When developing smart home appliances, such as controlling motors or desk lamps, it's necessary to control the power on/off for high voltage or alternating current (AC). However, handling high-voltage directly by humans is dangerous. This is where relays come into play. The BMP75M131 is a single-channel relay module that can safely handle high-voltage with maximum load current 5A at 28VDC, 7A at 125VAC, and 5A at 240VAC.
A typical relay module uses an I/O signal to toggle its state. When there's a requirement to control eight relays, it will occupy eight I/O pins on the development board.
However, besides the I/O control mode, the BMP75M131 also provides networking mode. In networking mode, the development board can switch the states of each relay via I2C interface. Up to eight BMP75M131 relay modules can be cascaded concurrently, and only one module needs to be connected to the development board.
The operation mode can be selected by using the jumper on the BMP75M131. When cascading, the jumpers on each BMP75M131 module need to be disconnected (removed).
There is a BMCOM on the BMP75M131 designed for direct connection to the BMduino development board, such as BM53A367A. You can use the product with other development boards, such as Arduino UNO, as well.
Operation modes comparing
I/O control mode
Networking mode
Mode selection
(IO_mode Jumper)
Short-circuit the jumper.
Removed the jumper.
When cascading, jumpers on each module
need to be removed.
Cascading
Not cascadable.
Require individual controlled.
Cascadable (up to eight modules)
Only one module needs to be connected
to the development board.
Development control
Control relays through I/O pins.
Switch on relays in high level.
Issue commands through I2C interface
to control each cascaded relay.
