kasun/RPI-GPIO-fan-temp-control-of-external-HDD-enclosure
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revised comments to be more comprehensive

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This commit is contained in:
Kasun Jayatilaka
2025-11-16 17:14:25 +01:00
parent d3c864b28d
commit 5e4bf4a8f9
1 changed files with 13 additions and 7 deletions
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18
fan_temp_sensor.py
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@@ -2,11 +2,11 @@ import glob
import time import time
import subprocess import subprocess
# Base directory for the 1-Wire devices # Base directory for the 1-Wire devices for the temperature sensor
base_dir = '/sys/bus/w1/devices/' base_dir = '/sys/bus/w1/devices/'
# Device folder for your specific sensor # Device folder for the specific sensor
device_folder = glob.glob(base_dir + '28-1f38831e64ff')[0] device_folder = glob.glob(base_dir + '28-1f38831e64ff')[0]
# Path to the w1_slave file # Path to the w1_slave file containing the actual temperature reading
device_file = device_folder + '/w1_slave' device_file = device_folder + '/w1_slave'
def read_temp_raw(): def read_temp_raw():
@@ -18,14 +18,15 @@ def read_temp_raw():
def read_temp(): def read_temp():
"""Parse the raw temperature data and return the temperature in Celsius.""" """Parse the raw temperature data and return the temperature in Celsius."""
lines = read_temp_raw() lines = read_temp_raw()
# Wait until the sensor output is valid # Keep checking until the sensor says its reading is valid (ends with 'YES')
while lines[0].strip()[-3:] != 'YES': while lines[0].strip()[-3:] != 'YES':
time.sleep(0.2) time.sleep(0.2)
lines = read_temp_raw() lines = read_temp_raw()
# Find the temperature value in the second line # Find the temperature value in the second line 't='
equals_pos = lines[1].find('t=') equals_pos = lines[1].find('t=')
if equals_pos != -1: if equals_pos != -1:
temp_string = lines[1][equals_pos + 2:] temp_string = lines[1][equals_pos + 2:]
# The sensor gives temp in thousandths of a degree, so divide by 1000
temp_c = float(temp_string) / 1000.0 temp_c = float(temp_string) / 1000.0
return temp_c return temp_c
@@ -35,14 +36,19 @@ def execute_command(command):
# Main loop to read and print the temperature # Main loop to read and print the temperature
if __name__ == "__main__": if __name__ == "__main__":
execute_command('pinctrl set 18 op') # First, set it as output # Set up pin 18 to control the fan relay
execute_command('pinctrl set 18 op')
while True: while True:
# Get the current temperature
temp_c = read_temp() temp_c = read_temp()
print(f"Temperature: {temp_c:.2f} °C") print(f"Temperature: {temp_c:.2f} °C")
# Turn fan ON if temperature is 46°C or higher by setting pin to low
if temp_c >= 46: if temp_c >= 46:
execute_command('pinctrl set 18 dl') execute_command('pinctrl set 18 dl')
# Turn fan OFF if temperature drops to 40°C or lower by setting pin to high
elif temp_c <= 40: elif temp_c <= 40:
execute_command('pinctrl set 18 dh') execute_command('pinctrl set 18 dh')
# Wait 1 second before checking temperature again
time.sleep(1) time.sleep(1)