Low-Power & Deep Sleep Architecture

Energy Consumption Profile

In standard active mode, the ESP32 with LCD backlight draws approximately 80–120 mA. Operating continuously on a 2000 mAh LiPo battery would drain the device in less than a day.

Deep Sleep Strategy

Kitchen occupancy is intermittent. The device employs a strict power budget:

1. When motion stops, a 20-second countdown initiates (NO_MOTION_TIMEOUT_S = 20).
2. When the timer expires:
   • LCD backlight is deactivated: lcd.noBacklight().
   • ESP32 enters deep sleep: esp_deep_sleep_start().
3. In deep sleep mode:
   • The main dual-core CPU is completely powered down.
   • High-speed peripherals are turned off.
   • Current draw drops into microamps (~10–15 µA for RTC domain).
   • Only the PIR sensor and RTC wakeup pin (GPIO 34) remain energized.