when the sensor data stays the same over a range of time, turn led off. when it doesn't, turn on

i want the led off if the sensor reading stays at same value for "x" amount of time. if not, then i want it to be high. thats all. i can't get this logic down

trying to apply it to my code. not making sense. this is what i have:

Code:

//do our logic test
    if(oldDistance > newDistance)
      {
        digitalWrite(blue,HIGH);
      lastClosed = time;
      }
      else
    if((time - lastClosed) > (openTimeout ))
      {
       
        digitalWrite(blue,LOW);
      }

    }

I'm trying to disect your code, without much luck or understanding. am i on the right track with how I'm going about my sketch? something I'm missing? the time read just becomes continous and i want it to obviously change the second the new distance value changes. i know I'm missing somethingg quick but i can't get it.

Code:

int ultraSoundSignal = 8; // Ultrasound signal pin
int val = 0;
int oldDistance;
int newDistance;
int timecount; // Echo counter
int ledPin = 5;
int red = 9;
int blue = 10;
int count = 0;
unsigned long start, finished, elapsed;

void setup() {
 Serial.begin(9600);
 pinMode(ledPin, OUTPUT);
 int oldDistance = 0;
 pinMode(red,OUTPUT);
 pinMode(blue,OUTPUT);
//  oldDistance = read_the_sensor();
}
void displayResult()
{
  float h,m,s,ms;
  unsigned long over;
  elapsed=finished-start;
  h=int(elapsed/3600000);
  over=elapsed%3600000;
  m=int(over/60000);
  over=over%60000;
  s=int(over/1000);
  ms=over%1000;
  Serial.print("Raw elapsed time: ");
  Serial.println(elapsed);
  Serial.print("Elapsed time: ");
  Serial.print(h,0);
  Serial.print("h ");
  Serial.print(m,0);
  Serial.print("m ");
  Serial.print(s,0);
  Serial.print("s ");
  Serial.print(ms,0);
  Serial.println("ms");
  Serial.println(); 
}

    void loop() {
      if(timecount > 0){
      digitalWrite(ledPin, HIGH);
    }

      oldDistance = read_the_sensor();
   
              delay(300);
      newDistance = read_the_sensor();
 

    //newDistance = timecount; //  echo pulse time to newDistance
    Serial.print("New Distance  = "); // Example identifier for the sensor
    Serial.print(newDistance);
    Serial.write(10);
    Serial.write(13);

    //oldDistance = timecount; //  echo pulse time to newDistance
    Serial.print("Old Distance  = "); // Example identifier for the sensor
    Serial.print(oldDistance);
    Serial.write(10);
    Serial.write(13);
   

    /* Lite up LED if any value is passed by the echo pulse
     * -------------------------------------------------------------------
     */
if (newDistance =! oldDistance){
    start=millis();
    delay(200); // for debounce   
    Serial.println("Started...");

    //digitalWrite(led, HIGH);
   
}else{
 
   
    finished=millis();
    delay(200); // for debounce
    displayResult();
   
}}
 
 
 
  //    //do our logic test
//    if(oldDistance > newDistance)
//      {
//        digitalWrite(red,HIGH);
//        digitalWrite(blue,LOW);
//      }
//      else
//    if(oldDistance < newDistance)
//      {
//        digitalWrite(red,LOW);
//        digitalWrite(blue,HIGH);
//      }
//
//    }



int read_the_sensor() {
timecount = 0;
val = 0;
pinMode(ultraSoundSignal, OUTPUT); // Switch signalpin to output

/* Send low-high-low pulse to activate the trigger pulse of the sensor
* -------------------------------------------------------------------
*/

digitalWrite(ultraSoundSignal, LOW); // Send low pulse
delayMicroseconds(2); // Wait for 2 microseconds
digitalWrite(ultraSoundSignal, HIGH); // Send high pulse
delayMicroseconds(5); // Wait for 5 microseconds
digitalWrite(ultraSoundSignal, LOW); // Holdoff

/* Listening for echo pulse
* -------------------------------------------------------------------
*/

pinMode(ultraSoundSignal, INPUT); // Switch signalpin to input
val = digitalRead(ultraSoundSignal); //  signal value to val
while(val == LOW) { // Loop until pin reads a high value
 val = digitalRead(ultraSoundSignal);
  }

while(val == HIGH) { // Loop until pin reads a high value
 val = digitalRead(ultraSoundSignal);
 timecount = timecount +1;            // Count echo pulse time
  }

return timecount;
}

If it is the same, you need to compare the time since the change (Hint: Millis() - timeSinceChange) to see if it's greater than a certain interval.

i want to summarize that when this sensor value has not changed over a specific period of time, do something. I'm not understanding how what i quoted will do that. i may be wrong. i can't visually understand it.

