Confused by oscilloscope - square wave signal to RPM

dovvvvv · October 3, 2021, 4:05am

*/
// Measures the HIGH width, LOW width, frequency, and duty-cycle of a pulse train
// on Arduino NANO Pin 8 (ICP1 pin).
// Note: Since this uses Timer1, Pin 9 and Pin 10 can't be used for
// analogWrite().

// Adafruit NeoPixel RGBW strips (2x8 LEDS) 

#include <MedianFilterLib.h>

//MedianFilter < volatile > medianFilter ( 5 ); // 5 samples
volatile MedianFilter<uint32_t> medianFilter(5); // 5 samples
unsigned long pulse = 0;
float sensorRPM;
int RPMno = 4000; // base rpm for led activation
int space = 100; //delays for led startup sequence

//Input for headlight circuit
#define headlights 10
bool dimmer = LOW;
unsigned long millisDimmer = 0;

//NeoPixels
#include <Adafruit_NeoPixel.h>
#define PIN 6
#define NUM_LEDS 16
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, PIN, NEO_GRBW + NEO_KHZ800);
// full brightness
uint32_t r = strip.Color  (200, 0, 0, 0);
uint32_t g = strip.Color  (0, 180, 0, 0);
uint32_t b = strip.Color  (0, 0, 255, 0);
uint32_t w = strip.Color  (0, 0, 0, 120);
uint32_t y = strip.Color  (200, 120, 0, 0);
// dimmed
uint32_t rd = strip.Color  (8, 0, 0, 0);
uint32_t gd = strip.Color  (0, 7, 0, 0);
uint32_t bd = strip.Color  (0, 0, 10, 0);
uint32_t wd = strip.Color  (0, 0, 0, 3);
uint32_t yd = strip.Color  (10, 5, 0, 0);
// off/no color
uint32_t o = strip.Color   (0, 0, 0, 0);

bool ledState = 1;

unsigned long millisLeds = 0;

void setup()
{
  //initiate neopixels
   strip.begin();
  //set strip to nothing, flushes potential random colors
  strip.clear();
  strip.fill(o);
  strip.show();
  ledStartup();
   
  //assign input for relay
  pinMode(headlights, INPUT);
  digitalWrite(headlights, HIGH); //enables pullup resistor - HIGH on an input pin
                                 //also, it inverts signal: < 3v = HIGH, > 3v = LOW
  
  Serial.begin(9600);
  while (!Serial);

  // For testing, uncomment one of these lines and connect
  // Pin 3 or Pin 5 to Pin 8
  // analogWrite(3, 64);  // 512.00, 1528.00, 2040.00, 25.10%, 490.20 Hz
  // analogWrite(5, 64);  // 260.00, 764.00, 1024.00, 25.39%, 976.56 Hz

  noInterrupts ();  // protected code
  // reset Timer 1
  TCCR1A = 0;
  TCCR1B = 0;
  TCNT1 = 0;
  TIMSK1 = 0;

  TIFR1 |= _BV(ICF1); // clear Input Capture Flag so we don't get a bogus interrupt
  TIFR1 |= _BV(TOV1); // clear Overflow Flag so we don't get a bogus interrupt

  TCCR1B = _BV(CS10) | // start Timer 1, no prescaler
           _BV(ICES1); // Input Capture Edge Select (1=Rising, 0=Falling)

  TIMSK1 |= _BV(ICIE1); // Enable Timer 1 Input Capture Interrupt
  TIMSK1 |= _BV(TOIE1); // Enable Timer 1 Overflow Interrupt
  interrupts ();

  millisLeds = millis();
  millisDimmer = millis();
}

volatile uint16_t Overflows = 0;

ISR(TIMER1_OVF_vect)
{
  Overflows++;
}

ISR(TIMER1_CAPT_vect)
{
  static uint32_t previousRisingEdgeTime = 0;

  uint32_t thisRisingEdgeTime;
  uint16_t overflows = Overflows;

  // If an overflow happened but has not been handled yet
  // and the timer count was close to zero, count the
  // overflow as part of this time.
  if ((TIFR1 & _BV(TOV1)) && (ICR1 < 1024))
    overflows++;

  // Interrupted on Rising Edge
  thisRisingEdgeTime = overflows; // Upper 16 bits
  thisRisingEdgeTime = (thisRisingEdgeTime << 16) | ICR1;

  //uint32_t pulseDuration = thisRisingEdgeTime - previousRisingEdgeTime;
  pulse = thisRisingEdgeTime - previousRisingEdgeTime;
  previousRisingEdgeTime = thisRisingEdgeTime;

  // This is a good place to add 'pulseDuration' to the median filter.
  // Make sure the median filter is marked 'volatile'.
  //medianFilter.AddValue (pulseDuration);
}

void loop()
{
  static uint32_t previousMedian;
  uint32_t thisMedian;

  if ( millis() >= millisDimmer + 250)
   {
    dimmer = digitalRead(headlights);
    millisDimmer = millis();
   }
  
  noInterrupts();
  // This would be where you get 'thisMedian'
  // from the median filter.
  thisMedian = medianFilter.AddValue (pulse);
  interrupts();

