El escenario
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.
Qué hay en este dibujo
Lee las decisiones que hay detrás.
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.