RS485/I2C/SPI/Serial Controlled 6 Channel Relay Control Board

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A RS485/Serial/I2C/SPI controlled 6 channel Relay with built in ATtiny2313 controller and LM7805 power supply system for home automation or electrical equipment control.

The board can control upto 6 relays using serial (TTL Serial,I2C or SPI) or RS485 connection thus saving the precious pins of your microcontroller.

The board can be used along with Arduino, AVR or PIC boards.

PC based Control Software along with source code is included for easy application development.

The Board can be used as

RS485 controlled 6 channel Relay Module
Serial (TTL) controlled 6 channel Relay Module
SPI controlled 6 channel Relay Module
I2C controlled 6 channel Relay Module


The board consists of 6 SPDT relays rated at 12 amps (MAX) which are controlled by a 20 pin ATtiny2313A controller.The ATtiny2313A controller is interfaced with a MAX485 based RS485 transceiver chip for remote control of the relays .

The 6 relays on the board can be remotely controlled from a PC using either RS485 or Serial Protocol(TX,RX).The board also has provision for other serial interfaces like TTL Serial, I2C(TWI) or SPI which can be used for controlling the relays.This makes it easy to control the relays from an Arduino board ,8051 controller ,PIC or AVR without sacrificing to many io pins of the microcontroller.

The built in microcontroller helps you to implement and decode serial protocols like Modbus over the RS485 protocol

The variety of serial interfaces makes this board ideal for implementing home automation or electrical equipment control. You can use two or more boards in a networked fashion for protocols like RS485,Serial or SPI to increase the number of Relay channels.The address of the individual boards can be set easily using jumpers .

The Power for 6 relays is provided by the onboard 7805 regulator and you can use any standard 12V DC adapter for powering the board .The 6 built in LED's helps you to visualize the state of 6 relays on the board.Extra power(+5V,+12V) and Ground pins are also provided.

Free and open source source code written in C# is provided for application development on the PC.


6 SPDT Relays rated at 12 Amps(Max)
Silver plated Contacts for long Life
Build in ATtiny2313A Microcontroller for processing Serial Protocols (eg Modbus)
MAX485 based RS485 port for interfacing with industrial networks
Capable of controlling 6 relays using SPI
Capable of controlling 6 relays using I2C or TWI
RS485 based 6 channel Relay Control
Open source code for developing PC side control Software
Jumpers for selecting network Address(RS485)
Ideal for building networked(RS485) Home / Factory Automation
Build in power supply module
LED's for indicating individual relay status (ON/OFF)
Extra +12V,+5V and ground Pins
Terminal Block connectors for relay outputs
6 pin AVR ISP connector for programming on board ATtiny2313A
Dimensions 120mm (length) X 82 mm(width)
Double Sided FR4 PCB


Home Automation
Factory Automation
Remote Electrical device Control
Simple SCADA system

Circuit Diagram / SourceCodes

Circuit diagram and source code for ATtiny based RS485 controlled 6 channel relay board

The Circuit diagram can be found in our github repo or can be downloaded from here

All the sourcecodes,circuit diagrams are available on our github page.

User Manual

The user manual for the ATtiny2313A Serial/RS485 Relay Control board can be found here.

Official page for our 6 channel RS485 Relay module is here.