// https://wokwi.com/projects/428322248636228609
// for https://forum.arduino.cc/t/problems-with-photodiode-ir-receiver/1372146/142?u=davex

void setup() {
  pinMode(2, INPUT_PULLUP);
  Serial.begin(115200);
  Serial.println(F(R"(pulseIn demo - 
note that this skips every other pulse
because pulsein(pin,HIGH) matches a full ___/---\___ cycle
and pulsein(pin,LOW) matches a full ---\___/--- cycle
See https://docs.arduino.cc/language-reference/en/functions/advanced-io/pulseIn/ )"));
}

void loop() {
  long duration;
  duration = pulseIn(2, LOW, 10000000);
  Serial.print("LOW:");
  Serial.print(duration);
  duration = pulseIn(2, HIGH, 10000000);
  Serial.print(" HIGH:");
  Serial.println(duration);
}