low-power-embedded

Name: low-power-embedded
Author: mohitmishra786

141stars19forks

How to install low-power-embedded?

mohitmishra786/low-level-dev-skills/low-power-embedded

$npx -y skills add mohitmishra786/low-level-dev-skills --skill low-power-embedded

Installs into the current project.

Summary

Low-power embedded skill for sleep modes and energy optimization. Use when configuring MCU sleep/stop/standby, peripheral clock gating, wake-up sources, or measuring firmware current draw. Activates on queries about WFI, STOP mode, STM32 PWR, nRF sleep, wake-up EXTI, or reducing

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SKILL.md

1	# Low-Power Embedded
2
3	## Purpose
4
5	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).
6
7	## When to Use
8
9	- Battery-powered firmware missing power budget
10	- Wake-up latency vs consumption tradeoffs
11	- Debugging "device won't wake" or "current still mA in sleep"
12	- Before shipping RTOS idle hook or bare-metal main loop sleep
13	- Cross-linking with `skills/baremetal/interrupts-and-exceptions-baremetal`
14
15	## Workflow
16
17	### 1. Power mode hierarchy (STM32-style)
18
19	\| Mode \| CPU \| Peripherals \| RAM \| Wake source \| Relative current \|
20	\|------\|-----\|-------------\|-----\|-------------\|------------------\|
21	\| Run \| on \| on \| on \| — \| highest \|
22	\| Sleep \| off \| on \| on \| any IRQ \| medium \|
23	\| Stop \| off \| most off \| on \| EXTI, RTC, UART \| low \|
24	\| Standby \| off \| off \| lost* \| WKUP pins, RTC \| lowest \|
25
26	\* Standby clears most SRAM; use backup domain or external EEPROM for state.
27
28	### 2. Enter Sleep (WFI)
29
30	```c
31	/* Cortex-M — sleep until interrupt */
32	__disable_irq();
33	/* configure wake source (e.g. EXTI, RTC alarm) */
34	__enable_irq();
35	__WFI(); /* or __WFE() for event-based wake */
36	```
37
38	Ensure pending interrupts are cleared before `WFI` or wake may be immediate.
39
40	### 3. STM32 Stop mode pattern
41
42	```c
43	#include "stm32f4xx.h"
44
45	void enter_stop_mode(void)
46	{
47	/* Gate clocks you do not need */
48	RCC->AHB1ENR &= ~RCC_AHB1ENR_GPIOAEN; /* example — only if safe */
49
50	PWR->CR \|= PWR_CR_CWUF; /* clear wake flags */
51	PWR->CR \|= PWR_CR_PDDS; /* deep sleep = Stop */
52	SCB->SCR \|= SCB_SCR_SLEEPDEEP_Msk;
53
54	__WFI();
55
56	/* After wake: re-enable HSE/PLL — clocks lost in Stop on many parts */
57	SystemInit();
58	}
59	```
60
61	After Stop, re-init clocks and peripherals that lost their registers.
62
63	### 4. Clock gating checklist
64
65	```
66	Before sleep
67	├── Disable unused peripheral clocks (RCC xENR)
68	├── Disable ADC/DAC continuous modes
69	├── Stop DMA channels
70	├── Enter peripheral low-power (UART mute, SPI off)
71	└── Configure lowest viable regulator scale (Voltage Scale 2/3)
72	```
73
74	### 5. Wake-up sources
75
76	\| Source \| Config \|
77	\|--------\|--------\|
78	\| EXTI GPIO \| SYSCFG + EXTI IMR, edge trigger \|
79	\| RTC alarm \| RTC WUT/WAKEUP \|
80	\| UART \| Start bit detection (some MCUs) \|
81	\| IWDG \| Not a wake source — resets device \|
82
83	### 6. Measurement tips
84
85	- Use ammeter in series with VDDA/VDD; short sampling window for uA
86	- DWT cycle counter for wake latency benchmarking
87	- Compare run vs sleep current with same clock tree documented
88
89	### 7. RTOS note
90
91	FreeRTOS `configUSE_TICKLESS_IDLE` maps to WFI/Stop — coordinate with `skills/embedded/freertos`.
92
93	### 8. Agent usage
94
95	```
96	/low-power-embedded Configure STM32 Stop mode with EXTI0 wake and PLL restore
97	```
98
99	## Common Problems
100
101	\| Symptom \| Cause \| Fix \|
102	\|---------\|-------\|-----\|
103	\| Still mA in "sleep" \| Debug interface active (SWD) \| Disconnect debugger; disable DBGMCU \|
104	\| Immediate wake from WFI \| Pending NVIC IRQ \| Clear flags before WFI \|
105	\| Lost state after wake \| Entered Standby not Stop \| Use Stop if RAM must persist \|
106	\| UART dead after wake \| Clock tree not restored \| Call `SystemInit()` path \|
107	\| Higher than datasheet uA \| Floating GPIO \| Set unused pins analog or pull \|
108
109	## Related Skills
110
111	- `skills/baremetal/interrupts-and-exceptions-baremetal` — EXTI wake IRQs
112	- `skills/baremetal/gpio-baremetal` — pin mode for leakage control
113	- `skills/baremetal/stm32-baremetal` — RCC and PWR registers
114	- `skills/baremetal/timers-pwm-baremetal` — stop timers before sleep
115	- `skills/embedded/freertos` — tickless idle integration

