Compatible with Raspberry Pi 3A+/B+/2B/3B/3B+/4B/Pi Zero/Pi Zero W, Arduino UNO R3 / MEGA 2560 / STM32/ESP32/ESP8266 The Relay Board gives your Pi board the ability to control high voltage/high current devices, and easily makes normal home appliances become intelligent. Can be accessed programmatically or directly by shell Up to 4 layers can be stacked.The 4 Channel Relay uses high-quality relay modules combined with the most popular microcontroller technology to communicate with the Pi board. You can use mulitiple relay modules stacked together to add many channels; The 4 Channel module is very fast, easy to install, and supports multi-language development, making it ideal for smart home projects. Description

4 Channel Relay Hat Board For Raspberry Pi is one of the "docker pi" module.
It has 4 channel relay that you can put it on your smart home project.
This four-channel relay uses high-quality relay modules combined with the most popular microcontroller technology to communicate with the Pi board.
You can use multiple modules stacked together for use.
You can stack up to four layers.
Switch the I2C address of the device through the DIP switch on the circuit board to ensure that the four-layer module gets different addresses, thus avoiding the problem of address duplication.
The module is very fast, easy to install, and supports multi-language development, making it ideal for smart home projects.
PS： The 4pin pin is a backup that supplies power to future products. You can ignore those pins. Please do not connect any device to that pins.

Features

Easy to use
4 channel relay
Support I2C protocol
Support for stacking
Support address switching by dial switch
Support multi-language programming
Support 3A 250V AC
Support 3A 30V DC
Support relay status light prompt

Package include

1x 4 Channel Relay Hat Board
4x M2.5x11+6 copper stick
8x M2.5x5 screws & nuts
1x Instructions

Wiki:

https://wiki.52pi.com/index.php/DockerPi_4_Channel_Relay_SKU:_EP-0099