The main loop simply checks the position of the switch and then either displays the temperature or the time.
# SPDX-FileCopyrightText: 2019 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT
import glob
import time
import datetime
from adafruit_ht16k33 import segments
import board
import busio
import digitalio
switch_pin = digitalio.DigitalInOut(board.D18)
switch_pin.direction = digitalio.Direction.INPUT
switch_pin.pull = digitalio.Pull.UP
# Create the I2C interface.
i2c = busio.I2C(board.SCL, board.SDA)
# Create the LED segment class.
# This creates a 7 segment 4 character display:
display = segments.Seg7x4(i2c)
base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')[0]
device_file = device_folder + '/w1_slave'
def read_temp_raw():
f = open(device_file, 'r')
lines = f.readlines()
f.close()
return lines
def read_temp():
lines = read_temp_raw()
while lines[0].strip()[-3:] != 'YES':
time.sleep(0.2)
lines = read_temp_raw()
equals_pos = lines[1].find('t=')
if equals_pos != -1:
temp_string = lines[1][equals_pos+2:]
temp_c = float(temp_string) / 1000.0
temp_f = temp_c * 9.0 / 5.0 + 32.0
return temp_c, temp_f
def display_temp():
temp = read_temp()[1] # F
# temp = read_temp()[0] # C
display.print(int(temp))
def display_time():
now = datetime.datetime.now()
hour = now.hour
minute = now.minute
second = now.second
clock = int('%i%i' % (hour,minute)) # concat hour + minute
display.print(clock)
# Toggle colon when displaying time
if second % 2:
display.print(':') # Enable colon every other second
else:
display.print(';') # Turn off colon
display.fill(0)
while True:
if not switch_pin.value:
display_temp()
else:
display_time()
time.sleep(0.5)
We can easily copy this code onto our Pi's home directory using the 'wget' command and run it using the following python syntax.
cd wget https://raw.githubusercontent.com/adafruit/Adafruit_Learning_System_Guides/master/Large-Pi-Based-Thermometer-Clock/thermo_clock.py
The thermo_clock.py script will not output anything when run, but what you should see is the time or temperature on the large 7-segment display. Using the slide switch should switch modes between time and temperature.
python3 ./thermo_clock.py
The temperature display can easily be changed from displaying degrees F to degrees C by swapping comment line in the code.
temp = int(read_temp()[1]) # F # temp = int(read_temp()[0]) # C
To swap, just move the # in front of the line that does not apply.
Page last edited January 21, 2025
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