You can add to Samovar a button or a sensor (for example, a water leak sensor) that works by closing a contact. The input depends on the board: GPIO35 on ESP32 DEVKIT, GPIO48 on ESP32-S3. The emergency button is not supported on LILYGO boards.
When a low level is applied to the input (a short to ground), Samovar performs an emergency stop: it turns off heating and puts the voltage regulator into sleep mode, closes the valve and stops the water supply, stops the take-off pump, the stirrer and the I2CStepper dosing pump, sounds the buzzer and sends the message "Emergency shutdown: the emergency button is pressed" («Аварийное отключение: нажата аварийная кнопка»). You can connect the button and several sensors in parallel. The only requirement is that the sensors are rated for 3.3V. The emergency mode can be exited only by a reboot. If the button is pressed (the sensor is closed) when the power is switched on, Samovar goes into emergency mode right after startup.
Warning. On ESP32 DEVKIT the GPIO35 input has no internal pull-up, so an external resistor (10 kOhm) between the input and 3.3V is required. ESP32-S3 uses an internal pull-up, so no external resistor is needed.
The button is disabled by default. Samovar 7.00: the button is enabled on the "Equipment" («Оборудование») tab of the configurator (the "Use the emergency button" («Использовать аварийную кнопку») checkbox); in PlatformIO there is a ready-made environment Samovar_alarm_button for this. If you configure it manually, in the file Samovar_ini.h you need to replace
