Saving settings

The library can save values in the ESP32's flash memory. They survive restarts and power cuts, which is useful for settings such as a threshold, a mode or the last state of an output.

// Save
iot.saveString("device_name", "Sensor-01");
iot.saveInt   ("threshold",   30);
iot.saveFloat ("last_lat",    23.0225);
iot.saveBool  ("alarm_on",    false);

// Load: the second argument is returned if the key was never saved
String name  = iot.getString("device_name", "Unknown");
int    thr   = iot.getInt   ("threshold",   25);
float  lat   = iot.getFloat ("last_lat",    0.0);
bool   alarm = iot.getBool  ("alarm_on",    false);

// Manage
iot.hasKey("threshold");     // true if the key exists
iot.removeKey("threshold");  // delete one key
iot.clearAllData();          // delete everything you saved

Key names can be at most 15 characters.

Restore outputs after a restart

Save a setting when the user changes it, and restore it at boot:

bool relayOn = false;

void onRelay(bool on) {
  relayOn = on;
  digitalWrite(RELAY_PIN, on);
  iot.saveBool("relay_on", on);
}

void setup() {
  pinMode(RELAY_PIN, OUTPUT);
  relayOn = iot.getBool("relay_on", false);
  digitalWrite(RELAY_PIN, relayOn);   // correct state straight away, even offline

  iot.onSwitch("V8", onRelay);
  iot.begin();
}

Flash memory wears out after very many writes. Save when a value changes, not on every loop.

Restore outputs after a restart​

Restore outputs after a restart