Add Arduino PID controller

brewapp/base/automatic/pid_arduino.py

@@ -0,0 +1,85 @@
+import time
+from brewapp import app, socketio
+from automaticlogic import *
+
+
+@brewautomatic()
+class PIDArduinoLogic(Automatic):
+
+    configparameter = [
+            {"name": "P", "value": 44},
+            {"name": "I", "value": 165},
+            {"name": "D", "value": 4},
+            {"name": "wait_time", "value": 5}]
+
+    def run(self):
+        sampleTime = 5
+        wait_time = float(self.config["wait_time"])
+        p = float(self.config["P"])
+        i = float(self.config["I"])
+        d = float(self.config["D"])
+        pid = PIDArduino(wait_time, p, i, d)
+
+        while self.isRunning():
+            heat_percent = pid.calc(self.getCurrentTemp(), self.getTargetTemp())
+            heating_time = sampleTime * heat_percent / 100
+            wait_time = sampleTime - heating_time
+            self.switchHeaterON()
+            socketio.sleep(heating_time)
+            self.switchHeaterOFF()
+            socketio.sleep(wait_time)
+
+
+# Based on Arduino PID Library
+# See https://github.com/br3ttb/Arduino-PID-Library
+class PIDArduino(object):
+
+    def __init__(self, kp, ki, kd, sampleTimeSec,
+                 outputMin=float('-inf'), outputMax=float('inf')):
+        if kp is None:
+            raise ValueError('kp must be specified')
+        if ki is None:
+            raise ValueError('ki must be specified')
+        if kd is None:
+            raise ValueError('kd must be specified')
+        if sampleTimeSec <= 0:
+            raise ValueError('sampleTimeSec must be greater than 0')
+        if outputMin >= outputMax:
+            raise ValueError('outputMin must be less than outputMax')
+
+        self._Kp = kp
+        self._Ki = ki * sampleTimeSec
+        self._Kd = kd / sampleTimeSec
+        self._sampleTime = sampleTimeSec * 1000
+        self._outputMin = outputMin
+        self._outputMax = outputMax
+        self._iTerm = 0
+        self._lastInput = 0
+        self._lastOutput = 0
+        self._lastCalc = 0
+
+    def calc(self, inputValue, setpoint):
+        now = PIDArduino._currentTimeMs()
+
+        if (now - self._lastCalc) < self._sampleTime:
+            return self._lastOutput
+
+        # Compute all the working error variables
+        error = setpoint - inputValue
+        self._iTerm += self._Ki * error
+        self._iTerm = min(self._iTerm, self._outputMax)
+        self._iTerm = max(self._iTerm, self._outputMin)
+        dInput = inputValue - self._lastInput
+
+        # Compute PID Output
+        self._lastOutput = self._Kp * error + self._iTerm - self._Kd * dInput
+        self._lastOutput = min(self._lastOutput, self._outputMax)
+        self._lastOutput = max(self._lastOutput, self._outputMin)
+
+        # Remember some variables for next time*/
+        self._lastInput = inputValue
+        self._lastCalc = now
+        return self._lastOutput
+
+    def _currentTimeMs():
+        return time.time() * 1000