PCF8574 is an IO port expansion module that uses the I2C protocol. It has three address pins and can allocate up to 8 addresses simultaneously. The board includes 8-bit bidirectional IO ports (P0-P7), each of which can be separately assigned as an input or output without the need for data direction control signals. When powered on, all IO levels default to high level
Supply voltage: 3.3V/5V
Communication interface: I2C interface, 8-bit parallel port
Interface type: pin or socket
Interrupt output: connected to MCU interrupt pin, low level is valid
I2C Address Setting Instructions
The default I2C address of the module is 0x20
The I2C address can be set to 8 different addresses through A0-A2, as shown in the figure
All jumpers are set on the “-” side, meaning LOW is a low level
The “+” side is HIGH, which is a high level
The range of addresses from 0x20 to 0x27 is shown in the table below, which means that one development board can simultaneously connect 8 PCF8574 modules