  // If a sample has been measured
  if (thisMedian != previousMedian  && thisMedian >= 0.75*previousMedian)
   {
     // Display the pulse length in microseconds
     //Serial.print("Pulse time (microseconds): ");
     //Serial.println(thisMedian / 16.0, 2);
    
     //measure revs from pulse_length
     //first calculate how many sparks happening per second, 1000ms divided by delay between sparks
     float sparksPerSec = 1000/((thisMedian / 16.0)*0.001);
     //next multiply by 60 for sparks per minute - two revs per spark
     sensorRPM = sparksPerSec*120;
     Serial.println(sensorRPM);
     //Serial.println(thisMedian);
     previousMedian = thisMedian; 
    }

  noInterrupts();
  if (millis() >= millisLeds + 50)
  {
    if (dimmer = LOW){
     leds(); }
    else {
     ledsDimmed(); }  
     millisLeds = millis();
  }
  interrupts();
}


//__      ______ _____ _____  
// \ \    / / __ \_   _|  __ \ 
//  \ \  / / |  | || | | |  | |
//   \ \/ /| |  | || | | |  | |
//    \  / | |__| || |_| |__| |
//     \/   \____/_____|_____/ 


//     _ _                               
//  __| (_)_ __ ___  _ __ ___   ___ _ __ 
// / _` | | '_ ` _ \| '_ ` _ \ / _ \ '__|
//| (_| | | | | | | | | | | | |  __/ |   
// \__,_|_|_| |_| |_|_| |_| |_|\___|_|                             

//void dimmer (void)
//{
//  
// val = digitalRead(headlights);
//  if (val == LOW) leds();
//   else            ledsDimmed();
//   
//}


//  _          _     
// | | ___  __| |___ 
// | |/ _ \/ _` / __|
// | |  __/ (_| \__ \
// |_|\___|\__,_|___/  font = ogre
                                                                 
void leds(void) 
{  
  
if (sensorRPM > 0 && sensorRPM < RPMno) 
 {
  strip.clear();
  strip.fill(o); //----------------
  strip.show(); 
 }
 
else if (sensorRPM > RPMno && sensorRPM < (RPMno + 90)) 
 {
  strip.clear();
  strip.fill(g, 14);  //gg--------------
  strip.show(); 
 }
 
else if (sensorRPM > (RPMno + 90) && sensorRPM < (RPMno + 220)) 
 {
  strip.clear();
  strip.fill(g, 12);  //gggg------------
  strip.show(); 
  } 
  
else if (sensorRPM > (RPMno + 220) && sensorRPM < (RPMno + 330)) 
 {
  strip.clear();
  strip.fill(g, 10);  //gggggg----------
  strip.show(); 
  } 
  
else if (sensorRPM > (RPMno + 330) && sensorRPM < (RPMno + 440)) 
 { 
  strip.clear();
  strip.fill(y,8);   //yyyyyyyy--------         
  strip.show(); 
  } 
  
else if (sensorRPM > (RPMno + 440) && sensorRPM < (RPMno + 550)) 
 {
  strip.clear();
  strip.fill(y,6);   //yyyyyyyyyy------
  strip.show();
 }
 
else if (sensorRPM > (RPMno + 550) && sensorRPM < (RPMno + 660)) 
 {
  strip.clear();
  strip.fill(y,4);         //yyyyyyyyyyyy----
  strip.show();  
 }
 
else if (sensorRPM > (RPMno + 660) && sensorRPM < (RPMno + 770)) 
 {
  strip.clear();strip.fill(r,2);         //rrrrrrrrrrrrrr--         
  strip.show(); 
 }
 
else if (sensorRPM > (RPMno + 770) && sensorRPM < (RPMno + 880)) 
 {
  strip.clear();
  strip.fill(r);        //rrrrrrrrrrrrrr
  strip.show(); 
 } 
 
else if (sensorRPM > (RPMno + 880) && sensorRPM < (RPMno + 1100)) 
 {
  strip.clear();
  strip.fill(w);        //wwwwwwwwwwwwwwww 
  strip.show(); 
 }


else if (sensorRPM > (RPMno + 1100)) 
 {
  strip.clear();
  strip.fill(o);
  strip.show(); 
 }
 
