3

The essence of the program is to measure the temperature, and if the temperature is higher than 26 degrees, the servo rotates by 45 degrees, and if it's lower, it rotates by 179 degrees. However, a short circuit is occurring. At the moment of the first servo rotation, the temperature jumps to 40 degrees (the temperature is calculated from voltage), and after that, the servo continuously rotates back and forth because the temperature is fluctuating between 40 and 20 degrees. What could be the cause of this issue?

My code:

#include <Servo.h>
Servo myServo;
const int sensorPin = A0;
const float baselineTemp = 20.0;
int angle;
void setup() {
  myServo.attach(9);
  Serial.begin(9600);
}

void loop() {
  int sensorVal = analogRead(sensorPin);
  Serial.println("Sensor Value: ");
  Serial.print(sensorVal);
  float voltage = (sensorVal/1024.0) * 5.0;
  Serial.println("Volts:");
  Serial.print(voltage);
  Serial.println("Celcius:");
  float temperature = (voltage - .5) * 100;
  Serial.print(temperature);
  if (temperature < baselineTemp) {
    myServo.write(179);
  } else {
    myServo.write(45);
  }
  delay(800);
}

Output in terminal:

sensorVal: 149
 Volts:0.73
 Celcius:22.75
 sensorVal: 192
 Volts:0.94
 Celcius:43.75
 sensorVal: 154
 Volts:0.75
 Celcius:25.20
 sensorVal: 188
 Volts:0.92
 Celcius:41.80
 sensorVal: 150
 Volts:0.73
 Celcius:23.24
 sensorVal: 184
 Volts:0.90
 Celcius:39.84
 sensorVal: 151

Servo from right, tmp from left

6
  • 1
    Are all GNDs connected?
    – Sim Son
    Sep 11, 2023 at 19:40
  • 1
    What could be the cause of this issue? ... the servo
    – jsotola
    Sep 11, 2023 at 19:40
  • @SimSon I have just one GND and it's connected to "-"
    – Pain
    Sep 11, 2023 at 19:49
  • upvote for removing the picture and posting text
    – jsotola
    Sep 11, 2023 at 20:13
  • 1
    maybe the power supply voltage changes when the servo runs
    – jsotola
    Sep 11, 2023 at 23:37

1 Answer 1

1

You need to power the servo through a separate power supply. High power devices such as motors etc. should not be powered via the Arduino's regulator. That is surely affecting the analogRead() and therefore also the temperature reading as already noted by @jsotola.

Secondly, you need to add some hysteresis here to prevent continuous thrashing when the temperature is around the baseline:

if (temperature < baselineTemp) { myServo.write(179); } 
else { myServo.write(45); }

Maybe try something like :

if (temperature < baselineTemp - 1.0 ) { myServo.write(179); } 
elseif (temperature > baselineTemp + 1.0 ) { myServo.write(45); }

You could also try adding a capacitor across the power rails of the temperature sensor say 10uF very close to the sensor itself.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.