This I2C 24-channel relay controller was designed to function as a shield for Particle Photon*.
Control relays from the cloud using WiFi connectivity or develop your own relay control firmware. Relay control is easy using our firmware examples in our GitHub repository. WiFi connectivity means you have easy access to this device from your home or office, or anywhere a WiFi signal is available!
Ideal for WiFi cloud controlled switching applications, including pumps, valves, solenoids, lights, and much more. Stay connected and in control without wires.
Stay Connected to the cloud and access this controller from anywhere in the world using Particle Photon. Don’t forget to visit our GitHub repository, which allows you to download and customize the firmware in this device for your specific needs.
This controller includes an on-board I2C expansion port, allowing an easy pathway to expansion for controlling more relays, reading sensors, or expanding to any I2C device we develop in the future. Up to eight MCP23017 based devices may be connected to a single I2C port. This controller counts as 2 devices.
This device provices 3 connections to each relay: Common, Normally Closed, and Normally Open. The Common connection is always connected to the Normally Closed connection when the relay is off. When the relay switches on, the Common connection is disconnected from the Normally Closed and Connected to the Normally Open. External loads may be wired to be off all the time and turn on when the relay turns on. Optionally, external loads may be wired to be on all the time, with the external load switching off when the relay is activated. Relays are controlled using the MCP230xx Series Programmable GPIO Port Expanders from Microchip Technology. The first MCP23017 on this circuit board has the address line A0 connected to ground. The second MCP23017 on this circuit board has the address line A0 connected to +5VDC. This prevents on-board address conflicts. The remaining address jumpers A1 and A2 are jumper selectable. Relays are controlled by a MCP23017 using GPIO0:7 on Port A and GPIO0:7 on Port B. Controlling on-board relays is easy: Set GPIO0:7 as Digital Outputs. Next, set the on/off status of GPIO0:7 to activate the corresponding relays. External 8-Channel GPIO port connections are controlled by the second MCP23017 of this controller, with the GPIO mapped to Port B. LEDs indicate the status of on-board relays. All of these operations are handled for you when using the drivers supplied in our GitHub repository (ControlEverythingCom). Induction suppression capacitors are strongly advised for inductive switching applications (anything that generates a magnetic field). Induction suppression capacitors will prolong the life of the relays and help prevent malfunctions when switching high voltages.
*Particle Photon not included.