Add PID.

There is no need for temperatures under 18 and above 89 degrees. Now it's easier to set the temp.

firmware/weckkubator/weckkubator.ino

@@ -2,28 +2,67 @@
 #include <LiquidCrystal_I2C.h>  // Support for PCF8574 --> LCD
 #include <OneWire.h>  // 1-Wiresupport for DS18B20
 #include <DallasTemperature.h>  // Easy reading of DS18B20
+#include <PID_v1.h>  // PID-Controller
 
 #define ONE_WIRE_BUS 10  // Enable 1-Wirebus on digital 10 (PB2 - Pin16)
+#define fan 8
+#define wecktopf 9
 
 LiquidCrystal_I2C lcd(0x3F,20,4);  // declare LCD
 OneWire oneWire(ONE_WIRE_BUS);  // declare 1-Wirebus
 DallasTemperature sensors(&oneWire);  // declare sensors 
 
-float tempset;
+// Define variables PID is connected to
-float watertemp;
+double pidset, watertemp, output;
+
+// PID adjustment
+double Kp=2, Ki=5, Kd=1;
+PID myPID(&watertemp, &output, &pidset, Kp, Ki, Kd, DIRECT);
+int WindowSize = 5000;
+unsigned long windowStartTime;
+
+// Temp adjustment
+int tempset;
 int poti;
 
+// time
+int onesecond = 1000;
+unsigned long previousMillis;
+
+
+// °C for LCD
+byte customChar[8] = {
+  0b01110,
+  0b01010,
+  0b01010,
+  0b01110,
+  0b00000,
+  0b00000,
+  0b00000,
+  0b00000
+};
+
 void setup() {
+  
   // Setup GPIO
-  pinMode(9, OUTPUT);  // Output "Wecktopf"
+  pinMode(wecktopf, OUTPUT);  // Output "Wecktopf"
-  pinMode(8, OUTPUT);  // Fan
+  pinMode(fan, OUTPUT);  // Fan
+  
   // Setup sensors
   sensors.begin();
+  
   // Setup I2C-LCD
   lcd.init();
   lcd.backlight();
   lcd.clear();
+  lcd.createChar(0, customChar);
   lcd.setCursor(1, 0);
+  
+  // Setup PID
+  windowStartTime = millis();
+  myPID.SetOutputLimits(0, WindowSize);  //tell the PID to range between 0 and the full window size
+  myPID.SetMode(AUTOMATIC);  //turn the PID on
+  
   // Greetings
   lcd.print("Weckkubator 0.0.1");
   delay(3000);
@@ -32,23 +71,34 @@ void setup() {
 }
 
 void loop() {
-  //
-  settemp();
-  readtemp();
-  lcdoutput();
-
-  delay(100);
-  
-  if (tempset >= watertemp) {
-    digitalWrite(9, HIGH);
 
+  // run pid
+  pid();
 
+  // update LCD
+  unsigned long currentMillis = millis();
+  if (currentMillis - previousMillis >= onesecond) {
+    settemp();
+    readtemp();
+    lcdoutput();
   }
-  else {
+}
-    digitalWrite(9, LOW);
 
+//------------------------------------------
+// PID-Controller
+void pid() {
+
+  myPID.Compute();
+
+  /************************************************
+   * turn the output pin on/off based on pid output
+   ************************************************/
+  if (millis() - windowStartTime > WindowSize)
+  { //time to shift the Relay Window
+    windowStartTime += WindowSize;
   }
-  
+  if (output < millis() - windowStartTime) digitalWrite(wecktopf, LOW);
+  else digitalWrite(wecktopf, HIGH);
 }
 
 //------------------------------------------
@@ -68,18 +118,32 @@ void readtemp() {
 void lcdoutput() {
   // Output temperatureset
   lcd.setCursor(0, 1);
-  lcd.print("s:");
+  lcd.print("set: ");
   lcd.print(tempset);
+  lcd.write((byte)0);
+  lcd.print("C");
 
   // Output watertemp
-  lcd.setCursor(9, 1);
+  lcd.setCursor(0, 2);
-  lcd.print("t:");
+  lcd.print("temp: ");
   lcd.print(watertemp);
+  lcd.write((byte)0);
+  lcd.print("C");
+  lcd.print("   ");
+
+  // output PID
+  lcd.setCursor (0, 3);
+  lcd.print("output: ");
+  lcd.print(output);
+  lcd.print("   ");
+
 }
 
+
 //------------------------------------------
 // Read Poti
 void settemp() {
   poti = analogRead(A3);
-  tempset = (poti*0.1);
+  tempset = (18+(poti*0.07));  // range between 18°C and 18+1024*0,07 (~89°C)
+  pidset = tempset;
 }