the signal name used in the SoM datasheet.ĭebug (console) for the main OS (Cortex-A)ĭebug for the real-time OS (Cortex-M) or general-purpose
The Apalis family has 4 pin-compatible UART interfaces.
Reading the SoM datasheet and the article Device Tree Customization are good starting points. You will need to check how many UARTs are available on your specific SoM and modify the default pin muxing. Keep in mind that each SoM may have additional UART interfaces that you can use at the tradeoff of breaking pin compatibility. In this section, you will learn what UART interfaces are available on all Toradex SoMs within a family. Toradex SoMs are pin-compatible within a family, as long as you use the default pin muxing from the Toradex Embedded Linux BSP. This article is very useful if you plan to use UART for communication with other devices - often using RS-232 or RS-485 - but if you just want to access the Linux terminal on the default debug UART, make sure to follow the first lessons from our Quickstart Guide or alternatively read the article Configuring Serial Port Debug Console (Linux/U-Boot). Since BSP 5, we provide standard Toradex names by family, such as /dev/apalis-uart1, /dev/colibri-uarta and verdin-uart1, to enhance pin compatibility on a software level. Serial port (UART) access from userspace on Linux is provided through TTY devices under /dev.
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