LCD 20x4 with I2C backpack with ESP32

Supply 5 V Bus I2C I2C address 0x20 / 0x21 / 0x22 / 0x23 / 0x24 / 0x25 / 0x26 / 0x27 / 0x38 / 0x39 / 0x3A / 0x3B / 0x3C / 0x3D / 0x3E / 0x3F

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
GND	Ground	GND
VCC	Power	VIN	Needs 5 V for good contrast: use VIN
SDA	I2C data (SDA)	D21	The backpack pulls SDA up to 5 V. Usually works; a level shifter is safer
SCL	I2C clock (SCL)	D22	The backpack pulls SCL up to 5 V. Usually works; a level shifter is safer

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

This module is sold for 5 V. Its outputs may be 5 V: use a level shifter or a voltage divider on ESP32 inputs.

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 ? "LCD 20x4 with I2C backpack found at 0x20" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Sources

NXP PCF8574 / PCF8574A datasheet, Address 0x20 to 0x27 (PCF8574T) or 0x38 to 0x3F (PCF8574AT) via A0-A2; most backpacks ship as 0x27 or 0x3F
Hitachi HD44780U datasheet, Supply 5 V for standard character LCDs

Try it in 3D in BoardPilot

BoardPilot Part data (JSON)

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.

LCD 20x4 with I2C backpack with ESP32

Pins and ESP32 wiring

Starter code (Arduino)

Sources

Try it in 3D in BoardPilot

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