}

//  _          _        ___ _                              _ 
// | | ___  __| |___   /   (_)_ __ ___  _ __ ___   ___  __| |
// | |/ _ \/ _` / __| / /\ / | '_ ` _ \| '_ ` _ \ / _ \/ _` |
// | |  __/ (_| \__ \/ /_//| | | | | | | | | | | |  __/ (_| |
// |_|\___|\__,_|___/___,' |_|_| |_| |_|_| |_| |_|\___|\__,_|
                                                          
void ledsDimmed(void)  
{  
  
if (sensorRPM > 0 && sensorRPM < RPMno) 
 {
  strip.clear();
  strip.fill(o); //----------------
  strip.show(); 
 }
 
else if (sensorRPM > RPMno && sensorRPM < (RPMno + 90)) 
 {
  strip.clear();
  strip.fill(gd, 14);  //gg--------------
  strip.show(); 
 }
 
else if (sensorRPM > (RPMno + 90) && sensorRPM < (RPMno + 220)) 
 {
  strip.clear();
  strip.fill(gd, 12);  //gggg------------
  strip.show(); 
  } 
  
else if (sensorRPM > (RPMno + 220) && sensorRPM < (RPMno + 330)) 
 {
  strip.clear();
  strip.fill(gd, 10);  //gggggg----------
  strip.show(); 
  } 
  
else if (sensorRPM > (RPMno + 330) && sensorRPM < (RPMno + 440)) 
 { 
  strip.clear();
  strip.fill(yd,8);   //yyyyyyyy--------         
  strip.show(); 
  } 
  
else if (sensorRPM > (RPMno + 440) && sensorRPM < (RPMno + 550)) 
 {
  strip.clear();
  strip.fill(yd,6);   //yyyyyyyyyy------
  strip.show();
 }
 
else if (sensorRPM > (RPMno + 550) && sensorRPM < (RPMno + 660)) 
 {
  strip.clear();
  strip.fill(yd,4);         //yyyyyyyyyyyy----
  strip.show();  
 }
 
else if (sensorRPM > (RPMno + 660) && sensorRPM < (RPMno + 770)) 
 {
  strip.clear();
  strip.fill(rd,2);         //rrrrrrrrrrrrrr--         
  strip.show(); 
 }
 
else if (sensorRPM > (RPMno + 770) && sensorRPM < (RPMno + 880)) 
 {
  strip.clear();
  strip.fill(rd);        //rrrrrrrrrrrrrr
  strip.show(); 
 } 
 
else if (sensorRPM > (RPMno + 880) && sensorRPM < (RPMno + 1100)) 
 {
  strip.clear();
  strip.fill(wd);        //wwwwwwwwwwwwwwww 
  strip.show(); 
 }

else if (sensorRPM > (RPMno + 1100)) 
 {
  strip.clear();
  strip.fill(o);
  strip.show(); 
 }
}

//  _          _      __ _             _               
// | | ___  __| |___ / _\ |_ __ _ _ __| |_ _   _ _ __  
// | |/ _ \/ _` / __|\ \| __/ _` | '__| __| | | | '_ \ 
// | |  __/ (_| \__ \_\ \ || (_| | |  | |_| |_| | |_) |
// |_|\___|\__,_|___/\__/\__\__,_|_|   \__|\__,_| .__/ 
//                                             |_|    
void ledStartup(void)
{
  strip.fill(o);
  strip.show();
  delay(space);
  
  strip.fill(gd, 14);
  strip.show();
  delay(space);
  
  strip.fill(gd, 12);
  strip.show();
  delay(space);
  
  strip.fill(gd, 10); 
  strip.show();
  delay(space);
  
  strip.fill(yd,8);
  strip.show();
  delay(space);
  
  strip.fill(yd,6);
  strip.show();
  delay(space);
   
  strip.fill(yd,4);
  strip.show();
  delay(space);
  
  strip.fill(rd,2);
  strip.show();
  delay(space);
  
  strip.fill(rd);  
  strip.show();
  delay(space);
//---------------------------  
  strip.fill(wd);
  strip.show();
  delay(space*2);
//----------------------------
  strip.clear();
  strip.fill(rd);  
  strip.show();
  delay(space);

  strip.clear();
  strip.fill(rd,2);
  strip.show();
  delay(space);

  strip.clear();
  strip.fill(yd,4);
  strip.show();
  delay(space);

  strip.clear();
  strip.fill(yd,6);
  strip.show();
  delay(space);

  strip.clear();
  strip.fill(yd,8);
  strip.show();
  delay(space);
  
  strip.clear();
  strip.fill(gd, 10); 
  strip.show();
  delay(space);
  
  strip.clear();
  strip.fill(gd, 12);
  strip.show();
  delay(space);
  
  strip.clear();
  strip.fill(gd, 14);
  strip.show();
  delay(space);
  
  strip.fill(o);
  strip.show();
}

Pin 8 is not connected to anything, but pin 11/D8 is connected to the ECM ignition trigger wire IGT. See the schematic in my first post. That wire is still connected to D3, as thats where it was originally soldered to and I just added a jumper wire for testing of the timing code.
Ground is connected to both the chassis (on the left side of nano), and also the ground of the 5v dc-dc converter on the right side (on the 5v side - 12v side of the converter is connected to chassis).
See above.
A bare nano, powered by a 5v dc-dc converter, connected to the ECM, the neopixels, and also the wire coming from the stereo headlight-trigger wire, voltage divided. Again, see schematic.
Aside from a sole 250k resistor, no.

I reiterate that the RPM reading is working correctly now, and that the problem is no longer therein. Without any code for neopixels or headlights, it functions perfectly without issue.

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Confused by oscilloscope - square wave signal to RPM

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