Arduino Mega Read a repeating Analog Signal and Count the instances

Using Arduino Programming Questions
1

I am trying to read an analog signal. It shows a repeating pattern between 0-5 V. I just want to make the counts how many times it was 5 V.

My signal: I want to count the times it was 5 V, not the momentary spikes.

image
image1920×1080 170 KB

code:

// LED pin

int ledPin = 13;

float sig_Rain = 0; // Rain guage sensor variable

int tip_cnt = 0; // Count the tips

void setup ()

{

  Serial.begin(9600);   

  // Turn off onboard LED off

  // initialize the digital pin as an output.

  pinMode(ledPin, OUTPUT);

  digitalWrite(ledPin, LOW);   // turn the LED on (HIGH is the voltage level) 

   Serial.println("Rain_guage_signal");

}

void loop ()

{
  // Collect Raing guage sensor data

  sig_Rain = analogRead(sig_rain)*5.0/1024.0;

  // Print the raing guage 

  //Serial.print(sig_Rain,4);Serial.print(",");

  // Counter 

  if(sig_Rain<5.0){

    if(sig_Rain>4.9){

      if(sig_Rain<5.0){

        tip_cnt = tip_cnt+1;

      }

    }

  }

  Serial.print(tip_cnt);Serial.print(",");

  Serial.println();  

}

Present output:

Counter is zero. Looks like I am comparing present samples, but I have to compare previous samples. How do I do that?

2

Be very, very wary of comparing floating point values for equality.

...will never give 5V (but well-done for using the correct formula!)

3

So then, how many 5 volts in a row do you need to make it NOT a momentary spike?

4

Measure each HIGH duration (make a note of millis when you see a LOW to HIGH transition and when the reading goes to LOW calculate how long it stayed HIGH) and decide if it's a keep or not based on some threshold

5

Your suggestion seems to be made an impact. Now I edited the code and checking if it is >4.9, not =5.0. This is gives the following output:

                 Rain, Count
12:27:21.609 -> 4.9951,3559,

12:27:21.609 -> 4.9951,3560,

12:27:21.609 -> 4.9951,3561,

12:27:21.620 -> 4.9951,3562,

12:27:21.620 -> 4.9951,3563,

12:27:21.756 -> 4.9951,3564,

12:27:21.756 -> 4.9951,3565,

12:27:21.829 -> 4.8633,3565,

12:27:21.829 -> 4.0430,3565,

12:27:21.829 -> 3.3545,3565,

12:27:21.833 -> 3.2910,3565,

The problem is, it counting each instance. I want consider this whole duration as 1 count. The reason is, my sensor gives 5 V output when bucket is full, and it tips automatically by itself and next time it gives 5 V output when bucket is full again. This continues. I am counting here the number of times bucket tips.

6

Take a look at the state change detection example in the IDE, and see if you can adapt it to your needs

7

so basically it's like a momentary button that get pressed from time to time and bounces and you don't want to count the bounces

there are tons of libraries for buttons

8

1. Can you give an idea of 5V duration in ms, which will not be considered as a spike? For example: a signal between 4.5 V - 5V of > 1 ms duration would be considered as 5V and hence 1 count.

2. According to my above definition, there are 3 counts in the signal of Fig-1.
levSig
Figure-1:

3. Create a sketch to scan the signal of Fig-1 and show 3 on the Serial Monitor.

9

Thanks for referring it. I implemented it as it is with no changes. Looks like it stops at 1 because it compares only previous state. In my case, I may have to compare many samples before.

image
image1920×1080 271 KB

10

Nitpicking:

The second condition never can be true thus counter stays zero.

11

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.