Software configuration

Published February 3, 2023 © GPL3+

Relay control with CAN BUS

In this tutorial we explain how to control the Relay Board V1.0.0 for Raspberry with can bus.

BeginnerProtip1 hour1,206

Things used in this project

Hardware components

Raspberry Pi 4 Model B

Ii is possible to use all Raspberry Pi B with 40 pins header

Raspberry Pi Compute Module 4

Raspberry Pi Compute Module 4 IO Board

CAN BUS Dual Base V2.1.4 Shield for Raspberry

Relays Board V1.0.0

Software apps and online services

Raspberry Pi Raspbian

Hand tools and fabrication machines

Multitool, Screwdriver

Servo Motor, Premium Male/Male Jumper Wires

Story

SG Electronic Systems was born as a support to the Open Hardware projects. Our experience allows us to support the Open Hardware team in the development of new electronic systems and in their distribution. We have a long experience in Fieldbus applications as: CAN BUS, RS-232, RS-422/485, Ethernet.

In this tutorial we explain how to control the Relay Board with can bus. The hardware setup is composed by Master Board (to send CAN commands) and Slave Board (for Relays control). The Master Board is the official carrier CM4IO with a CM4 module and CAN BUS Shield. The Slave Board is the Relay Board whit a Raspberry Pi 4 and DUAL CAN BUS Shield.

The CM4IO requires a 12 V DC power supply, instead the Relay board require a 5 V DC power supply (max allowed value is 5.1 V). On can side, the connection requires a a couple of wires for CAN High and CAN Low (CAN High is connected with CAN High, CAN Low is connected with CAN Low).

Software configuration

On both Raspberry Pi edit /boot/config.txt modify the following row

dtoverlay=mcp2515-can0, oscillator=16000000, interrupt=22dtoverlay=mcp2515-can1, oscillator=16000000, interrupt=25

Run the following command:

pi@raspberrypi ~ $ dmesg | grep -i can

This is the output:

[ 13.197388] CAN device driver interface[ 15.375846] mcp251x spi0.0 can1: bit-timing not yet defined[ 15.382408] mcp251x spi0.1 can0: bit-timing not yet defined

From the output it is possible to observe that can0 is associated to spi0.1 and can1 to spi0.0.

Respect the board shown in figure 1 the interface can0 is located in SPI0.1(X2 connector) and can1 in SPI0.0(X1 connector).

After your raspberry has been booted, go to home directory:

cd /home/pi/nano can-start.sh

add these lines to the script

#!/bin/sh#Canip link set can0 up type can bitrate 1000000ip link set can1 up type can bitrate 1000000

Run the script:

sudo sh can-start.sh

Before to start test with Python, you must test if the can bus communication works. You can use standard can bus commands to use the peripheral:

on first board run candump can0 -> to monitoring can bus traffic

on second board cansend can0 7DF#0201050000000000 -> to send canbus commands

If CAN BUS communication works fine, you can proceed with next step.

On our demo we use Python, all our scripts are ready for download. For scripts execution it is mandatory to install Python, and several libraries for GPIO, can and arguments parser on both boards. Run the following commands:

sudo apt-get update
sudo apt-get install python3-pip
sudo pip3 install RPi.GPIO
sudo pip3 install argparse
sudo pip3 install can

On Slave Board we can run the script

relay_mcp2515.py

python relay_mcp2515.py

The slave script switch off all relays and start CAN message listen with Id 0x1B2

Start can bus on Master Board and run the script

set_can_relay.py

to send CAN commads. The script execution requires two argument Relay number (from 1 to 8) and Relay status (on/off), for example to switch on relay 1 use

python set_can_relay.py --rel 8 --status on

instead to switch off relay 8 use

python set_can_relay.py --rel 1 --status off

Code

#print ("SG Electronic Systems srls")
#print ("Relay V1.0.0 Relays CAN controlled")
# instal ---->>>  pip install python-can
import can
import time
import argparse
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)

parser = argparse.ArgumentParser()
parser.add_argument('--rel',
                    dest='relay',
                    help='Define Relay number to set',
                    type=int
                    )
parser.add_argument('--status',
                    dest='status',
                    help='Define Relay status on/off'
                    )					
args = parser.parse_args()
print('Set relay', args.relay, args.status)


