8 channel I2C relay module board for Arduino and Raspberry Pi

You can directly connect this relay board to the Raspberry Pi or Arduino using just four wires.

Using the I2C 8-channel relay module with a Raspberry Pi - YouTube

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options

Board type: I2C
Relay voltage: 5V or 12V

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description

  • 8 channel relay module board with an I2C connection
  • control utility and shell script for Raspberry Pi and Linux, with source code
  • comes with example source code for Arduino
  • up to 8 boards can be connected to each I2C bus
  • each board can be assigned an I2C address between 0x20 and 0x27 by the DIP switch SW1
  • removable terminal blocks for easy assembly and disassembly
  • relays with SPDT switch contacts: Normally Open, Common, Normally Closed
  • can directly connect to 5V/3.3V/1.8V logic signals
  • separate power input for the relays to avoid glitches on the power lines of the digital circuits
Board connectors:
  • 5.5/2.1mm DC jack female connector for relay power input, center positive (CN22)
  • 4-pin 2.54mm pitch connector for logic power input and control connection (CN21)

relay module connectors
Board size 100 x 80 mm (3.94 x 3.15 inch)
Logic supply voltage 1.8-5.5VDC
Relay supply input current required for 5V version
 635 mA @ 5V input from CN22
Relay supply input current required for 12V version 267 mA @ 12V input from CN22
Relay contact ratings, resistive load
 7A 28VDC
10A 125VAC
7A 240VAC
Relay contact ratings, inductive load
 3A 120VAC
3A 28VDC
Relay contacts maximum voltage
 250VAC
110VDC
Relay contacts resistance, ON
 100mΩ max
Terminal block wire range
 AWG24-AWG12

Setup and use

  1. Connect the I2C signals and logic power supply to CN21
  2. Connect the relay power supply to CN22 jack (5VDC or 12VDC, depending on the relay voltage of the board)

The pinout for CN21 is:

relay module I2C connector pinout
CN21 pin
 pin name
1 (square)
 VDD (logic power supply input)
2
 GND (common power supply ground)
3
 SDA (I2C data)
4
 SCL (I2C clock)

Connect the relay board to a Raspberry Pi as:
Raspberry Pi P1 pin relay module
CN21 pin
 pin name
1
 1 (square)
 +3.3V (logic power supply input)
9
 2
 GND (common power supply ground)
3
 3
 SDA (I2C data)
5
 4
 SCL (I2C clock)

Connecting to a Raspberry Pi
Connect the relay board to an Arduino as:
Arduino pin
 relay module
CN21 pin
 pin name
power 5V
 1 (square) logic power supply input
power GND
 2
 GND (common power supply ground)
analog 4
 3
 SDA (I2C data)
analog 5
 4
 SCL (I2C clock)

Connecting to an Arduino
Example of controlling the relays on a Raspberry Pi board:

command line example
 explanation
relayctl setport 0
 turn all 8 relays OFF
relayctl setport 0b00001100
turn relay for CN3 and CN4 ON, all others OFF

relayctl setbit 0b10000000

 turn relay for CN8 ON, don't change the state of other relays
relayctl clearbit 0b01000001 turn relay for CN1 and CN7 OFF, don't change the state of other relays

Please read the the full documentation here.

Download the support package with examples and utilities for the I2C relay board. The package contains:

bin/linux.x86/relayctl
 relay control utility for 32-bit x86 Linux
bin/raspberry/relayctl
 relay control utility for the Raspberry Pi
src/arduino/relayboard_i2c.ino example source code to control the relay board from an Arduino
src/i2c-tools/relayboard_i2c.sh example shell script to control the relay board by Linux i2c-tools
src/relayctl/
 C source code for the relay control utility