// https://wokwi.com/projects/463632973167872001
// https://forum.arduino.cc/t/writing-code-for-an-analogue-tachometer-powered-by-attiny85/1443125

# include <TinyDebug.h>

// hack for wokwi development lose all this and all serial printing for ATTiny
# define Serial Debug

// Demonstration sketch only.
// truncated and running on the ATTiny w/ wokwi Debug

// Shows the structure: input -> [lookup/interpolation -> correction ->] output.

const byte frequencyOutputPin = 7;  // ?? not yet. what ATTiny pin?
const byte voltageSensePin    = A3;
const byte coilInputPin       = PB2;

//... status LEDs, lose 'em if
const byte good = PB1;  // pulses be being seen
const byte bad = PB4;   // nothing valid to -> PWM

void setup() {

  Debug.begin();
  Debug.println(F("Hello, TinyDebug!"));
  pinMode(good, OUTPUT);
  pinMode(bad, OUTPUT);

// pinMode(frequencyOutputPin, OUTPUT);
 pinMode(voltageSensePin, INPUT);
 pinMode(coilInputPin, INPUT);
}

void loop() {
  static unsigned long cpounter;
  Serial.print(cpounter); Serial.print(" ");
  cpounter++;

 // ----- INPUT -----
  digitalWrite(good, LOW);
  digitalWrite(bad, LOW);

  int analogReading = analogRead(voltageSensePin);
  
  unsigned long upT, downT;
  upT = pulseIn(coilInputPin, HIGH,  200000);  // wait 0.2 seconds each
  downT = pulseIn(coilInputPin, LOW, 200000);

  if (!upT || !downT) {
    Serial.println("no pulse");
    digitalWrite(bad, HIGH);

    delay(100);  // spam - goes away with a timed loop execution rate
    return;  // no valid pulse, nothing else to do
  }
  // else
  digitalWrite(good, HIGH);

  unsigned long pulseTime = upT + downT;

// PROCESS - nothing here yet


// OUTPUT

// frequency
if (0) {  // 1 will show pulse frequency, who cares? It works
  Serial.print("Hz: ");
  Serial.print(1000000.0 / pulseTime, 1);
}
  
// RPM
  Serial.print(" RPM: ");
  Serial.print(60000000.0 / pulseTime, 1);

if (0) {  // 1 will show analog reading, who cares? It works
  Serial.print("    voltageSensePin: ");
  Serial.print(analogReading);
}

  Serial.println("");

  delay(100);  // throttle/spam: do this right millis()-style - execute loop every X milliseconds
}