Intial working version

2 files changed, 151 insertions, 0 deletions

diff --git a/pid.py b/pid.py
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+++ b/pid.py
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+#The recipe gives simple implementation of a Discrete Proportional-Integral-Derivative (PID) controller. PID controller gives output value for error between desired reference input and measurement feedback to minimize error value.
+#More information: http://en.wikipedia.org/wiki/PID_controller
+#
+#cnr437@gmail.com
+#
+#######	Example	#########
+#
+#p=PID(3.0,0.4,1.2)
+#p.setPoint(5.0)
+#while True:
+#     pid = p.update(measurement_value)
+#
+#
+
+
+class PID:
+	"""
+	Discrete PID control
+	"""
+
+	def __init__(self, P=2.0, I=0.0, D=1.0, Derivator=0, Integrator=0, Integrator_max=500, Integrator_min=-500, Set_Point=0.0):
+
+		self.Kp=P
+		self.Ki=I
+		self.Kd=D
+		self.Derivator=Derivator
+		self.Integrator=Integrator
+		self.Integrator_max=Integrator_max
+		self.Integrator_min=Integrator_min
+
+		self.set_point=Set_Point
+		self.error=0.0
+
+	def update(self,current_value):
+		"""
+		Calculate PID output value for given reference input and feedback
+		"""
+
+		self.error = self.set_point - current_value
+
+		self.P_value = self.Kp * self.error
+		self.D_value = self.Kd * ( self.error - self.Derivator)
+		self.Derivator = self.error
+
+		self.Integrator = self.Integrator + self.error
+
+		if self.Integrator > self.Integrator_max:
+			self.Integrator = self.Integrator_max
+		elif self.Integrator < self.Integrator_min:
+			self.Integrator = self.Integrator_min
+
+		self.I_value = self.Integrator * self.Ki
+
+		PID = self.P_value + self.I_value + self.D_value
+
+		return PID
+
+	def setPoint(self,set_point):
+		"""
+		Initilize the setpoint of PID
+		"""
+		self.set_point = set_point
+		self.Integrator=0
+		self.Derivator=0
+
+	def setIntegrator(self, Integrator):
+		self.Integrator = Integrator
+
+	def setDerivator(self, Derivator):
+		self.Derivator = Derivator
+
+	def setKp(self,P):
+		self.Kp=P
+
+	def setKi(self,I):
+		self.Ki=I
+
+	def setKd(self,D):
+		self.Kd=D
+
+	def getPoint(self):
+		return self.set_point
+
+	def getError(self):
+		return self.error
+
+	def getIntegrator(self):
+		return self.Integrator
+
+	def getDerivator(self):
+		return self.Derivator
diff --git a/rpi-temp-control.py b/rpi-temp-control.py
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+++ b/rpi-temp-control.py
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+#!/usr/bin/env python3
+
+##
+# rpi-temp-control
+#
+#
+#
+# Matt Kohls
+
+import subprocess
+from gpiozero import Motor
+from pid import PID
+from time import sleep
+
+# Defaults
+TEMP_TARGET = float(47.0)
+FAN_PIN = 17   # Pin the fan control is tied to
+DUMMY_PIN = 18 # Any unused pin. Used to setup Motor from gpiozero
+MIN_FAN_SPEED = 80 / 100
+
+## Grabs Temperature of GPU/CPU
+#
+# @return temperature of GPU/CPU
+def grab_temp():
+    try:
+        file = open("/sys/class/thermal/thermal_zone0/temp", "r")
+        val = int(file.readline()) / 1000
+        file.close()
+        return val
+    except:
+        print("Error reading from thermal zone")
+        return 0
+
+# Initial loop setup
+ploop = PID(1, 1, .02, Integrator_max=100, Integrator_min=0, Set_Point=TEMP_TARGET)
+cycle = 1
+fan = Motor(FAN_PIN, DUMMY_PIN)
+fan.forward(cycle)
+last_duty_cycle = 0
+last_temp = 0
+
+while True:
+    sleep(1)
+    temp = grab_temp()
+    print(temp)
+    cycle_change = (ploop.update(temp)) * -1
+    cycle = (100 + int(cycle_change)) / 100 # Since fan.forward() wants a number between 0 and 1
+
+    if cycle <= .2:
+        cycle = 0
+    elif cycle > 1:
+        cycle = 1
+    elif cycle < MIN_FAN_SPEED:
+        cycle = MIN_FAN_SPEED
+
+    if cycle == 0:
+        fan.stop()
+    elif last_duty_cycle != cycle:
+        fan.forward(cycle)
+    last_duty_cycle = cycle
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