problem in SoilMoistSensor

[Reza]

@mfalkvidd
this is not true !
in my app (imperihome) is -1% now !!! and after sense is -8 or -28 or +20 and . . .

[BulldogLowell]

@Reza

why not post the sketch you are using?

[Reza]

@BulldogLowell hi
I use same code in mysesors.org without any changes

#include <math.h> // Conversion equation from resistance to %
#include <SPI.h>
#include <MySensor.h>

// Setting up format for reading 3 soil sensors
#define NUM_READS 10 // Number of sensor reads for filtering
#define CHILD_ID 0

MySensor gw; // Arduino initialization
MyMessage msg(CHILD_ID, V_LEVEL);
unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in milliseconds)

long buffer[NUM_READS];
int index;

typedef struct { // Structure to be used in percentage and resistance values matrix to be filtered (have to be in pairs)
int moisture;
long resistance;
} values;

const long knownResistor = 4700; // Constant value of known resistor in Ohms

int supplyVoltage; // Measured supply voltage
int sensorVoltage; // Measured sensor voltage

values valueOf[NUM_READS]; // Calculated moisture percentages and resistances to be sorted and filtered

int i; // Simple index variable

void setup() {
// initialize serial communications at 9600 bps:
Serial.begin(115200);
gw.begin();
gw.sendSketchInfo("Soil Moisture Sensor Reverse Polarity", "1.0");
gw.present(CHILD_ID, S_HUM);
// initialize the digital pins as an output.
// Pin 6,7 is for sensor 1
// initialize the digital pin as an output.
// Pin 6 is sense resistor voltage supply 1
pinMode(6, OUTPUT);

// initialize the digital pin as an output.
// Pin 7 is sense resistor voltage supply 2
pinMode(7, OUTPUT);

}

void loop() {

measure(6,7,1);
Serial.print ("\t");
Serial.println (average());
long read1 = average();

measure(7,6,0);
Serial.print ("\t");
Serial.println (average());
long read2= average();

long sensor1 = (read1 + read2)/2;

Serial.print ("resistance bias =" );
Serial.println (read1-read2);
Serial.print ("sensor bias compensated value = ");
Serial.println (sensor1);
Serial.println ();

//send back the values
gw.send(msg.set((long int)ceil(sensor1)));
// delay until next measurement (msec)
gw.sleep(SLEEP_TIME);

}

void measure (int phase_b, int phase_a, int analog_input)
{
// read sensor, filter, and calculate resistance value
// Noise filter: median filter

for (i=0; i<NUM_READS; i++) {

// Read 1 pair of voltage values
digitalWrite(phase_a, HIGH);                 // set the voltage supply on
delayMicroseconds(25);
supplyVoltage = analogRead(analog_input);   // read the supply voltage
delayMicroseconds(25);
digitalWrite(phase_a, LOW);                  // set the voltage supply off
delay(1);

digitalWrite(phase_b, HIGH);                 // set the voltage supply on
delayMicroseconds(25);
sensorVoltage = analogRead(analog_input);   // read the sensor voltage
delayMicroseconds(25);
digitalWrite(phase_b, LOW);                  // set the voltage supply off

// Calculate resistance
// the 0.5 add-term is used to round to the nearest integer
// Tip: no need to transform 0-1023 voltage value to 0-5 range, due to following fraction
long resistance = (knownResistor * (supplyVoltage - sensorVoltage ) / sensorVoltage) ;

delay(1);
addReading(resistance);
Serial.print (resistance);
Serial.print ("\t");

}
}

// Averaging algorithm
void addReading(long resistance){
buffer[index] = resistance;
index++;
if (index >= NUM_READS) index = 0;
}

long average(){
long sum = 0;
for (int i = 0; i < NUM_READS; i++){
sum += buffer[i];
}
return (long)(sum / NUM_READS);
}

[BulldogLowell]

@Reza

Well, I really don't like a few things in that sketch, like the struct that is never used, for example.

or using a global variable as an array index:

int i; // Simple index variable

or superfluous nonsense comments:

// initialize serial communications at 9600 bps:
  Serial.begin(115200);

The other thing is that the "average" function may be using junk until you take 10 readings, and that takes 5 minutes to clear out:

long buffer[NUM_READS];

try this instead which will initialize the array to zeroes:

long buffer[NUM_READS] = {0};

also, we ought to modify the addReading() and average() functions to size itself for the first 9 readings....

