• ESP-IDF recommended for the remote because it provides direct deep-sleep, GPIO wake, ADC calibration, and ESP-NOW control.
• ESPHome may be used on the gateway if its ESP-NOW integration meets the event/latency requirements; otherwise use ESP-IDF or Arduino-ESP32 and publish to Home Assistant through MQTT/API.

1. Read wake cause immediately.
2. Configure LED off before other application initialization.
3. Configure GPIO3 input with pull-up and active-low semantics.
4. Sample GPIO3 over the press window to classify single/double/multi/long press.
5. Initialize ADC calibration, delay for the 100 nF divider node, average several GPIO0 samples, and convert by the measured divider ratio.
6. Initialize ESP-NOW, transmit event with sequence number and battery value, wait briefly for acknowledgement, and retry within the latency/energy budget.
7. Return LED off, configure GPIO wake on the paddle level, and enter deep sleep.

1. Initialize status LED off.
2. Start Wi-Fi in station mode and connect to the configured network.
3. Initialize ESP-NOW on the Wi-Fi channel used by the gateway connection.
4. Register receive callback, validate sender identity and sequence number, acknowledge promptly, then publish the event to Home Assistant.
5. Maintain duplicate suppression and expose remote battery state.

C
// Remote GPIO roles
#define PIN_PADDLE   GPIO_NUM_3
#define PIN_LED      GPIO_NUM_1
#define PIN_BAT_ADC  ADC_CHANNEL_0   // GPIO0 / ADC1_CH0

// Active-low wake; select the GPIO wake API supported by the installed ESP-IDF release.
gpio_config_t in = {
  .pin_bit_mask = 1ULL << PIN_PADDLE,
  .mode = GPIO_MODE_INPUT,
  .pull_up_en = GPIO_PULLUP_ENABLE,
};
gpio_config(&in);

C
// LED defaults off
#define PIN_LED GPIO_NUM_1
gpio_set_direction(PIN_LED, GPIO_MODE_OUTPUT);
gpio_set_level(PIN_LED, 0);