// Microvolt serial streamer: prints one line per sample, comma-separated, for the Web Serial plotter.
// Works on an Arduino Uno/Nano (10-bit ADC) or an ESP32 (12-bit). Adjust the pins and rate below.
//
// Wiring for Phase 1 project B ("One channel of you"): amplifier output -> A0, amplifier mid-supply reference -> A1.
// The plotter subtracts nothing for you; print what you want to see.

const int PIN_SIGNAL = A0;
const int PIN_REF    = A1;         // optional second channel; comment out below if unused
const unsigned long SAMPLE_US = 4000; // 4000 us = 250 samples per second

unsigned long nextSample = 0;

void setup() {
  Serial.begin(115200);
  analogReference(DEFAULT);       // Uno/Nano: 5 V full scale. For 1.1 V full scale use INTERNAL.
  nextSample = micros();
}

void loop() {
  unsigned long now = micros();
  if ((long)(now - nextSample) >= 0) {
    nextSample += SAMPLE_US;      // fixed-interval scheduling, immune to how long Serial.print takes
    int sig = analogRead(PIN_SIGNAL);
    int ref = analogRead(PIN_REF);
    Serial.print(sig);
    Serial.print(',');
    Serial.println(ref);
  }
}