8serial-rpi

Drivers for Sequent Microsystems Eight Serial Ports HAT for Raspberry Pi

Setup

Enable I2C communication first:

sudo raspi-config

A good article about I2C on Raspberry can be found here.

If you use Ubuntu you need to install raspi-config first:

sudo apt update
sudo apt install raspi-config

Make sure you have all the tools you need:

sudo apt update
sudo apt-get install git build-essential

Usage

Kernel visible Serial ports and CAN

The card emulates 3 x SC16IS752 chips, each with two UART ports, and contains one MCP2515 CAN chip.

Setup: Edit the /boot/config.txt or /boot/firmware/config.txt for the new Raspbians, adding the following lines depending on the card ID

• ID = 0:

#UART ports enable
dtoverlay=sc16is752-i2c,int_pin=22,addr=0x6A,xtal=1843200
dtoverlay=sc16is752-i2c,int_pin=19,addr=0x6C,xtal=1843200
dtoverlay=sc16is752-i2c,int_pin=20,addr=0x6E,xtal=1843200
#CAN port 
dtparam=spi=on
dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=6
dtoverlay=spi-bcm2835
dtoverlay=spi-dma

• ID = 1:

#UART ports enable
dtoverlay=sc16is752-i2c,int_pin=22,addr=0x6B,xtal=1843200
dtoverlay=sc16is752-i2c,int_pin=19,addr=0x6D,xtal=1843200
dtoverlay=sc16is752-i2c,int_pin=20,addr=0x6F,xtal=1843200
#CAN port 
dtparam=spi=on
dtoverlay=mcp2515-can1,oscillator=16000000,interrupt=16
dtoverlay=spi-bcm2835
dtoverlay=spi-dma

After a restart open a terminal and run the following command ls /dev and you should see the ttySCx serial ports listed.

To check the CAN port run the following command dmesg | grep can0

The serial names that can be used and the correspondence with the card ports are as follows:

• dev/ttySC0 => RS232 PORT2
• dev/ttySC1 => RS485
• dev/ttySC2 = RS232 PORT3
• dev/ttySC3 = RS232 PORT1
• dev/ttySC4 = M-BUS
• dev/ttySC5 = RS422

The Linux kernel accepts only 8 emulated USART ports (dev/ttySC0 to dev/ttySC7) so you can not use all the UART ports generated by the two cards stacked on the same Raspberry PI with Linux drivers but you can implement your own for the remaining ports.

Quick test for the serial ports:

• Sending data :

sh -c 'echo -n "Text to send\n" >/dev/ttySC0'

• Receiving data (the recived string must contain LF or CR caracters):

cat /dev/ttySC0

For a complete reference of the CAN usage, please check out the LinuxJedi

One wire bus and additional features

Install the command:

git clone https://github.com/SequentMicrosystems/8serial-rpi.git
cd 8serial-rpi/
sudo make install

Now you can access the watchdog, one-wire bus, and button features of the Eight Serial Ports HAT for Raspberry Pi through the command "8serial". Use -h option for help:

8serial -h

If you clone the repository any update can be made with the following commands:

cd 8serial-rpi/  
git pull
sudo make install