DS1307 real-time clock (Tiny RTC) with ESP32

Supply 5 V Bus I2C I2C address 0x68 / 0x50 Measures time

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
SQ	Not wired to the ESP32	—	Square wave output. Leave unconnected
DS	Not wired to the ESP32	—	Optional DS18B20 footprint. Leave unconnected
SCL	I2C clock (SCL)	D22	Pulled up to 5 V on the board: remove the pull-ups or use a level shifter
SDA	I2C data (SDA)	D21	Pulled up to 5 V on the board: remove the pull-ups or use a level shifter
VCC	Power	VIN	Needs 5 V: use VIN
GND	Ground	GND
BAT	Not wired to the ESP32	—	Battery voltage. Leave unconnected

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(0x68);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "DS1307 real-time clock (Tiny RTC) found at 0x68" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Sources

Maxim DS1307 datasheet, I2C address 0x68; supply 4.5 to 5.5 V
Microchip AT24C32 datasheet, EEPROM on the Tiny RTC board at 0x50

Try it in 3D in BoardPilot

BoardPilot Part data (JSON)

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

DS1307 real-time clock (Tiny RTC) with ESP32

Pins and ESP32 wiring

Starter code (Arduino)

Sources

Try it in 3D in BoardPilot

Related parts