Logging analogue data using a rc to Start and Stop

[doylie99]

Hi,

I'm trying to make a cataloguer to log current and motor temp on a rc car. Ideally using a channel on the rc to start and stop logging.

So far, I have interrupt code to measure the PWM width and start and stop logging depending on a threshold value. This Works OK.

The problem Im getting is that I'm getting a error in the analogue read, easier to show an example than explain. Below is data from the serial link.

12:10:19.782 -> START
12:10:19.782 -> 707
12:10:19.819 -> 709
12:10:19.819 -> 30
12:10:19.852 -> 30
12:10:19.852 -> 30
12:10:19.889 -> 31
12:10:19.889 -> 30
12:10:19.924 -> 30
12:10:19.957 -> 31
12:10:19.957 -> 31
12:10:19.992 -> 30
12:10:19.992 -> 30
12:10:20.027 -> 30
12:10:20.027 -> 30
12:10:20.060 -> 30
12:10:20.094 -> 707
12:10:20.094 -> 707
12:10:20.131 -> 707
12:10:20.131 -> 30
12:10:20.166 -> 30
12:10:20.204 -> 30
12:10:20.204 -> 30
12:10:20.241 -> 30
12:10:20.241 -> 30
12:10:20.275 -> 30

This is at development stage, so all I have for an input is a pot, looking at the above data I'm getting spurious 707 values at regular intervals. I'm guessing this is being caused by a misread of the analogue during interrupt.

Any idea how to prevent this?

//assume that pin 32 is receiving PWM input
#define CHANNEL_1_PIN 2

int pulse_time  = 0;
int dump = 0;
bool startLogging = LOW;
bool endSent = HIGH;
bool startSent = LOW;
const int analogInPin = A0;
bool pause = LOW;
//micros when the pin goes HIGH
volatile unsigned long timer_start;

//difference between timer_start and micros() is the length of time that the pin 
//was HIGH - the PWM pulse length. volatile int pulse_time; 
//this is the time that the last interrupt occurred. 
//you can use this to determine if your receiver has a signal or not. 

volatile int last_interrupt_time; //calcSignal is the interrupt handler 

void calcSignal() 
{
    //record the interrupt time so that we can tell if the receiver has a signal from the transmitter 
    last_interrupt_time = micros(); 
    pause = HIGH;
    //analogRead(analogInPin);
    //if the pin has gone HIGH, record the microseconds since the Arduino started up 
    if(digitalRead(CHANNEL_1_PIN) == HIGH) 
    { 
        timer_start = micros();
    } 
    //otherwise, the pin has gone LOW 
    else
    { 
        //only worry about this if the timer has actually started
        if(timer_start != 0)
        { 
            //record the pulse time
            pulse_time = (micros() - timer_start);
            //restart the timer
            timer_start = 0;
        }
    } 
  dump = analogRead(analogInPin); 
} 
 
//this is all normal arduino stuff 
void setup() 
{
    timer_start = 0; 
    pinMode(12, OUTPUT);
    attachInterrupt(CHANNEL_1_PIN, calcSignal, CHANGE);
    Serial.begin(9600);
    pause = LOW;
} 
 
void loop()
{
    //Serial.println(pulse_time);
    
    if (pulse_time > 1750){
      Serial.println("START");
      endSent = LOW;
      digitalWrite(12, HIGH);
      while(pulse_time > 1750 ){
        if(!pause){
          
          Serial.println(dump) ;
          
        }
        delay(205);
        pause = LOW;
        
      }
    }
      if (!endSent ){
        Serial.println("END");
      endSent = HIGH;
      digitalWrite(12, LOW);
      }
  
}

[Idahowalker]

Hey, I'm old and have not had my coffee yet this AM. Could you do me a favor and edit your post and use those so called code tag thingies </> around your code? Code tags make things like reading your code much easier.

See:

attachInterrupt(CHANNEL_1_PIN, calcSignal, CHANGE);
Serial.begin(9600);
pause = LOW;
}

void loop()
{
//Serial.println(pulse_time);

if (pulse_time > 1750){
  Serial.println("START");
  endSent = LOW;
  digitalWrite(12, HIGH);
  while(pulse_time > 1750 ){
    if(!pause){
      Serial.println(analogRead(analogInPin));
    }
    

[doylie99]

Will do, first time post and learning the ropes. Bear with me.