ESP32 and PCF8575 I/O expander example

This 16-bit I/O expander for the two-line bidirectional bus (I²C) is designed for 2.5-V to 5.5-V V_CC operation.

The PCF8575 device provides general-purpose remote I/O expansion for most microcontroller families by way of the I²C interface [serial clock (SCL), serial data (SDA)].

The device features a 16-bit quasi-bidirectional input/output (I/O) port (P07–P00, P17–P10), including latched outputs with high-current drive capability for directly driving LEDs.

Each quasi-bidirectional I/O can be used as an input or output without the use of a data-direction control signal. At power on, the I/Os are high. In this mode, only a current source to V_CC is active.

Features

Connection

This example shows only one LED

esp32 and PCF8575

Parts List

Name	Link
ESP32		Aliexpress link Amazon Ebay
PCF8575		Aliexpress link Ebay link Amazon Link
Connecting cables		Aliexpress link Amazon Ebay

Code example

Output – switch LED on and off

#include <Wire.h>

// Set I2C address
int address = 0x20;

void setup()
{ 
  Wire.begin();
  // Set all ports as output
  pf575_write(word(B11111111,B11111111));
} 

void loop()
{
  // Set port P0 on
  pf575_write(word(B00000000,B00000001));
  delay(1000);
  // Set port P0 off
  pf575_write(word(B00000000,B00000000));
  delay(1000);
} 

// Function for writing two Bytes to the I2C expander device
void pf575_write(uint16_t data) 
{
  Wire.beginTransmission(address);
  Wire.write(lowByte(data));
  Wire.write(highByte(data));
  Wire.endTransmission();
}