PaulS, im unclear then how to implement millis.

code thus far:

Code:

int lastVal = 0;
unsigned long change = 0;
int signalPin = 8;     
long elapsedtime = 0;

int led = 5;
void setup()
{

  Serial.begin(9600);
}




void loop()
{

  elapsedtime = 0;
  pinMode(signalPin, OUTPUT);

  // Send 0-1-0 pulse to activate the sensor
  digitalWrite(signalPin, LOW);
  delayMicroseconds(2);
  digitalWrite(signalPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(signalPin, LOW);

  // Listen to pulse
  pinMode(signalPin, INPUT);               
  elapsedtime = pulseIn(signalPin, HIGH);

  // print value through Serial

  Serial.println(elapsedtime, DEC);


  int valueCurrent = digitalRead(signalPin);
  if (valueCurrent =! lastVal) {  //should lastval be millis?

    digitalWrite(led, HIGH); //do something

  }
  else {

    digitalWrite(led, LOW);

  }
}

how would i reset millis() ?  how to apply it to sensor pin? I've read documentation and understand it, but i can't grasp how to apply it. to reset... and then it seems like i need some more logic?

so i did a little quick mach up but i know I'm missing some key parts. I'm just confused on specific syntax to use. heres what i got:

Code:

boolean lastVal = 0;              //last reading
int change = 0;   

int sensorPin = 8;

if(sensorPin =! lastVal ){

//blink led or whatever action

}
else {

change //confused here on how to set the "change to now". use millis?

}

I'm trying to compare if a sensor datas range stays the same over "x" amount of time, to do something. I'm kinda struggling on the syntax, so any help would be great. heres a basic ping sensor code I'm using:

Code:

int signalPin = 8;     // sensor signal pin connected to wiring pin 0
long elapsedtime = 0;

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

void loop()
{
  elapsedtime = 0;
  pinMode(signalPin, OUTPUT);  // set signalPin as OUTPUT

  // Send 0-1-0 pulse to activate the sensor
  digitalWrite(signalPin, LOW);
  delayMicroseconds(2);
  digitalWrite(signalPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(signalPin, LOW);

  // Listen to pulse
  pinMode(signalPin, INPUT);               // set signalPin as INPUT
  elapsedtime = pulseIn(signalPin, HIGH);  // get the length of the pusle while it is HIGH

  // print value through Serial

  Serial.println(elapsedtime, DEC);
  delay(100);
}

http://arduino.cc/en/Reference/Bitshift

basically its shifting within binary. i think. i mentioned the line of code from my sketch, which was this:

 phaccu=phaccu+tword_m; // soft DDS, phase accu with 32 bits
 
  icnt=phaccu >> 24; //  this number, 24, i want to be able to become adjustable with mapped values from a pot with a min or 1 and max of 28.

hope this clarified a bit.

i do not understand at all how to apply that.

truthfully i dont understand everything going on inside it. i know what number causes the result i want, and i want a way to map it according to pot values. refer above for specifics

so i found this sine wave sketch and i want to make it adjustable. reading through documentation, I'm trying to take a number that is a bit shift in the sketch and map it to a pot. everything I've tried has disabled the first mapped pot in the sketch. heres the code:


as you read below, the number i want to map from 1-28 with a pot is this portion:

phaccu=phaccu+tword_m;
  icnt=phaccu >> 24;     <<this number. refer to rest of code below.

Code:

#include "avr/pgmspace.h"

// table of 256 sine values / one sine period / stored in flash memory
PROGMEM  prog_uchar sine256[]  = {
  127,130,133,136,139,143,146,149,152,155,158,161,164,167,170,173,176,178,181,184,187,190,192,195,198,200,203,205,208,210,212,215,217,219,221,223,225,227,229,231,233,234,236,238,239,240,
  242,243,244,245,247,248,249,249,250,251,252,252,253,253,253,254,254,254,254,254,254,254,253,253,253,252,252,251,250,249,249,248,247,245,244,243,242,240,239,238,236,234,233,231,229,227,225,223,
  221,219,217,215,212,210,208,205,203,200,198,195,192,190,187,184,181,178,176,173,170,167,164,161,158,155,152,149,146,143,139,136,133,130,127,124,121,118,115,111,108,105,102,99,96,93,90,87,84,81,78,
  76,73,70,67,64,62,59,56,54,51,49,46,44,42,39,37,35,33,31,29,27,25,23,21,20,18,16,15,14,12,11,10,9,7,6,5,5,4,3,2,2,1,1,1,0,0,0,0,0,0,0,1,1,1,2,2,3,4,5,5,6,7,9,10,11,12,14,15,16,18,20,21,23,25,27,29,31,
  33,35,37,39,42,44,46,49,51,54,56,59,62,64,67,70,73,76,78,81,84,87,90,93,96,99,102,105,108,111,115,118,121,124

