3. Smart Tank and Pump Control

#include <PxServ.h>
 
const char* WIFI_SSID = "your_wifi_ssid";
const char* WIFI_PASSWORD = "your_wifi_password";
const char* PXSERV_API_KEY = "your_pxserv_api_key";
const int TRIG_PIN = 5, ECHO_PIN = 18, HIGH_FLOAT_PIN = 19, PUMP_PIN = 23;
const float EMPTY_CM = 90.0, FULL_CM = 10.0;
const float START_LEVEL = 30.0, STOP_LEVEL = 80.0;
const unsigned long MAX_RUN_MS = 60000;
 
PxServ client(PXSERV_API_KEY);
bool pumpOn = false, timeoutFault = false;
unsigned long pumpStartedAt = 0, lastCycleAt = 0;
 
float readDistanceCm() {
  digitalWrite(TRIG_PIN, LOW); delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH); delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  unsigned long duration = pulseIn(ECHO_PIN, HIGH, 30000);
  return duration == 0 ? -1 : duration * 0.0343f / 2.0f;
}
 
void setPump(bool enabled) {
  if (pumpOn == enabled) return;
  pumpOn = enabled;
  digitalWrite(PUMP_PIN, enabled ? LOW : HIGH);
  if (enabled) pumpStartedAt = millis();
}
 
void publishState(float level, String state) {
  client.setData("tank-pump/level", String(level, 1));
  client.setData("tank-pump/pump", pumpOn ? "1" : "0");
  client.setData("tank-pump/status", state);
}
 
void setup() {
  Serial.begin(115200);
  pinMode(TRIG_PIN, OUTPUT); pinMode(ECHO_PIN, INPUT);
  pinMode(HIGH_FLOAT_PIN, INPUT_PULLUP); pinMode(PUMP_PIN, OUTPUT);
  digitalWrite(PUMP_PIN, HIGH);
  PxServ::connectWifi(WIFI_SSID, WIFI_PASSWORD);
}
 
void loop() {
  unsigned long now = millis();
  if (pumpOn && now - pumpStartedAt >= MAX_RUN_MS) {
    setPump(false); timeoutFault = true;
  }
  if (now - lastCycleAt < 3000) { delay(20); return; }
  lastCycleAt = now;
 
  bool highFloatActive = digitalRead(HIGH_FLOAT_PIN) == LOW;
  float distance = readDistanceCm();
  if (highFloatActive) { setPump(false); publishState(100, "high-limit"); return; }
  if (distance < 0) { setPump(false); publishState(-1, "sensor-error"); return; }
 
  float level = constrain(
    (EMPTY_CM - distance) * 100.0f / (EMPTY_CM - FULL_CM), 0.0f, 100.0f
  );
  PxServ::Callback reset = client.getData("tank-pump/reset-fault");
  if (reset.status == 200 && reset.data == "1") {
    timeoutFault = false;
    client.setData("tank-pump/reset-fault", "0");
  }
  if (timeoutFault) { setPump(false); publishState(level, "timeout-fault"); return; }
 
  String mode = "automatic";
  PxServ::Callback modeValue = client.getData("tank-pump/mode");
  if (modeValue.status == 200) mode = modeValue.data;
  bool request = false;
  if (mode == "manual") {
    PxServ::Callback manual = client.getData("tank-pump/manual-command");
    request = manual.status == 200 && manual.data == "1";
  } else {
    request = pumpOn ? level < STOP_LEVEL : level < START_LEVEL;
  }
  setPump(request);
  publishState(level, pumpOn ? "filling" : "waiting");
}