情境
An AT89S52-based 16-relay control board using PCF8574 I2C I/O expanders and ULN2803 Darlington arrays to drive relays while minimizing MCU pin count.
這張圖裡有什麼
看懂背後的決策。
01
Used PCF8574 to convert I2C to 8-bit parallel output, reducing microcontroller I/O usage.
02
Integrated ULN2803 with common freewheeling diode connection to simplify relay coil protection.
Ideal for home automation, industrial control, and prototyping requiring high relay count with limited MCU pins.