Software-based serial port module for Raspberry Pi.
This is built on top of https://github.com/adrianomarto/soft_uart.
This module creates up to 8 software-based serial ports using configurable pairs of GPIO pins. The serial port will appear as /dev/ttySOFT[X].
- Works exactly as hardware-based serial ports.
- Works with any application, e.g. cat, echo, minicom.
- Configurable baud rate.
- TX buffer of 256 bytes.
- RX buffer managed by the kernel.
Fetch the source:
git clone --depth 1 https://github.com/IcySakura/rpi4b_soft_uarts
Install the package raspberrypi-kernel-headers:
sudo apt-get install raspberrypi-kernel-headers
Run make and make install, as usual.
cd soft_uart
make
sudo make install
I haven't tried cross-compiling this module, but it should work as well.
Loading the module:
sudo insmod soft_uart.ko
- gpio_tx: int [default = {2, 4, 15, 17, 22, 24, 9, 8}]
- gpio_rx: int [default = {3, 14, 18, 27, 23, 10, 25, 11}]
Please modify the above-mentioning two parameters for different GPIO pins.
The device will appear as /dev/ttySOFT[X]. Use them as any usual TTY device.
You must be included in the group dialout. You can verify in what groups you are included by typing groups. To add an user to the group dialout, type:
sudo usermod -aG dialout <username>
Usage examples:
minicom -b 4800 -D /dev/ttySOFT0
cat /dev/ttySOFT0
echo "hello" > /dev/ttySOFT0
When choosing the baud rate, take into account that:
- The Raspberry Pi is not very fast.
- You will probably not be running a real-time operating system.
- There will be other processes competing for CPU time.
As a result, you can expect communication errors when using fast baud rates. So I would not try to go any faster than 4800 bps.