#Led 1 CAN BUS Board
GPIO.setup(27,GPIO.OUT)
GPIO.output(27,GPIO.LOW)
#Led 2 CAN BUS Board
GPIO.setup(4,GPIO.OUT)
GPIO.output(4,GPIO.LOW)
can_interface = 'can0'
can_data = [0,0]

if (args.relay >= 1 and args.relay<=8):
	can_data[0]=args.relay
	if (args.status == 'on'):
		can_data[1] = 1
	elif (args.status == 'off'):
		can_data[1] = 0 
	else:
		print("Invalid relay status")
		can_data[1] = 5
	message = can.Message(arbitration_id=0x1B2, is_extended_id=True, data=can_data)
	bus = can.Bus(interface='socketcan', channel='can0', receive_own_messages=True)
	# send a message
	bus.send(message, timeout=0.2)
else:
	print("Invalid relay number")

# install ---->>>  pip install python-can
import can
import time
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
print ("SG Electronic Systems srls")
print ("Relay V1.0.0 Relays CAN controlled")
#Relay 1
GPIO.setup(6,GPIO.OUT)
GPIO.output(6,GPIO.HIGH)
#Relay 2
GPIO.setup(12,GPIO.OUT)
GPIO.output(12,GPIO.HIGH)
#Relay 3
GPIO.setup(13,GPIO.OUT)
GPIO.output(13,GPIO.HIGH)
#Relay 4
GPIO.setup(19,GPIO.OUT)
GPIO.output(19,GPIO.HIGH)
#Relay 5
GPIO.setup(16,GPIO.OUT)
GPIO.output(16,GPIO.HIGH)
#Relay 6
GPIO.setup(26,GPIO.OUT)
GPIO.output(26,GPIO.HIGH)
#Relay 7
GPIO.setup(20,GPIO.OUT)
GPIO.output(20,GPIO.HIGH)
#Relay 8
GPIO.setup(21,GPIO.OUT)
GPIO.output(21,GPIO.HIGH)
print ("All relays off")
#Led 1 CAN BUS Board
GPIO.setup(27,GPIO.OUT)
GPIO.output(27,GPIO.LOW)
#Led 2 CAN BUS Board
GPIO.setup(4,GPIO.OUT)
GPIO.output(4,GPIO.LOW)
can_interface = 'can0'
bus = can.interface.Bus(can_interface, bustype='socketcan',bitrate=500000)

def led1_blink():
	GPIO.output(27,GPIO.HIGH)
	time.sleep(1/100)
	GPIO.output(27,GPIO.LOW)
	
def led2_blink():
   	GPIO.output(4,GPIO.HIGH)
	time.sleep(1/100)
	GPIO.output(4,GPIO.LOW)

def rel_on(rel_num):
	if (rel_num == 1):
		GPIO.output(6,GPIO.LOW)
	elif (rel_num == 2):
		GPIO.output(12,GPIO.LOW)
	elif (rel_num == 3):
		GPIO.output(13,GPIO.LOW)
	elif (rel_num == 4):
		GPIO.output(19,GPIO.LOW)
	elif (rel_num == 5):
		GPIO.output(16,GPIO.LOW)
	elif (rel_num == 6):
		GPIO.output(26,GPIO.LOW)
	elif (rel_num == 7):
		GPIO.output(20,GPIO.LOW)
	elif (rel_num == 8):
		GPIO.output(21,GPIO.LOW)	

def rel_off(rel_num):
	if (rel_num == 1):
		GPIO.output(6,GPIO.HIGH)
	elif (rel_num == 2):
		GPIO.output(12,GPIO.HIGH)
	elif (rel_num == 3):
		GPIO.output(13,GPIO.HIGH)
	elif (rel_num == 4):
		GPIO.output(19,GPIO.HIGH)
	elif (rel_num == 5):
		GPIO.output(16,GPIO.HIGH)
	elif (rel_num == 6):
		GPIO.output(26,GPIO.HIGH)
	elif (rel_num == 7):
		GPIO.output(20,GPIO.HIGH)
	elif (rel_num == 8):
		GPIO.output(21,GPIO.HIGH)			

while True:
	message = bus.recv()
	print("Message Received", message)
	if (message.arbitration_id == 0x1B2):
		led1_blink()
		if (message.data[0] >= 1 and message.data[0]<=8):
			led2_blink()
			print("Relay ",  message.data[0])
			if (message.data[1] == 1):
				print("On ")
				rel_on(message.data[0])
			elif (message.data[1] == 0):
				print("Off ")
				rel_off(message.data[0])

Credits

Pier8283

10 projects • 5 followers

Relay control with CAN BUS

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Software configuration

Schematics

System connectons

Code

Send CAN BUS command to relay board

Receive CAN BUS command for relay setting

Credits

Pier8283

Comments

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Relay control with CAN BUS

Relay control with CAN BUS

Things used in this project

Hardware components

Software apps and online services

Hand tools and fabrication machines

Story

Software configuration

Schematics

System connectons

Code

Send CAN BUS command to relay board

Receive CAN BUS command for relay setting

Credits

Pier8283

Comments

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