There may be other datatype issues, but let's start here.

[Reza]

@BulldogLowell said:

or superfluous nonsense comments:

my friend i am weak in coding, I just use this device for my home . so please Correction the code and send to me . please
thank you <3

[BulldogLowell]

@Reza

well, I have no way of testing :(

but I would do like this:

#include <math.h> // Conversion equation from resistance to %
#include <SPI.h>
#include <MySensor.h>
#include "CircularBuffer.h"

#define NUM_READS 10 // Number of sensor reads for filtering
#define CHILD_ID 0

CircularBuffer forward(NUM_READS);
CircularBuffer reverse(NUM_READS);

MySensor gw; // Arduino initialization
MyMessage msg(CHILD_ID, V_LEVEL);

unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in milliseconds)

long buffer[NUM_READS];

const long knownResistor = 4700; // Constant value of known resistor in Ohms

void setup() 
{
  Serial.begin(9600);
  gw.begin();
  gw.sendSketchInfo("Soil Moisture Sensor Reverse Polarity", "1.0");
  gw.present(CHILD_ID, S_HUM);
  pinMode(6, OUTPUT);
  pinMode(7, OUTPUT);
}

void loop() 
{
  forward.addElement(measure(6, 7, 1));
  reverse.addElement(measure(7, 6, 0));
  Serial.print ("forward average:");
  Serial.println (forward.mean());
  Serial.print ("reverse average:");
  Serial.println (reverse.mean());

  float sensor1 = long((forward.mean() + reverse.mean()) / 2.0);

  Serial.print ("resistance bias =" );
  Serial.println (forward.mean() - reverse.mean());
  Serial.print ("sensor bias compensated value = ");
  Serial.println (sensor1);
  Serial.println ();

  gw.send(msg.set((long int)ceil(sensor1)));
  gw.sleep(SLEEP_TIME);
}

long int measure (int phase_b, int phase_a, int analog_input)
{
  for (int i = 0; i < NUM_READS; i++) 
  {
    // Read 1 pair of voltage values
    digitalWrite(phase_a, HIGH);                 // set the voltage supply on
    delayMicroseconds(25);
    long int supplyVoltage = analogRead(analog_input);   // read the supply voltage
    delayMicroseconds(25);
    digitalWrite(phase_a, LOW);                  // set the voltage supply off
    delay(1);

    digitalWrite(phase_b, HIGH);                 // set the voltage supply on
    delayMicroseconds(25);
    long int sensorVoltage = analogRead(analog_input);   // read the sensor voltage
    delayMicroseconds(25);
    digitalWrite(phase_b, LOW);                  // set the voltage supply off
    delay(1);
    return long((knownResistor * (supplyVoltage - sensorVoltage ) / sensorVoltage));
  }
}

1: Start wiht a new sketch
2: add two tabs to the sketch like this:

3: paste these library files into the two tabs:
CircularBuffer.h

#ifndef CircularBuffer_h
#define CircularBuffer_h

#include <Arduino.h>

class CircularBuffer {
  public:
    CircularBuffer(size_t size);
    void addElement(float newElement);
    float mean();
    float maxVal();
    float minVal();
    float sigma();
    size_t numElements();
    float arrayElement(int location);

  private:
    float* array;
    float* next;
    size_t size;
    int index = 0;
    int num_elements = 0;
};

