The CH34X family comprises widely used USB‑to‑serial chips manufactured by WCH (WinChipHead), commonly integrated into generic UNO R3, ESP8266, and ESP32 development boards.
Overview
The PCF8574 is an 8-bit I/O expander that allows for 8 digital inputs or outputs per device. It operates within a voltage range of 2.5V to 6V, making it compatible with both Arduino (5V) and ESP32 (3.3V) systems.
This IC communicates with the microcontroller via the I2C bus, which requires two pins: SDA (data) and SCL (clock). On the ESP32, SDA is on Pin 21 and SCL is on Pin 22. For the Arduino Uno R3, SDA is on Pin A4 and SCL is on Pin A5, or you can use the dedicated I2C ports located on the left side of the board.
You can connect up to 8 PCF8574 ICs to the same I2C bus, providing an additional 64 GPIOs per bus. Each PCF8574 must have a unique address, which can be set using the three jumpers on the board. Typically, the addresses range from 0x20 to 0x27.
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Documents
What’s in the Box
There are 3 pieces in the retail box.
The listing price is for
- 1 x PCF8574 I2C Digital IO Expansion Module
PCF8574 I2C Digital IO Expansion Module
$4.00
Tutorial
HC-05 Bluetooth Module and Arduino Beginner Tutorial
This is a basic example to get you start with HC-05 Bluetooth Module. Depending on your specific requirements and the functionality you want, you may need to expand and modify the sketch accordingly.
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