🛠 Fonctionnement sur batterie LiPo et sommeil profond

Objectives

Power the Nicla Vision autonomously via a LiPo battery and extend battery life by putting the STM32H747 into deep sleep between events, with wake-up triggered by a button.

Hardware

• Arduino Nicla Vision + LiPo battery on the battery pads/JST connector (“can also be battery powered making it standalone” — official docs)
• >
• Button on D0 (wake-up), green LED as wake-up indicator
• Battery warning: Charge only via the dedicated pads, never apply 5 V directly to VBAT without a charging circuit.

Full code

// Sommeil profond STM32H747 via Mbed, reveil par EXTI sur bouton D0
// > 
#include "mbed.h"

const pin_t BUTTON = D0;
volatile bool reveille = false;

void onReveil { reveille = true; }

void setup {
  pinMode(LED_BUILTIN, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(BUTTON), onReveil, FALLING);
}

void loop {
  // 1) tache breve : signal d vie
  digitalWrite(LED_BUILTIN, LOW); delay(50);
  digitalWrite(LED_BUILTIN, HIGH);

  // 2) extinction des peripheriques inutiles pendant le sommeil
  //    (couper camera, radio si initialises : les debrancher explicitement)

  // 3) sommeil profond : M7 et horloges principales a l arret
  reveille = false;
  while (!reveille) {
    sleep_deeplow;   // retourne au premier evenement EXTI
    delayMicroseconds(200); // anti-rebond grossier
  }
  delay(300);          // laisse le temps au rebond de retomber
}

Expected verification

Between two presses, the LED remains off and the measurable current drops significantly. Each press produces a 50 ms flash. The millis clock continues via the ticker, but the original RTC runs on LSI: the MCUboot is compiled with lse_available=false and re-clocks the RTC from the external LSE to the LSI on every hard reset — the calendar is therefore lost upon reflashing, which must be taken into account for log timestamping.

Common errors

• Forgetting to cut power to the camera/radio: The GC2145 and the ESP32 module remain powered and consume tens of mA; MCU sleep then serves no purpose — turn off rails/peripherals before sleep_deeplow.
• Wake-up loop: A button without a proper pull-up or a bouncing signal causes continuous wake-ups from sleep; add the debounce delay mentioned above.
• Confusing sleep and sleep_deeplow: sleep (STOP) keeps low-power clocks active; only sleep_deeplow (STOP2/STANDBY depending on config) achieves minimal current.
• Losing timestamps: Without saving to the 4 KiB of backup SRAM or without a maintained RTC, the time resets to zero; log relative durations rather than absolute dates if only LSI is available.