HT16K33 8x8 LED matrix backpack (I2C) with ESP32

Supply 3.3-5 V Bus I2C I2C address 0x70 / 0x71 / 0x72 / 0x73 / 0x74 / 0x75 / 0x76 / 0x77

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
+	Power	3V3	Pin order varies between boards: match by the printed label. HT16K33 is rated 4.5 to 5.5 V. At 3V3 it usually works, dimmer
-	Ground	GND
D	I2C data (SDA)	D21	I2C data (SDA)
C	I2C clock (SCL)	D22	I2C clock (SCL)

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(0x70);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "HT16K33 8x8 LED matrix backpack (I2C) found at 0x70" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Sources

Holtek HT16K33 datasheet, Slave address 1110 A2 A1 A0; VDD 4.5 to 5.5 V
Adafruit LED Backpacks guide, 8x8 matrix backpack pinouts, address jumpers A0 to A2

Try it in 3D in BoardPilot

BoardPilot Part data (JSON)

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

HT16K33 8x8 LED matrix backpack (I2C) with ESP32

Pins and ESP32 wiring

Starter code (Arduino)

Sources

Try it in 3D in BoardPilot

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