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--- esp32:capacity_measure [2025/09/21 17:20] – created aistis
+++ esp32:capacity_measure [2025/09/21 17:22] (current) – aistis
@@ Line 1: / Line 1: @@
-measure capacity for
+measure capacity for wires in order to detect water level. how mutch wires are submerged in water
 {{:esp32:pasted:20250921-172035.png}}
 <code>
-sss
+#define CAP_PIN    34            // ADC input-only
+#define DRIVE_PIN  25            // per 10 MΩ (RC matavimas)
+#define FAST_PIN   27            // tiesiogiai į ● greitam pre-charge/discharge
+#define R_OHMS     10000000.0    // 10 MΩ
+const int THRESH_ADC      = 2000;    // ~1.6 V (matavimo slenkstis)
+const int ADC_LOW_FAST    = 150;     // ~artima 0 V (fast discharge)
+const int ADC_HIGH_FAST   = 3900;    // ~artima Vcc (fast charge)
+const unsigned long TIMEOUT_US     = 3000000UL;  // matavimo saugiklis
+const unsigned long TIMEOUT_FAST_US= 20000UL;    // fast fazės saugiklis (~20 ms)
+const int N_SAMPLES = 100;
+void setup() {
+  Serial.begin(115200);
+  analogSetAttenuation(ADC_11db);
+  pinMode(DRIVE_PIN, INPUT);   // Hi-Z
+  pinMode(FAST_PIN,  INPUT);   // Hi-Z
+}
+// Greitas iškrovimas iki beveik 0 V, be fiksuoto delay
+bool fast_discharge_until() {
+  pinMode(FAST_PIN, OUTPUT);
+  digitalWrite(FAST_PIN, LOW);
+  unsigned long t0 = micros();
+  int v;
+  do {
+    v = analogRead(CAP_PIN);
+    if (micros() - t0 > TIMEOUT_FAST_US) {  // saugiklis
+      pinMode(FAST_PIN, INPUT);
+      return false;
+    }
+  } while (v > ADC_LOW_FAST);
+  pinMode(FAST_PIN, INPUT); // Hi-Z, kad netrukdytų matavimui
+  return true;
+}
+// Greitas pakrovimas iki beveik Vcc, be fiksuoto delay
+bool fast_charge_until() {
+  pinMode(FAST_PIN, OUTPUT);
+  digitalWrite(FAST_PIN, HIGH);
+  unsigned long t0 = micros();
+  int v;
+  do {
+    v = analogRead(CAP_PIN);
+    if (micros() - t0 > TIMEOUT_FAST_US) {
+      pinMode(FAST_PIN, INPUT);
+      return false;
+    }
+  } while (v < ADC_HIGH_FAST);
+  pinMode(FAST_PIN, INPUT); // Hi-Z
+  return true;
+}
+unsigned long measure_rise_us() {
+  if (!fast_discharge_until()) return 0;              // 0 V startas
+  pinMode(DRIVE_PIN, OUTPUT); digitalWrite(DRIVE_PIN, HIGH); // kraunam per 10 MΩ
+  unsigned long t0 = micros();
+  while (analogRead(CAP_PIN) < THRESH_ADC) {
+    if (micros() - t0 > TIMEOUT_US) { pinMode(DRIVE_PIN, INPUT); return 0; }
+  }
+  unsigned long dt = micros() - t0;
+  pinMode(DRIVE_PIN, INPUT);   // Hi-Z
+  return dt;
+}
+unsigned long measure_fall_us() {
+  if (!fast_charge_until()) return 0;                 // Vcc startas
+  pinMode(DRIVE_PIN, OUTPUT); digitalWrite(DRIVE_PIN, LOW);  // iškraunam per 10 MΩ
+  unsigned long t0 = micros();
+  while (analogRead(CAP_PIN) > THRESH_ADC) {
+    if (micros() - t0 > TIMEOUT_US) { pinMode(DRIVE_PIN, INPUT); return 0; }
+  }
+  unsigned long dt = micros() - t0;
+  pinMode(DRIVE_PIN, INPUT);   // Hi-Z
+  return dt;
+}
+void loop() {
+  // Pastovūs koeficientai (k = Vth/Vcc)
+  const double k    = 2000.0/4095.0;
+  const double a_up = -log(1.0 - k);   // ≈ 0.673 (kilimas)
+  const double a_dn = -log(k);         // ≈ 0.717 (kritimas)
+  // Vidurkinimas per N_SAMPLES
+  double sum_tr = 0, sum_tf = 0, sum_C = 0;
+  int ok = 0;
+  for (int i = 0; i < N_SAMPLES; i++) {
+    unsigned long tr = measure_rise_us();
+    unsigned long tf = measure_fall_us();
+    if (tr == 0 || tf == 0) {
+      // praleidžiam timeout'ą
+      continue;
+    }
+    double C_up_F = (tr * 1e-6) / (R_OHMS * a_up);
+    double C_dn_F = (tf * 1e-6) / (R_OHMS * a_dn);
+    double C_pF   = (C_up_F + C_dn_F) * 0.5 * 1e12;
+    sum_tr += tr;
+    sum_tf += tf;
+    sum_C  += C_pF;
+    ok++;
+  }
+  pinMode(12, INPUT);
+  analogSetAttenuation(ADC_11db);
+  pinMode(14, OUTPUT);  digitalWrite(14, LOW);
+  delay(10);
+  double battery_voltage = analogRead(12)/4095.0 * 4.2;
+  pinMode(14, INPUT);
+  if (ok > 0) {
+    double avg_tr = sum_tr / ok;
+    double avg_tf = sum_tf / ok;
+    double avg_CpF = sum_C / ok;
+    // CSV: tr_us,tf_us,C_pF
+    Serial.printf("%.0f,%.0f,%.1f,%.1f\n", avg_tr, avg_tf, avg_CpF, battery_voltage);
+  } else {
+    Serial.println("0,0,NaN"); // jei visi matavimai suvažiavo į timeout
+  }
+ //delay(800);
+}
 </code>