2 relays are always turned on. Help with code!

Projects Programming
1

Can someone help me with this code?
Two relays are always turned on if the other two are off. I use the 4 Relay Module.
I MADE THE CIRCUIT (ON IMAGE) IN 123 CIRCUITS JUST TO YOU GUYS AN IDEA HOW I MADE ALL CONNECTIONS

I have attached the .ino file

ARDUINO SOLAR TRACKER.png
ARDUINO SOLAR TRACKER.png935×832 138 KB

Arduino_5V_Relay_Solar_Tracker.ino (1.43 KB)

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Now I uploaded your code, but it does the same mine does.
2 relays are always turned on when both LDR´s get the same amount of light, but both should be turned off.
And if one LDR gets shadow, relays 1 & 2 turn off and 3 & 4 turn on. But if the second LDR recieves shadow, 1 & 2 turn on and 3 & 4 off, but 1 & 2 stay on if the second LDR recieves sunlight again.

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I have modified the explanation, because I had made an error.

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If your 4 Relay module is like the one shown below, then it definitely needs a separate power supply. Shown are connections that would take advantage of the built-in opto isolation feature.

EDIT: What are the 10K resistors for?

EDIT: Test Code

Note: Code for 8-relay module would also work with 4 relay module. Easily modified to sequence through 4 relays only.

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Thanks! I´ll try it.

My dad had already talked to another guy about it and he had told my dad that maybe that would solve the problem. But I don´t think that´s very true.

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Elizandro:
Now I uploaded your code, but it does the same mine does.
2 relays are always turned on when both LDR´s get the same amount of light, but both should be turned off.
And if one LDR gets shadow, relays 1 & 2 turn off and 3 & 4 turn on. But if the second LDR recieves shadow, 1 & 2 turn on and 3 & 4 off, but 1 & 2 stay on if the second LDR recieves sunlight again.

Oh, right. Dude, think. Where in this code doe it deal with the condition where both relays are getting the same amount of light? That's right - nowhere. If you want that behaviour, then you have to out it in:

const byte sens1 = A0;
const byte sens2 = A1;

void setup()
{
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  digitalWrite(11, HIGH);
  digitalWrite(12, HIGH);
  digitalWrite(10, HIGH);
  digitalWrite(9, HIGH);
}

void loop()
{
  int val1 = analogRead(sens1);
  int val2 = analogRead(sens2);

  if (val1 > val2)
  {
    digitalWrite(9, LOW);
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(12, LOW);
  }
  else if (val1 < val2)
  {
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
    digitalWrite(12, HIGH);
  }
  else {
    digitalWrite(9, LOW);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
    digitalWrite(12, LOW);
  }
}

The problem with this code, however, is that it will only turn off the relays if both inputs A0 and A1 are exactly the same. This probably isn't helpful, because its 1 in 1024.

So what you need is some slop:

// not sure how much slop you need - you will have to experiment
const int SLOP = 10; 

void loop()
{
  int val1 = analogRead(sens1);
  int val2 = analogRead(sens2);

  if (val1 - val2 > SLOP)
  {
    digitalWrite(9, LOW);
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(12, LOW);
  }
  else if (val1 - val2 < -SLOP)
  {
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
    digitalWrite(12, HIGH);
  }
  else {
    digitalWrite(9, LOW);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
    digitalWrite(12, LOW);
  }
}

Your other problem is hysteresis. If one sensor is juuuust SLOP more than the other, your relays will chatter at that boundary. To fix this, once the relay has gone one way, we make it a little "sticky", a little more likely to stay in that position. This means that we don't need that slop factor.

// not sure how much hysteresis you need - you will have to experiment
const int HYSTERESIS = 10;

int hysteresis = 0;

void loop()
{
  int val1 = analogRead(sens1);
  int val2 = analogRead(sens2);

  if (val1 - val2 + hysteresis > 0 )
  {
    digitalWrite(9, LOW);
    digitalWrite(10, HIGH);
    digitalWrite(11, HIGH);
    digitalWrite(12, LOW);
    hysteresis = HYSTERESIS;
  }
  else if (val1 - val2 + hysteresis < 0)
  {
    digitalWrite(9, HIGH);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
    digitalWrite(12, HIGH);
    hysteresis = -HYSTERESIS;
  }
  else {
    digitalWrite(9, LOW);
    digitalWrite(10, LOW);
    digitalWrite(11, LOW);
    digitalWrite(12, LOW);
    hysteresis = 0;
  }
}