Hi, so I'm trying to program a temperature controlled heater. The heater is attached with mains and is controlled by a solid state relay.
Initially it was just an on/off control at the set temp (target) but now I've tried to add code that switches the relay on and off in differing bursts to reduce the temperature of the heater in an attempt to reduce overshoot.
So for temperature being between 5 and 10 degrees Fahrenheit below the target, the heater switches on for 3 seconds and off for 3 seconds, repeating. For when it is below 10 degrees of the set point its 3 seconds on, 1 second off.
However when I run the code the relay is switching in really odd burst which I believe is a case of all 3 if statements about the temperature are being ignored when it is ran (The temp is below 10 degrees of the target). To test this I added LEDs to the two if statements which switch on. I also changed the if statements to something that should make it not run i.e target < 80 when the target is 90 or 3>2, but it still runs the statements and the LEDs light up.
When I remove two of the if statements for between 10 <x< 5 and 5 <x< 0 below the target, it appears to run correctly (at temp more than 10 below the target)
Please help me spot what is happening, also apologies for my poor form with the code, it's my first ever project using arduino.
#include <MillisTimer.h>
#include <OneWire.h>
#include <LiquidCrystal.h>
#include <DallasTemperature.h>
#define ONE_WIRE_BUS 7
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
float tempC = 0;
float tempF = 0;
float target = 90;
float ten = 10;
float five = 5;
float zero = 0;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
#define relay 9
const int upButtonPin = 13;
const int downButtonPin = 8;
bool targetChanged = false;
const long interval1 = 50;
const long interval2 = 1000;
const long interval3 = 3000;
const long interval4 = 6000;
unsigned long time_1a = 0;
unsigned long time_1b = 1000;
unsigned long time_2a = 0;
unsigned long time_2b = 3000;
unsigned long time_3a = 0;
unsigned long time_3b = 3000;
unsigned long time_4a = 0;
unsigned long time_4b = 0;
void setup() {
sensors.begin();
lcd.begin(16, 2);
lcd.clear();
pinMode(3, OUTPUT);
analogWrite(3, 0);
Serial.begin(9600);
pinMode(relay, OUTPUT);
digitalWrite(relay, LOW);
digitalWrite(10, LOW);
digitalWrite(6, LOW);
pinMode(upButtonPin, INPUT_PULLUP);
pinMode(downButtonPin, INPUT_PULLUP);
pinMode(10, OUTPUT);
pinMode(6, OUTPUT);
}
void loop() {
sensors.requestTemperatures();
tempC = sensors.getTempCByIndex(0);
tempF = sensors.toFahrenheit(tempC);
if (tempF + 10 < target) {
if (millis() >= time_1a + interval3 + interval2) {
time_1a += interval3 + interval2; //DELAY
digitalWrite(relay, HIGH); // HEAT OFF
}
if (millis() >= time_1b + interval3 + interval2) {
time_1b += interval3 + interval2;
digitalWrite(relay, LOW); //HEATING
}
}
if (tempF + 5 < target && target <= tempF + 10);
digitalWrite(10, HIGH); // BLUE
if (millis() >= time_2a + interval3 + interval3) {
time_2a += interval3 + interval3;
digitalWrite(relay, HIGH);
}
if (millis() >= time_2b + interval3 + interval3) {
time_2b += interval3 + interval3;
digitalWrite(relay, LOW);
}
if (tempF < target && target <= tempF + 5 ); {
digitalWrite(6, HIGH); //RED
if (millis() >= time_3a + interval4 + interval4) {
time_3a += interval4 + interval3;
digitalWrite(relay, HIGH);
}
if (millis() >= time_3b + interval3 + interval4) {
time_3b += interval3 + interval4;
digitalWrite(relay, LOW);
}
}
if (tempF >= target) {
digitalWrite(relay, HIGH);
}
checkUpButton();
checkDownButton();
if (targetChanged != true) {
Serial.println(tempC);
lcd.setCursor(0, 0);
lcd.print("Setpoint = ");
lcd.print(target);
lcd.setCursor(0, 1);
lcd.print("F: ");
lcd.print(tempF);
lcd.print(" degrees");
}
{
checkUpButton();
checkDownButton();
if (targetChanged == true)
{
lcd.clear();
lcd.setCursor(0, 0);
lcd.print("New setpoint =");
lcd.setCursor(0, 1);
lcd.print(target);
delay (1200);
lcd.clear();
}
}
}
void checkUpButton()
{
boolean buttonState = 0; // current state of the button
static boolean lastButtonState = 0; // previous state of the button
static unsigned long timer = 0;
unsigned long interval = 50; // check 20 times a second
if (millis() - timer >= interval)
{
timer = millis();
// read the pushbutton input pin:
buttonState = digitalRead(upButtonPin);
// compare the buttonState to its previous state
if (buttonState != lastButtonState)
{
// if the state has changed, increment the counter
if (buttonState == LOW)
{
// if the current state is LOW then the button went from off to on:
target++;
targetChanged = true;
}
// save the current state as the last state, for next time through the loop
lastButtonState = buttonState;
}
}
}
void checkDownButton()
{
boolean buttonState = 0; // current state of the button
static boolean lastButtonState = 0; // previous state of the button
static unsigned long timer = 0;
unsigned long interval = 50; // check 20 times a second
if (millis() - timer >= interval)
{
timer = millis();
// read the pushbutton input pin:
buttonState = digitalRead(downButtonPin);
// compare the buttonState to its previous state
if (buttonState != lastButtonState)
{
// if the state has changed, increment the counter
if (buttonState == LOW)
{
// if the current state is LOW then the button went from off to on:
target--;
targetChanged = true;
}
// save the current state as the last state, for next time through the loop
lastButtonState = buttonState;
}
}
}