};
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))

int ledPin = 13;                 // LED pin 7
int testPin = 7;
int t2Pin = 6;
byte bb;
 
double dfreq;
// const double refclk=31372.549;  // =16MHz / 510
const double refclk=31376.6;      // measured

// variables used inside interrupt service declared as voilatile
volatile byte icnt;              // var inside interrupt
volatile byte icnt1;             // var inside interrupt
volatile byte c4ms;              // counter incremented all 4ms
volatile unsigned long phaccu;   // pahse accumulator
volatile unsigned long tword_m;  // dds tuning word m

void setup()
{
  pinMode(ledPin, OUTPUT);      // sets the digital pin as output
  Serial.begin(115200);        // connect to the serial port
  Serial.println("DDS Test");

  pinMode(6, OUTPUT);      // sets the digital pin as output
  pinMode(7, OUTPUT);      // sets the digital pin as output
  pinMode(11, OUTPUT);     // pin11= PWM  output / frequency output

  Setup_timer2();

  // disable interrupts to avoid timing distortion
  cbi (TIMSK0,TOIE0);              // disable Timer0 !!! delay() is now not available
  sbi (TIMSK2,TOIE2);              // enable Timer2 Interrupt

  dfreq=1000.0;                    // initial output frequency = 1000.o Hz
  tword_m=pow(2,32)*dfreq/refclk;  // calulate DDS new tuning word

}
void loop()
{
//  while(1) {
//     if (c4ms > 250) {                 // timer / wait fou a full second
//      c4ms=0;
     
     
     
      dfreq=analogRead(0);     
 tword_m = dfreq;
tword_m = map(tword_m, 0, 140032752, 0, 1023 );      // read Poti on analog pin 0 to adjust output frequency from 0..1023 Hz

      cbi (TIMSK2,TOIE2);              // disble Timer2 Interrupt
      tword_m=pow(2,32)*dfreq/refclk;  // calulate DDS new tuning word
      sbi (TIMSK2,TOIE2);              // enable Timer2 Interrupt

      Serial.print(dfreq);
      Serial.print("  ");
      Serial.println(tword_m);
   

   sbi(PORTD,6); // Test / set PORTD,7 high to observe timing with a scope
   cbi(PORTD,6); // Test /reset PORTD,7 high to observe timing with a scope
  }
 
//******************************************************************
// timer2 setup
// set prscaler to 1, PWM mode to phase correct PWM,  16000000/510 = 31372.55 Hz clock
void Setup_timer2() {

// Timer2 Clock Prescaler to : 1
  sbi (TCCR2B, CS20);
  cbi (TCCR2B, CS21);
  cbi (TCCR2B, CS22);

  // Timer2 PWM Mode set to Phase Correct PWM
  cbi (TCCR2A, COM2A0);  // clear Compare Match
  sbi (TCCR2A, COM2A1);

  sbi (TCCR2A, WGM20);  // Mode 1  / Phase Correct PWM
  cbi (TCCR2A, WGM21);
  cbi (TCCR2B, WGM22);
}

//******************************************************************
// Timer2 Interrupt Service at 31372,550 KHz = 32uSec
// this is the timebase REFCLOCK for the DDS generator
// FOUT = (M (REFCLK)) / (2 exp 32)
// runtime : 8 microseconds ( inclusive push and pop)
ISR(TIMER2_OVF_vect) {

  sbi(PORTD,7);          // Test / set PORTD,7 high to observe timing with a oscope

  phaccu=phaccu+tword_m; // soft DDS, phase accu with 32 bits
  icnt=phaccu >> 24;     // use upper 8 bits for phase accu as frequency information (this is also what i want to map from 1-28)
                         // read value fron ROM sine table and send to PWM DAC
  OCR2A=pgm_read_byte_near(sine256 + icnt);   

  if(icnt1++ == 125) {  // increment variable c4ms all 4 milliseconds
    c4ms++;
    icnt1=0;
   }   

 cbi(PORTD,7);            // reset PORTD,7
}

great. do you have an example of this aside from the arduino example? I'm not understanding how they use it really.