Week 5: Electronics Production

group assignment:
      • characterize the design rules for your in-house PCB production process
      • submit a PCB design to a board house
   individual assignment:
      • make and test an embedded microcontroller system that you designed
      • extra credit: make it with another process

// Plant Monitor PCB bring-up test
// Board: Seeed XIAO ESP32C3
// IMPORTANT: Tools > "USB CDC On Boot" > Enabled
// (otherwise Serial uses UART0 on D6/D7, which are SENSOR_PWR and LED4 on your board)

const uint8_t LED_PINS[5]    = {D4, D3, D5, D7, D10};  // LED1..LED5
const uint8_t BTN1_PIN       = D0;
const uint8_t BTN2_PIN       = D8;
const uint8_t PR_PIN         = D1;
const uint8_t SOIL_PIN       = D2;
const uint8_t SENSOR_PWR_PIN = D6;

// Modes
int  ledStep   = 0;      // 0 = all off, 1..5 = single LED, 6 = all on
bool barGraph  = false;  // BTN2 toggles: LEDs show soil moisture

// Button debounce state
struct Button {
  uint8_t pin;
  bool stable = HIGH;
  bool lastRead = HIGH;
  uint32_t lastChange = 0;
};
Button b1{BTN1_PIN}, b2{BTN2_PIN};

// Returns true once on each press (falling edge)
bool pressed(Button &b) {
  bool r = digitalRead(b.pin);
  if (r != b.lastRead) { b.lastRead = r; b.lastChange = millis(); }
  if (millis() - b.lastChange > 30 && r != b.stable) {
    b.stable = r;
    if (r == LOW) return true;
  }
  return false;
}

void setLeds(int step) {
  for (int i = 0; i < 5; i++) {
    bool on = (step == 6) || (step == i + 1);
    digitalWrite(LED_PINS[i], on ? HIGH : LOW);
  }
}

void showBar(int count) {
  for (int i = 0; i < 5; i++) digitalWrite(LED_PINS[i], i < count ? HIGH : LOW);
}

void setup() {
  Serial.begin(115200);
  uint32_t t = millis();
  while (!Serial && millis() - t < 3000) {}

  pinMode(SENSOR_PWR_PIN, OUTPUT);
  digitalWrite(SENSOR_PWR_PIN, LOW);
  for (int i = 0; i < 5; i++) { pinMode(LED_PINS[i], OUTPUT); digitalWrite(LED_PINS[i], LOW); }

  // Plain INPUT on purpose: the board has external pull-ups, and this
  // will expose a missing/broken pull-up instead of hiding it.
  pinMode(BTN1_PIN, INPUT);
  pinMode(BTN2_PIN, INPUT);

  analogReadResolution(12);

  Serial.println("\n=== Plant Monitor PCB Test ===");
  Serial.println("Startup LED walk: LED1 -> LED5");
  for (int i = 1; i <= 5; i++) { setLeds(i); Serial.printf("  LED%d on\n", i); delay(400); }
  setLeds(0);
  Serial.println("BTN1: step through LEDs (off, 1-5, all on)");
  Serial.println("BTN2: toggle soil-moisture bar graph on LEDs\n");
}

void report() {
  // Power the sensors only while measuring (limits probe corrosion)
  digitalWrite(SENSOR_PWR_PIN, HIGH);
  delay(20);  // let the 100nF caps settle
  uint32_t prSum = 0, soilSum = 0;
  for (int i = 0; i < 16; i++) {
    prSum   += analogReadMilliVolts(PR_PIN);
    soilSum += analogReadMilliVolts(SOIL_PIN);
  }
  digitalWrite(SENSOR_PWR_PIN, LOW);

  uint32_t prmV = prSum / 16, soilmV = soilSum / 16;

  Serial.printf("BTN1:%-8s BTN2:%-8s | PR: %4u mV | SOIL: %4u mV\n",
                digitalRead(BTN1_PIN) ? "released" : "PRESSED",
                digitalRead(BTN2_PIN) ? "released" : "PRESSED",
                prmV, soilmV);

  if (barGraph) {
    // Uncalibrated: 0 mV -> 0 LEDs, ~2500 mV -> 5 LEDs
    showBar(constrain(map(soilmV, 0, 2500, 0, 5), 0, 5));
  }
}

void loop() {
  if (pressed(b1)) {
    barGraph = false;
    ledStep = (ledStep + 1) % 7;
    setLeds(ledStep);
    Serial.printf(">> BTN1 pressed, LED step = %d\n", ledStep);
  }
  if (pressed(b2)) {
    barGraph = !barGraph;
    if (!barGraph) setLeds(ledStep);
    Serial.printf(">> BTN2 pressed, bar graph %s\n", barGraph ? "ON" : "OFF");
  }

  static uint32_t last = 0;
  if (millis() - last >= 500) { last = millis(); report(); }
}