#endif

CircularBuffer.cpp

#include "CircularBuffer.h"
#include <Arduino.h>

CircularBuffer::CircularBuffer(size_t arraySize)
{
  size = arraySize;
  array = new float[arraySize];
  next = &array[0];
}

void CircularBuffer::addElement(float newElement)
{
  *next = newElement;
  index++;
  if (index >= size)
  {
    index = 0;
  }
  next = &array[index];
  if (++num_elements > size)
  {
    num_elements = size;
  }
}

float CircularBuffer::arrayElement(int location)
{
  return array[location];
}


float CircularBuffer::mean()
{
  float average = 0;
  for (int i = 0; i < num_elements; i++)
  {
    average += array[i];
  }
  return average / num_elements;
}

size_t CircularBuffer::numElements()
{
  return num_elements;
}

float CircularBuffer::maxVal()
{
  float maximum;
  for (int i = 0; i < num_elements; i++)
  {
    if (i == 0)
    {
      maximum = array[0];
    }
    else if (array[i] > maximum)
    {
      maximum =  array[i];
    }
  }
  return maximum;
}
float CircularBuffer::minVal()
{
  float minimum;
  for (int i = 0; i < num_elements; i++)
  {
    if (i == 0)
    {
      minimum = array[0];
    }
    else if (array[i] < minimum)
    {
      minimum =  array[i];
    }
  }
  return minimum;
}
float CircularBuffer::sigma()
{
  float average = mean();
  float sigma = 0;
  for(int i = 0; i < min(size, num_elements) ; i++)
  {
    sigma += ((array[i] - average) * (array[i] - average));
  }
  return sqrt(sigma / min(size, num_elements));
}

[Reza]

@BulldogLowell said:

#include "CircularBuffer.h"
#include <Arduino.h>

CircularBuffer::CircularBuffer(size_t arraySize)
{
size = arraySize;
array = new float[arraySize];
next = &array[0];
}

void CircularBuffer::addElement(float newElement)
{
*next = newElement;
index++;
if (index >= size)
{
index = 0;
}
next = &array[index];
if (++num_elements > size)
{
num_elements = size;
}
}

float CircularBuffer::arrayElement(int location)
{
return array[location];
}

float CircularBuffer::mean()
{
float average = 0;
for (int i = 0; i < num_elements; i++)
{
average += array[i];
}
return average / num_elements;
}

size_t CircularBuffer::numElements()
{
return num_elements;
}

float CircularBuffer::maxVal()
{
float maximum;
for (int i = 0; i < num_elements; i++)
{
if (i == 0)
{
maximum = array[0];
}
else if (array[i] > maximum)
{
maximum = array[i];
}
}
return maximum;
}
float CircularBuffer::minVal()
{
float minimum;
for (int i = 0; i < num_elements; i++)
{
if (i == 0)
{
minimum = array[0];
}
else if (array[i] < minimum)
{
minimum = array[i];
}
}
return minimum;
}
float CircularBuffer::sigma()
{
float average = mean();
float sigma = 0;
for(int i = 0; i < min(size, num_elements) ; i++)
{
sigma += ((array[i] - average) * (array[i] - average));
}
return sqrt(sigma / min(size, num_elements));
}

this is not true .i test with full water and few water and no water but Numbers in disarray for example first secend is -8% and next 2% and next -16% and next 24% and next -7% . . .

[BulldogLowell]

@Reza said:

this is not true .i test with full water and few water and no water but Numbers in disarray for example first secend is -8% and next 2% and next -16% and next 24% and next -7% . . .

I don't know what "this is not true" is meant to say...

As I mentioned, I cannot test. Perhaps you could show the Serial output using this modification of the sketch, changing the sleep in loop() to this:

delay(1000);

[Reza]

@BulldogLowell
amount of humidity should be between 0 and 100% . is it true ? but my sensor showed me the different numbers.for example -8% -30% and....

[BulldogLowell]

@Reza

you should show the output of the Serial Monitor.

There may be a variable overflowing...