Full Running Clock Using the TM1637

I'll create a detailed example of a running clock using the TM1637 display. This builds on some of the concepts shown in the clock-driver.py file you shared, but simplified for the TM1637.

import tm1637
from machine import Pin, RTC
from utime import sleep, localtime

# Initialize the display
tm = tm1637.TM1637(clk=Pin(0), dio=Pin(1))

# Initialize the RTC (Real Time Clock)
rtc = RTC()

def set_initial_time():
    """
    Set an initial time if RTC isn't configured.
    In a real project, you'd sync this with a time server or user input.
    """
    # Format: (year, month, day, weekday, hours, minutes, seconds, subseconds)
    rtc.datetime((2024, 12, 28, 5, 12, 0, 0, 0))

def format_time(hours, minutes):
    """
    Convert 24-hour time to 12-hour format
    Returns hours and whether it's PM
    """
    is_pm = hours >= 12
    if hours > 12:
        hours -= 12
    elif hours == 0:
        hours = 12
    return hours, is_pm

def run_clock():
    # Set initial brightness (0-7)
    tm.brightness(2)

    # Track colon state for blinking
    colon_on = True

    while True:
        # Get current time from RTC
        year, month, day, weekday, hours, minutes, seconds, _ = rtc.datetime()

        # Convert to 12-hour format
        display_hours, is_pm = format_time(hours, minutes)

        # Toggle colon every second
        if seconds != prev_seconds:
            colon_on = not colon_on
            prev_seconds = seconds

        # Display the time
        tm.numbers(display_hours, minutes, colon=colon_on)

        # Brief pause to prevent display flicker
        sleep(0.1)

if __name__ == '__main__':
    set_initial_time()  # Only needed if RTC isn't set
    print("Starting clock...")
    run_clock()

Core Concepts

Let's break down the key concepts students need to understand:

1. Real-Time Clock (RTC)

• The RTC is a hardware component that keeps track of time
• It continues running even when the microcontroller is reset
• Time is stored as a tuple: (year, month, day, weekday, hours, minutes, seconds, subseconds)
• Students should understand why RTCs are important for accurate timekeeping

2. Time Formats

• 24-hour vs 12-hour time conversion
• Why we need to handle special cases (midnight = 0 hours → 12, noon = 12 stays 12)
• The concept of AM/PM

3. Display Multiplexing

• How LED displays show multiple digits (though the TM1637 handles this internally)
• Why we need a brief sleep to prevent display flicker
• How brightness control works with PWM (Pulse Width Modulation)

4. State Management

• Tracking the colon state for blinking
• Maintaining previous second value to detect changes
• Why we use global variables in this context

5. Program Structure

• Main loop design
• Function organization
• Error handling (not shown but important in real applications)

Common challenges

Here are some challenges students might encounter:

1. Time Drift

• The RTC might drift slightly over time
• In real applications, you'd want to sync with an NTP server periodically

2. Power Management

• Display brightness affects power consumption
• Consider dimming display in low light conditions
• Think about battery life in portable applications

3. User Interface

• Adding buttons to set the time
• Handling time zone changes
• Adding features like alarms or timers

Extensions

Here are some additional projects that students could try:

1. Add a temperature display that alternates with the time
2. Implement automatic brightness control using a light sensor
3. Add alarm functionality with a buzzer
4. Create a menu system for setting the time
5. Add a battery backup system

For reference, this code builds on the concepts shown in our clock-driver.py file, but simplifies the implementation thanks to the TM1637's built-in controller.