Getting the highest value

Using Arduino Programming Questions
1

Hi guys!

I want to get the highest value from a sensor reading.

From example, the "x" sensor returns a lot of values, when it sensor returns 200 values i need to get the highest value from this 200 values.

I hope i explained myself well. xD

1 Like
2

Show us what you have tried so far.

People are pretty helpful on here, but you will get a much better response if you show that you have at least tried.

Post any code in code tags </>.

3

What is the data type, char, byte, int, long, float?

4

We can come up with many sketches, it depends on your project what the best method is.
Nevertheless, I made this example:

int counter;          // count 200 samples
int minValue;
int maxValue;

void setup() 
{
  Serial.begin(115200);
  Serial.println( "The sketch has started");

  counter = 0;                  // start at the begin
  minValue = maxValue = SensorValue(); // give them a value from the sensor to start with
}

void loop() 
{

  int newValue = SensorValue();
  if( newValue > maxValue)
  {
    maxValue = newValue;
    Serial.print( "▲");         // this is a UTF-8 character
  }
  else if( newValue < minValue)
  {
    minValue = newValue;
    Serial.print( "▼");         // this is a UTF-8 character
  }
  else
  {
    Serial.print( "─");         // this is a UTF-8 character
  }

  counter++;
  if( counter == 200)
  {
    Serial.println();
    Serial.print( "Minimum value: ");
    Serial.print( minValue);
    Serial.print( ", ");
    Serial.print( "Maximum value: ");
    Serial.println( maxValue);

    counter = 0;                // start at the begin
    minValue = maxValue = SensorValue(); // give them a value from the sensor to start with
  }
  delay( 50);
}


int SensorValue()
{
  // This is no fun:
  //   return random( -20000, +20001);

  // This is more fun:
  return( random( -32, 32) * random( -32, 32) * random( -32, 32));
}

This sketch in Wokwi:

1 Like
5

sorry bro, was just speculating. I had nothing done, just the idea. But this is how i did it:

//ASC712 Nos da 2.5v para 0A
//La sencibilidad proporcionada por el fabricante varia dependiendo 
//de la capacidad del sensor
//float Sensibilidad = .185; //Sensicibilidad en Voltios/Amperio para sensor de 5A
float Sensibilidad = .100; //Sensicibilidad en Voltios/Amperio para sensor de 20A
//float Sensibilidad = .066; //Sensicibilidad en Voltios/Amperio para sensor de 30A

void setup() 
{
  Serial.begin(9600);
}

void loop() 
{
  float I = obtenerI(200);
  Serial.print("Corriente: ");
  Serial.println(I,3);
  //delay(100);
}

float obtenerI(int numMuestras)
{
  float voltajeSensor;
  float valorMax = 0;
  float corriente;
  for(int i = 0; i < numMuestras; i++)
  {
    voltajeSensor = analogRead(A0)*(5.0 / 1023.0); //Leemos el sensor y lo convertimos a voltaje   
    if (voltajeSensor > valorMax){
      valorMax = voltajeSensor;
    }
  }
  corriente = (valorMax - 2.5)/Sensibilidad;
  return(corriente);
}
6

Thx Koepel!

Ur code has better ideas than mine! I gonna include them to improve it!

7

The initial value is important.

This is okay, start with the lowest possible value.

float valorMax = 0;   // initial value, lowest possible value

A float number is almost never that number, since floating point numbers are approximations. For a 'float' value I prefer to set a value lower than the lowest possible value.

Assign a value that never happens, to know if something went wrong if that value has not changed. For example when reading a temperature.

float temperatureMax = -1000.0;     // initial value, this temperature will never happen

The alternative is to get a real value from the sensor as initial value. That is for sure a good value. That is what I did in my example.

1 Like
8

I hadnt thought of it that way, you are absolutely right. Thanks for everything!

9

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