I'm traing to set up a temperature controlled fan. Got it from a video.
Link to video:
So I put everything together and now have a few problems.
The base temperature is around -2,6°C (27.27°F) and I dont know why or how to change it.
Also the reading goes down when I apply heat.
I'm pretty sure I got everything connected as instructed but I just don't know what to do about the problems. I'm not a programmer. To be honest, I can kinda read the code but couldn't write one myself.
Code:
//CONFIG =====================================================================================
#define aref_voltage 3.3 // we tie 3.3V to ARef and measure it with a multimeter!
//TMP36 Pin Variables
int tempPin = 0; // TMP36 Center lead to Analog Pin [A1-A7] (Elegoo Nano v.3)
int tempReading; // the analog reading from the sensor
//Relay Pin Variable
int relayPin = 2; // Relay Singnal lead to Digital Pin [D2-D12] (Elegoo Nano v.3)
//Tempurature Range
// Its good to provide a buffer for efficiency, if the temp bounces from 79-81 constantly
// it will turn on and off the fan constantly. So set a minimum temperature that the fan
// can cool the are too before it starts checking for max temperature.
float maxTemperature = 40.00; // The Max Temperature allowed
float minTemperature = 35.00; // The Min Temperature allowed
//=============================================================================================
void setup() {
// We'll send debugging information via the Serial monitor
Serial.begin(9600);
// If you want to set the aref to something other than 5v
analogReference(EXTERNAL); // Feed the 3.3v cable back into the AREF pin
// Pin Setup/Register
pinMode(relayPin, OUTPUT);
}
void loop() {
// put your main code here, to run repeatedly:
float temperature = getTemperature();
if (temperature >= maxTemperature) {
powerOnRelay();
} else if (temperature <= minTemperature) {
powerOffRelay();
}
delay(1000); // Check tempertature every second
}
void powerOnRelay() {
digitalWrite(relayPin, HIGH);
Serial.println("Relay On");
}
void powerOffRelay() {
digitalWrite(relayPin, LOW);
Serial.println("Relay Off");
}
float getTemperature() {
tempReading = analogRead(tempPin);
float voltage = tempReading * aref_voltage;
voltage /= 1024.0;
// now print out the temperature
float temperatureC = (voltage - 0.5) * 100 ; //converting from 10 mv per degree wit 500 mV offset to degrees ((volatge - 500mV) times 100)
Serial.print(temperatureC); Serial.println(" degrees C"); // For debuging purpouses
// now convert to Fahrenheight
float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;
// Serial.print(temperatureF); Serial.println(" degrees F");
// Choose which tempurature you would like to use.
//return temperatureF; //Fahrenheight
return temperatureC; // Celcius
}
Get rid of the REF voltage stuff, you dont need it. That is whats messing your program up. Here is the altered code i did for you. I have tested this on an Arduino Uno and it works.
Make sure your Temp Sensor is connected correctly. Power pin to 5v, ground to ground and middle pin to A0.
//CONFIG =====================================================================================
//TMP36 Pin Variables
int tempPin = A0; // TMP36 Center lead to Analog Pin [A1-A7] (Elegoo Nano v.3) // the analog reading from the sensor
//Relay Pin Variable
int relayPin = 2; // Relay Singnal lead to Digital Pin [D2-D12] (Elegoo Nano v.3)
//Tempurature Range
// Its good to provide a buffer for efficiency, if the temp bounces from 79-81 constantly
// it will turn on and off the fan constantly. So set a minimum temperature that the fan
// can cool the are too before it starts checking for max temperature.
float maxTemperature = 40.00; // The Max Temperature allowed
float minTemperature = 35.00; // The Min Temperature allowed
//=============================================================================================
void setup() {
// We'll send debugging information via the Serial monitor
Serial.begin(9600);
// If you want to set the aref to something other than 5v
//analogReference(EXTERNAL); // Feed the 3.3v cable back into the AREF pin
// Pin Setup/Register
pinMode(relayPin, OUTPUT);
}
void loop() {
// put your main code here, to run repeatedly:
float temperature = getTemperature();
if (temperature >= maxTemperature) {
powerOnRelay();
} else if (temperature <= minTemperature) {
powerOffRelay();
}
delay(1000); // Check tempertature every second
}
void powerOnRelay() {
digitalWrite(relayPin, HIGH);
Serial.println("Relay On");
}
void powerOffRelay() {
digitalWrite(relayPin, LOW);
Serial.println("Relay Off");
}
float getTemperature() {
int tempReading = analogRead(tempPin);
float voltage = tempReading * 5.0;
voltage /= 1024.0;
// now print out the temperature
float temperatureC = (voltage -.5) * 100; //converting from 10 mv per degree wit 500 mV offset to degrees ((volatge - 500mV) times 100)
Serial.print(temperatureC);
Serial.println(" degrees C"); // For debuging purpouses
// now convert to Fahrenheight
//float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;
// Serial.print(temperatureF); Serial.println(" degrees F");
// Choose which tempurature you would like to use.
//return temperatureF; //Fahrenheight
return temperatureC; // Celcius
}
Thats so nice of you. I tried it. Disconnected the relay and reconnected the temp sensor on 5V, GRD and A1. The Offset went from -2.6 to +3.71°C (probably because of the change from 3.3 to 5 V). And when I heat up the sensor, the numbers go down still. Must be hardware a this point. Will try another TMP36 and see what happens.
Yes, you must have something connected incorrectly. When i get home tonight ill set up my uno again and test everything. When i simulate it on tinkercad everything works correctly.
