How to Use TINY RTC: Examples, Pinouts, and Specs

The TINY RTC is a compact real-time clock (RTC) module designed to keep track of the current time and date. It is widely used in microcontroller projects to maintain accurate timekeeping, even when the main power supply is disconnected. This is achieved through the use of a backup battery, which ensures continuous operation. The module is based on the DS1307 RTC chip and is commonly paired with microcontrollers like Arduino, Raspberry Pi, and others.

• Time-stamping data in data logging projects
• Scheduling tasks in automation systems
• Alarm clocks and timers
• Maintaining time in power-sensitive systems
• Real-time event tracking in IoT devices

The TINY RTC module is built around the DS1307 RTC chip and includes additional components like a backup battery and pull-up resistors for I2C communication. Below are the key technical details:

• Chipset: DS1307 Real-Time Clock IC
• Communication Protocol: I2C (Inter-Integrated Circuit)
• Operating Voltage: 5V DC
• Backup Battery: CR2032 coin cell (3V)
• Timekeeping Accuracy: ±2 seconds/day (typical)
• Time Format: 24-hour or 12-hour with AM/PM
• Temperature Range: 0°C to +70°C (operating)
• Memory: 56 bytes of non-volatile RAM for user data

The TINY RTC module typically has a 4-pin interface for I2C communication. Below is the pinout:

1. Connect the Module:

   • Connect the VCC pin to the 5V output of your microcontroller.
   • Connect the GND pin to the ground of your microcontroller.
   • Connect the SDA pin to the I2C data line of your microcontroller.
   • Connect the SCL pin to the I2C clock line of your microcontroller.

2. Install the Backup Battery:

   • Insert a CR2032 coin cell battery into the battery holder on the module. This ensures the RTC continues to keep time even when the main power is off.

3. Include the Required Libraries:

   • For Arduino, use the RTClib library, which provides easy-to-use functions for the DS1307.

4. Write and Upload Code:

   • Use the example code below to initialize the RTC and read the current time and date.

#include <Wire.h>
#include <RTClib.h>

// Create an RTC object
RTC_DS1307 rtc;

void setup() {
  Serial.begin(9600); // Initialize serial communication
  Wire.begin();       // Initialize I2C communication

  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC. Check connections!");
    while (1); // Halt execution if RTC is not found
  }

  if (!rtc.isrunning()) {
    Serial.println("RTC is not running. Setting the time...");
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    // Sets the RTC to the date & time of compilation
  }
}

void loop() {
  DateTime now = rtc.now(); // Get the current time and date

  // Print the current time and date to the Serial Monitor
  Serial.print(now.year(), DEC);
  Serial.print('/');
  Serial.print(now.month(), DEC);
  Serial.print('/');
  Serial.print(now.day(), DEC);
  Serial.print(" ");
  Serial.print(now.hour(), DEC);
  Serial.print(':');
  Serial.print(now.minute(), DEC);
  Serial.print(':');
  Serial.print(now.second(), DEC);
  Serial.println();

  delay(1000); // Wait for 1 second before updating
}

• Ensure the backup battery is installed correctly to maintain timekeeping during power loss.
• Avoid shorting the battery terminals, as this can damage the module.
• Use pull-up resistors on the I2C lines if they are not already included on the module.
• Verify the I2C address of the module (default is 0x68) if using multiple I2C devices.

1. RTC Not Detected:

   • Cause: Loose or incorrect wiring.
   • Solution: Double-check the connections, especially the SDA and SCL lines.

2. Incorrect Time or Date:

   • Cause: RTC not initialized or backup battery is depleted.
   • Solution: Use the rtc.adjust() function to set the correct time and replace the battery if necessary.

3. I2C Communication Errors:

   • Cause: Address conflict or missing pull-up resistors.
   • Solution: Ensure the I2C address is correct and add pull-up resistors if needed.

4. RTC Stops Keeping Time After Power Loss:

   • Cause: Backup battery is missing or dead.
   • Solution: Install a new CR2032 battery.

Q: Can the TINY RTC module work with 3.3V microcontrollers?
A: The DS1307 chip requires a 5V power supply. Use a level shifter for I2C lines if interfacing with a 3.3V microcontroller.

Q: How long does the backup battery last?
A: A typical CR2032 battery can last for several years, depending on usage and environmental conditions.

Q: Can I use the TINY RTC module to store custom data?
A: Yes, the DS1307 includes 56 bytes of non-volatile RAM that can be used to store user data.

Q: What is the default I2C address of the TINY RTC module?
A: The default I2C address is 0x68.