Use integer math.

This feels like a good idea. ?

boil_kettle/boil_kettle.ino

@@ -19,7 +19,7 @@
 
 // Global variables.
 uint8_t KettleDuty = 0;
-double KettleTemp;
+uint8_t KettleTemp;
 uint8_t KettleSetpoint;
 modes KettleMode = OFF;
 
@@ -45,7 +45,6 @@ unsigned long lastRun = 0;
 // Return a character array to represent the
 // On/Off state of the kettle.
 char* ShowKettleState() {
-  char* LCD_Line;
   if (KettleMode == MANUAL) {
     return (char*)"Kettle:      Manual";
   } else if (KettleMode == AUTOMATIC) {
@@ -56,11 +55,13 @@ char* ShowKettleState() {
 }
 
 char* ShowKettleSetting() {
-  char* LCD_Line;
+  char LCD_Line[20];
   if (KettleMode == MANUAL) {
-    return sprintf(LCD_Line, "Kettle Power:   %03d%", KettleDuty);
+    sprintf(LCD_Line, "Kettle Power:   %03d%", KettleDuty / 10);
+    return LCD_Line;
   } else if (KettleMode == AUTOMATIC) {
-    return sprintf(LCD_Line, "Kettle Temp:    %03dF", KettleSetpoint);
+    sprintf(LCD_Line, "Kettle Temp:    %03dF", KettleSetpoint / 10);
+    return LCD_Line;
   } else {
     return (char*)"";
   }
@@ -77,10 +78,10 @@ void doEncoder()
 
   if (result) {
     uint8_t speed = rotary.speed();
-    speed >= 10 ? inc = 5 : inc = 1;
+    speed >= 10 ? inc = 50 : inc = 10;
   }
 
-  if (result == DIR_CW && KettleDuty < 100) {
+  if (result == DIR_CW && KettleDuty < 1000) {
     KettleDuty = (KettleDuty / inc) * inc + inc;
   } else if (result == DIR_CCW && KettleDuty > 0) {
     KettleDuty = (KettleDuty / inc) * inc - inc;
@@ -130,7 +131,7 @@ void setup() {
 
 void UpdateBoilKettle(){
   static uint8_t last_KettleDuty = 0;
-  static double last_KettleTemp = 0;
+  static uint8_t last_KettleTemp = 0;
 
   if (Enter.pressed()) {
 
@@ -157,7 +158,7 @@ void UpdateBoilKettle(){
 }
 
 void loop() {
-  KettleTemp = KettleThermo.readRTD();
+  KettleTemp = (uint8_t)(KettleThermo.readRTD() * 10);
   UpdateBoilKettle();
 
   unsigned long elapsedTime = (millis() - lastRun);

boil_kettle/slowPWM.h

@@ -20,8 +20,8 @@ class slowPWM {
       Serial.println("Setup PWM");
     }
 
-    byte compute(byte duty) {
+    byte compute(uint8_t duty) {
-      unsigned long onTime = (duty * period) / 100;
+      unsigned long onTime = (duty * period) / 1000;
       unsigned long offTime = period - onTime;
       unsigned long currentTime = millis();
 

boil_kettle/thermoControl.cpp

@@ -3,13 +3,13 @@
 #include <EEPROM.h>
 #include "thermoControl.h"
 
-thermoControl::thermoControl(double* input_temp, uint8_t* setpoint_temp, uint8_t* output_pwm, uint8_t* max_threshold, uint8_t* hysteresis) {
+thermoControl::thermoControl(uint8_t* input_temp, uint8_t* setpoint_temp, uint8_t* output_pwm, uint8_t* max_threshold, uint8_t* hysteresis) {
   output_pwm = output_pwm;
   input_temp = input_temp;
   setpoint_temp = setpoint_temp;
   
-  outMax = 100;
+  outMax = 1000;
-  outMin = 10;
+  outMin = 100;
   
   OpMode = OFF;
   SampleTime = 100;
@@ -22,11 +22,10 @@ bool thermoControl::Compute() {
   unsigned long timeChange = (now - lastTime);
 
   if(timeChange>=SampleTime && OpMode == AUTOMATIC) {
-    double output;
+    uint8_t output;
-    double input = *input_temp;
+    uint8_t error = *setpoint_temp - *input_temp;
-    double error = (double)*setpoint_temp - input;
 
-    if (error >= (double)*max_threshold) {
+    if (error >= *max_threshold) {
       output = outMax;
     } else if (error > *hysteresis) {
       output = 100 * error / *max_threshold;

boil_kettle/thermoControl.h

@@ -19,11 +19,11 @@ class thermoControl {
     unsigned long lastTime;
 
   public:
-    thermoControl(double*, uint8_t*, uint8_t*, uint8_t*, uint8_t*);
+    thermoControl(uint8_t*, uint8_t*, uint8_t*, uint8_t*, uint8_t*);
     bool Compute();
     void SetSampleTime(int);
     void SetPowerLimits(uint8_t, uint8_t);
-    void SetHysteresis(double);
+    void SetHysteresis(uint8_t);
     void SetThreshPWR(uint8_t);
     void SetMode(modes);
     modes GetMode();