low-power-embedded

사용 방법

설치 명령을 복사하고 자신의 에이전트 환경에 설치하기 전에 소스 패키지를 확인하세요.
필요한 도구, 인증 정보, 지원 환경은 원본 문서에서 확인하세요.
입력과 원하는 산출물을 설명하고 출처와 결과를 대조하세요.

npx skills add https://github.com/mohitmishra786/low-level-dev-skills --skill low-power-embedded

시작 전 확인

설치에는 모델 구독, API 한도, 파일 접근 권한이 포함되지 않습니다.
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원본 Skill 문서

원본 저장소의 제목, 예시, 코드, 표, 링크, 이미지를 유지해 표시합니다.

Low-Power Embedded

Purpose

Guide agents through MCU low-power modes: sleep vs deep sleep (stop/standby), peripheral and bus clock gating, wake-up source configuration, and practical current measurement — with Cortex-M WFI/WFE and vendor PWR examples (STM32-focused patterns apply broadly).

When to Use

Battery-powered firmware missing power budget
Wake-up latency vs consumption tradeoffs
Debugging "device won't wake" or "current still mA in sleep"
Before shipping RTOS idle hook or bare-metal main loop sleep
Cross-linking with skills/baremetal/interrupts-and-exceptions-baremetal

Workflow

1. Power mode hierarchy (STM32-style)

Mode	CPU	Peripherals	RAM	Wake source	Relative current
Run	on	on	on	—	highest
Sleep	off	on	on	any IRQ	medium
Stop	off	most off	on	EXTI, RTC, UART	low
Standby	off	off	lost*	WKUP pins, RTC	lowest

\* Standby clears most SRAM; use backup domain or external EEPROM for state.

2. Enter Sleep (WFI)

/* Cortex-M — sleep until interrupt */
__disable_irq();
/* configure wake source (e.g. EXTI, RTC alarm) */
__enable_irq();
__WFI(); /* or __WFE() for event-based wake */

Ensure pending interrupts are cleared before WFI or wake may be immediate.

3. STM32 Stop mode pattern

#include "stm32f4xx.h"

void enter_stop_mode(void)
{
    /* Gate clocks you do not need */
    RCC->AHB1ENR &= ~RCC_AHB1ENR_GPIOAEN; /* example — only if safe */

    PWR->CR |= PWR_CR_CWUF;   /* clear wake flags */
    PWR->CR |= PWR_CR_PDDS;   /* deep sleep = Stop */
    SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;

    __WFI();

    /* After wake: re-enable HSE/PLL — clocks lost in Stop on many parts */
    SystemInit();
}

After Stop, re-init clocks and peripherals that lost their registers.

4. Clock gating checklist

Before sleep
├── Disable unused peripheral clocks (RCC xENR)
├── Disable ADC/DAC continuous modes
├── Stop DMA channels
├── Enter peripheral low-power (UART mute, SPI off)
└── Configure lowest viable regulator scale (Voltage Scale 2/3)

5. Wake-up sources

Source	Config
EXTI GPIO	SYSCFG + EXTI IMR, edge trigger
RTC alarm	RTC WUT/WAKEUP
UART	Start bit detection (some MCUs)
IWDG	Not a wake source — resets device

6. Measurement tips

Use ammeter in series with VDDA/VDD; short sampling window for uA
DWT cycle counter for wake latency benchmarking
Compare run vs sleep current with same clock tree documented

7. RTOS note

FreeRTOS configUSE_TICKLESS_IDLE maps to WFI/Stop — coordinate with skills/embedded/freertos.

8. Agent usage

/low-power-embedded Configure STM32 Stop mode with EXTI0 wake and PLL restore

Common Problems

Symptom	Cause	Fix
Still mA in "sleep"	Debug interface active (SWD)	Disconnect debugger; disable DBGMCU
Immediate wake from WFI	Pending NVIC IRQ	Clear flags before WFI
Lost state after wake	Entered Standby not Stop	Use Stop if RAM must persist
UART dead after wake	Clock tree not restored	Call `SystemInit()` path
Higher than datasheet uA	Floating GPIO	Set unused pins analog or pull

Related Skills

skills/baremetal/interrupts-and-exceptions-baremetal — EXTI wake IRQs
skills/baremetal/gpio-baremetal — pin mode for leakage control
skills/baremetal/stm32-baremetal — RCC and PWR registers
skills/baremetal/timers-pwm-baremetal — stop timers before sleep
skills/embedded/freertos — tickless idle integration