MCP23017 16-bit I/O Expander

Operating Voltage

1.8 to 5.5 V

Standby Current Max

1 µA

Supply Current Max

1 mA

Interface

I2C

I2c Clock Speed Max

1.7 MHz

Operating Temperature Range

-40 to +125 °C

Package

28-pin QFN, 28-pin SOIC, 28-pin SPDIP, 28-pin SSOP

Number Of Io Pins

16

Output Current Per Pin Sink Max

25 mA

Output Current Per Pin Source Max

25 mA

I2c Bus Capacitive Loading Max

400 pF

Gpio Output Capacitive Loading Max

50 pF

I2c Address Pins

3

Community starter examples — minimal, unofficial, and provided to get you wiring fast. Verify against the manufacturer datasheet before relying on them.

// MCP23017 16-bit I2C I/O expander — community starter example
#include <Adafruit_MCP23X17.h>

Adafruit_MCP23X17 mcp;

void setup() {
  Serial.begin(115200);
  if (!mcp.begin_I2C(0x20)) { Serial.println("MCP23017 not found"); while (1) delay(10); }
  mcp.pinMode(0, OUTPUT);          // port A, pin 0
  mcp.pinMode(8, INPUT_PULLUP);    // port B, pin 0
}

void loop() {
  mcp.digitalWrite(0, HIGH);
  delay(300);
  mcp.digitalWrite(0, LOW);
  delay(300);
  Serial.println(mcp.digitalRead(8));
}

# MCP23017 I2C I/O expander (ESP32) — community starter example
# lib: mcauser/micropython-mcp23017 (mcp23017.py on the board)
from machine import Pin, I2C
from mcp23017 import MCP23017
import time

i2c = I2C(0, scl=Pin(22), sda=Pin(21))
mcp = MCP23017(i2c, 0x20)

mcp[0].output()        # GPA0 as output
while True:
    mcp[0].value(1); time.sleep(0.3)
    mcp[0].value(0); time.sleep(0.3)

• 16 extra GPIO over I2C
• Button matrices and LED banks with interrupts