Phytec L-1017e.A3 i.MX 8M Plus, Руководство пользователя

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L-1017e.A3 i.MX 8M Plus BSP Manual
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RS232/RS485
The phyCORE-i.MX 8M Plus supports up to 4 UART units. On the phyBOARD-Pollux, TTL level signals of UART1 (the
standard console) and UART4 are routed to Silicon Labs CP2105 UART to USB converter expansion. This USB is
brought out at Micro-USB connector X1. UART3 is at X6 (Expansion Connector) at TTL level. UART2 is connected to a
multi-protocol transceiver for RS-232 and RS-485, available at pin header connector
X2 at RS-232 level, or at RS-485
level.
The configuration of the multi-protocol transceiver is done by jumpers
JP3 and JP4 on the baseboard. For more
information about the correct setup please refer to the phyCORE-i.MX8MPlus/phyBOARD-Pollux Hardware Manual
section
UARTs .
The device tree representation for RS232 and RS485: https://git.phytec.de/linux-imx/tree/arch/arm64/boot/dts/
freescale/imx8mp-phyboard-pollux.dtsi?h=v5.10.72_2.2.0-phy9#n337
RS232
Display the current settings of a terminal in a human-readable format:
target$ stty -a
Configuration of the UART interface can be done with stty. For example:
target$ stty -F /dev/ttymxc1 115200 crtscts raw -echo
With a simple echo and cat, basic communication can be tested. Example:
host$ cat /dev/ttyUSB2
Make sure that the jumpers JP3 and JP4 on the phyBOARD-Pollux are set correctly and the baudrate
configuration has been done correctly set on the host side as well. Then:
target$ echo 123 > /dev/ttymxc1
The host should print out "123".
RS485
We use the same device tree node for RS-232 and RS-485. RS-485 mode can be enabled with ioctl TIOCSRS485. Also,
full-duplex support is also configured using ioctls. Have a look at our small example application rs485test , which is
also included in the BSP. The jumpers JP3 and JP4 need to be set correctly.
For easy testing, look at the linux-serial-test . This tool is called the IOCTL for RS485 and sends a constant stream of
data.