BoardPilotMCP23008 8-bit I/O expander (DIP-18) with ESP32
Supply 3.3-5 V
Bus I2C
I2C address
0x20 / 0x21 / 0x22 / 0x23 / 0x24 / 0x25 / 0x26 / 0x27
Pins and ESP32 wiring
| Pin | Role | ESP32 pin | Notes |
|---|---|---|---|
| SCL | I2C clock (SCL) | D22 | |
| SDA | I2C data (SDA) | D21 | |
| A2 | Not wired to the ESP32 | — | Address bit: tie to GND or VDD |
| A1 | Not wired to the ESP32 | — | |
| A0 | Not wired to the ESP32 | — | |
| RESET | Not wired to the ESP32 | — | Reset, active LOW. Tie to VDD |
| NC | Not wired to the ESP32 | — | Not connected |
| INT | Interrupt | D35 | Interrupt output, optional |
| VSS | Ground | GND | |
| GP0 | Not wired to the ESP32 | — | Expander I/O: to your LEDs or buttons, not to the ESP32 |
| GP1 | Not wired to the ESP32 | — | |
| GP2 | Not wired to the ESP32 | — | |
| GP3 | Not wired to the ESP32 | — | |
| GP4 | Not wired to the ESP32 | — | |
| GP5 | Not wired to the ESP32 | — | |
| GP6 | Not wired to the ESP32 | — | |
| GP7 | Not wired to the ESP32 | — | |
| VDD | Power | 3V3 |
Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.
Starter code (Arduino)
#include <Wire.h>
void setup() {
Serial.begin(115200);
Wire.begin(21, 22); // SDA = GPIO 21, SCL = GPIO 22
Wire.beginTransmission(0x20);
bool found = Wire.endTransmission() == 0;
Serial.println(found ? "MCP23008 8-bit I/O expander (DIP-18) found at 0x20" : "Not found: check power, GND and SDA/SCL");
}
void loop() {}Sources
- Microchip MCP23008 datasheet, Pinout (PDIP 18); address 0100 A2 A1 A0 (0x20 to 0x27); supply 1.8 to 5.5 V; needs external I2C pull-ups
Try it in 3D in BoardPilot
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Part data: CC BY 4.0, free to reuse with credit to BoardPilot.