Update fancontrol.py

fancontrol.py

@@ -1,55 +1,78 @@
 #!/usr/bin/env python3
 
-import subprocess
 import time
 
 from gpiozero import OutputDevice
 
-
-ON_THRESHOLD = 65  # (degrees Celsius) Fan kicks on at this temperature.
-OFF_THRESHOLD = 55  # (degress Celsius) Fan shuts off at this temperature.
-SLEEP_INTERVAL = 5  # (seconds) How often we check the core temperature.
-GPIO_PIN = 17  # Which GPIO pin you're using to control the fan.
-
+MAX_THRESHOLD = 60.0 # (degrees Celsius) Fan kicks on at full speed at this temperature.
+MIN_THRESHOLD = 50.0 # (degress Celsius) Fan kicks on at minimum speed at this temperature.
+SLEEP_INTERVAL = 1.0 # (miliseconds) How long one tick last
+GPIO_PIN = 17 # Which GPIO pin you're using to control the fan.
+MIN_TICKS = 100 # Number of min ticks in cycle
+MAX_TICKS = 1000 # Number of max ticks in cycle
+FAN_ON = 1
+FAN_OFF = 0
 
 def get_temp():
     """Get the core temperature.
-
-    Run a shell script to get the core temp and parse the output.
-
-    Raises:
-        RuntimeError: if response cannot be parsed.
-
+    Read file from /sys to get CPU temp in temp in C *1000
     Returns:
-        float: The core temperature in degrees Celsius.
+        int: The core temperature in thousanths of degrees Celsius.
     """
-    output = subprocess.run(['vcgencmd', 'measure_temp'], capture_output=True)
-    temp_str = output.stdout.decode()
-    try:
-        return float(temp_str.split('=')[1].split('\'')[0])
-    except (IndexError, ValueError):
-        raise RuntimeError('Could not parse temperature output.')
+    with open('/sys/class/thermal/thermal_zone0/temp') as f:
+        temp_str = f.read()
 
+    try:
+        return int(temp_str) / 1000
+    except (IndexError, ValueError,) as e:
+        raise RuntimeError('Could not parse temperature output.') from e
+
+def normalize_temp(temp):
+    temp = ((float(temp) - MIN_THRESHOLD) / (MAX_THRESHOLD - MIN_THRESHOLD))
+    if temp < 0.0:
+        temp = 0.0
+    if temp > 1.0:
+        temp = 1.0
+    return float(temp)
+
+def count_fire_tick(temp):
+    temp = int((MAX_TICKS / MIN_TICKS) - (MAX_TICKS / MIN_TICKS) * float(temp))
+    if temp <= 0:
+        temp = 1
+    return int(temp)
+
+def fan_command(command, fan):
+    if command == FAN_ON and not fan.value:
+        fan.on()
+    if command == FAN_OFF and fan.value:
+        fan.off()
+
+def run_cycle(fire_tick, fan):
+    i = 0
+    while i < MAX_TICKS:
+        i += 1
+        if (i % fire_tick) == 0:
+            fan_command(FAN_ON, fan)
+        time.sleep(SLEEP_INTERVAL / 1000.0)
+        if (i % fire_tick) != 0:
+            fan_command(FAN_OFF, fan)
 
 if __name__ == '__main__':
-    # Validate the on and off thresholds
-    if OFF_THRESHOLD >= ON_THRESHOLD:
-        raise RuntimeError('OFF_THRESHOLD must be less than ON_THRESHOLD')
+    # Validate the min and max thresholds
+    if MIN_THRESHOLD >= MAX_THRESHOLD:
+        raise RuntimeError('MIN_THRESHOLD must be less than MAX_THRESHOLD')
+
+    # Validate the min and max ticks
+    if MIN_TICKS >= MAX_TICKS:
+        raise RuntimeError('MIN_TICKS must be less than MAX_TICKS')
 
     fan = OutputDevice(GPIO_PIN)
 
     while True:
         temp = get_temp()
 
-        # Start the fan if the temperature has reached the limit and the fan
-        # isn't already running.
-        # NOTE: `fan.value` returns 1 for "on" and 0 for "off"
-        if temp > ON_THRESHOLD and not fan.value:
-            fan.on()
+        temp = normalize_temp(temp)
 
-        # Stop the fan if the fan is running and the temperature has dropped
-        # to 10 degrees below the limit.
-        elif fan.value and temp < OFF_THRESHOLD:
-            fan.off()
+        temp = count_fire_tick(temp)
 
-        time.sleep(SLEEP_INTERVAL)
+        run_cycle(temp, fan)