How to Use SparkFun gator:rtc: Examples, Pinouts, and Specs

The SparkFun gator:rtc is a specialized real-time clock (RTC) breakout board designed for seamless integration with the micro:bit platform. This component provides accurate timekeeping and timestamp functionality, which is essential for applications that require time-sensitive operations. Common use cases include data logging with time stamps, creating clocks or timers, and managing scheduled events in educational projects or hobbyist applications.

• IC Chip: Maxim Integrated DS3231 Real-Time Clock
• Voltage: 3.3V (supplied by the micro:bit)
• Battery Backup: CR1225 coin cell battery (not included)
• Time Accuracy: ±2ppm from 0°C to +40°C
• Communication: I2C interface

1. Connecting the gator:rtc: Use alligator clips to connect the 3V3 and GND pins on the gator:rtc to the corresponding 3.3V and GND pins on the micro:bit. Connect the SDA and SCL pins to pins 20 and 19 on the micro:bit, respectively.

2. Coding with MakeCode: Open the Microsoft MakeCode editor for micro:bit and include the gator:rtc package. Use the blocks provided by the package to set and get the time.

3. Using in a Circuit: When integrating the gator:rtc into a larger circuit, ensure that the I2C lines are not shared with other devices that might cause address conflicts.

• Battery Installation: Install a CR1225 coin cell battery to maintain timekeeping during power loss.
• Power Considerations: Ensure that the micro:bit is supplied with a stable 3.3V power source.
• I2C Pull-up Resistors: The gator:rtc has built-in pull-up resistors for the I2C lines. Do not add additional pull-up resistors to these lines.

• Time Not Accurate: Ensure that the CR1225 battery is installed correctly and has sufficient charge.
• Device Not Recognized: Check all connections, especially the I2C lines, for proper contact and continuity.
• Intermittent Functionality: Make sure there are no loose connections and that the micro:bit is properly powered.

• Q: Can the gator:rtc be used with other microcontrollers?

  • A: Yes, it can be used with any microcontroller that supports I2C communication, but additional code libraries may be required.

• Q: How long will the battery last?

  • A: The CR1225 battery can last for over a year, depending on the quality of the battery and the environmental conditions.

• Q: What is the purpose of the INT pin?

  • A: The INT pin can be used for alarm interrupts, which are not covered in this basic documentation.

For further assistance, consult the SparkFun gator:rtc datasheet or contact SparkFun support.

Below is an example code snippet for setting and reading the time on the gator:rtc using the micro:bit and MakeCode editor. This code assumes the inclusion of the gator:rtc package in the MakeCode editor.

// Initialize the gator:rtc and set the time to 12:00:00
gatorRTC.begin()
gatorRTC.setTime(12, 0, 0)

basic.forever(function () {
    // Read the current time from the gator:rtc
    let hours = gatorRTC.getHours()
    let minutes = gatorRTC.getMinutes()
    let seconds = gatorRTC.getSeconds()
    
    // Display the current time on the micro:bit's LED matrix
    basic.showString(hours + ":" + minutes + ":" + seconds)
})

Remember to wrap the code comments as needed to limit line length to 80 characters. This example provides a simple way to display the current time on the micro:bit's LED matrix.