my_7segment_clock.py

#!/usr/bin/env python3

import time
import datetime
import signal
import sys

from Adafruit_LED_Backpack import SevenSegment

# To run:
#     sudo python3 ./my_7segment_clock.py
# ===========================================================================
# Clock Example
# ===========================================================================

# Set to 12 or 24 hour mode
HOUR_MODE_12_OR_24 = 12

# I2C address of display
LED_SEGMENT_I2C_ADDRESS = 0x70
# LED_SEGMENT_I2C_ADDRESS = 0x71

segment = SevenSegment.SevenSegment(address=LED_SEGMENT_I2C_ADDRESS)
# Initialize display. Must be called once before using the display.
segment.begin()
print("Using I2C address: 0x%02x" % (LED_SEGMENT_I2C_ADDRESS, ))
print("Press CTRL+C to exit")

io_error_count = 0


# systemd: time_display.service: State 'stop-sigterm' timed out. Killing.
def handler_stop_signals(signum, frame):
    segment.clear()
    segment.write_display()
    #time.sleep(4)
    # Raises SystemExit(0):
    sys.exit(0)


signal.signal(signal.SIGINT, handler_stop_signals)
signal.signal(signal.SIGTERM, handler_stop_signals)

# Continually update the time on a 4 char, 7-segment display
while (True):

    try:
        now = datetime.datetime.now()
        hour = now.hour
        minute = now.minute
        second = now.second

        segment.clear()

        if HOUR_MODE_12_OR_24 != 24:
            if hour > 12:  # handle 13 through 23
                hour = hour - 12
            if hour == 0:  # handle 0 (hour of midnight)
                hour = 12

        # Set hours
        if hour >= 10 or hour == 0:  # Tens
            segment.set_digit(0, int(hour / 10))
        else:
            segment.set_digit(0, ' ')

        segment.set_digit(1, hour % 10)  # Ones

        # Set minutes
        segment.set_digit(2, int(minute / 10))  # Tens
        segment.set_digit(3, minute % 10)  # Ones

        # Toggle colon
        segment.set_colon(second % 2)  # Toggle colon at 1Hz

        # Write the display buffer to the hardware.  This must be called to
        # update the actual display LEDs.
        segment.write_display()

        # Wait a quarter second (less than 1 second to prevent colon blinking)
        time.sleep(0.25)

    except KeyboardInterrupt:
        segment.clear()
        segment.write_display()
        sys.exit(0)

    # IOError: [Errno 121] Remote I/O error
    # - started happening frequently on stretch
    except IOError:
        io_error_count += 1
        print("Caught ", io_error_count, "IOErrors")
        time.sleep(2)