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Type

low-power-embedded

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View on GitHub

How to install low-power-embedded?

mohitmishra786/low-level-dev-skills/low-power-embedded

$npx -y skills add mohitmishra786/low-level-dev-skills --skill low-power-embedded

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Low-Power Embedded
2
3	## Purpose
4
5	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).
6
7	## When to Use
8
9	- Battery-powered firmware missing power budget
10	- Wake-up latency vs consumption tradeoffs
11	- Debugging "device won't wake" or "current still mA in sleep"
12	- Before shipping RTOS idle hook or bare-metal main loop sleep
13	- Cross-linking with `skills/baremetal/interrupts-and-exceptions-baremetal`
14
15	## Workflow
16
17	### 1. Power mode hierarchy (STM32-style)
18
19	\| Mode \| CPU \| Peripherals \| RAM \| Wake source \| Relative current \|
20	\|------\|-----\|-------------\|-----\|-------------\|------------------\|
21	\| Run \| on \| on \| on \| — \| highest \|
22	\| Sleep \| off \| on \| on \| any IRQ \| medium \|
23	\| Stop \| off \| most off \| on \| EXTI, RTC, UART \| low \|
24	\| Standby \| off \| off \| lost* \| WKUP pins, RTC \| lowest \|
25
26	\* Standby clears most SRAM; use backup domain or external EEPROM for state.
27
28	### 2. Enter Sleep (WFI)
29
30	```c
31	/* Cortex-M — sleep until interrupt */
32	__disable_irq();
33	/* configure wake source (e.g. EXTI, RTC alarm) */
34	__enable_irq();
35	__WFI(); /* or __WFE() for event-based wake */
36	```
37
38	Ensure pending interrupts are cleared before `WFI` or wake may be immediate.
39
40	### 3. STM32 Stop mode pattern
41
42	```c
43	#include "stm32f4xx.h"
44
45	void enter_stop_mode(void)
46	{
47	/* Gate clocks you do not need */
48	RCC->AHB1ENR &= ~RCC_AHB1ENR_GPIOAEN; /* example — only if safe */
49
50	PWR->CR \|= PWR_CR_CWUF; /* clear wake flags */
51	PWR->CR \|= PWR_CR_PDDS; /* deep sleep = Stop */
52	SCB->SCR \|= SCB_SCR_SLEEPDEEP_Msk;
53
54	__WFI();
55
56	/* After wake: re-enable HSE/PLL — clocks lost in Stop on many parts */
57	SystemInit();
58	}
59	```
60
61	After Stop, re-init clocks and peripherals that lost their registers.
62
63	### 4. Clock gating checklist
64
65	```
66	Before sleep
67	├── Disable unused peripheral clocks (RCC xENR)
68	├── Disable ADC/DAC continuous modes
69	├── Stop DMA channels
70	├── Enter peripheral low-power (UART mute, SPI off)
71	└── Configure lowest viable regulator scale (Voltage Scale 2/3)
72	```
73
74	### 5. Wake-up sources
75
76	\| Source \| Config \|
77	\|--------\|--------\|
78	\| EXTI GPIO \| SYSCFG + EXTI IMR, edge trigger \|
79	\| RTC alarm \| RTC WUT/WAKEUP \|
80	\| UART \| Start bit detection (some MCUs) \|
81	\| IWDG \| Not a wake source — resets device \|
82
83	### 6. Measurement tips
84
85	- Use ammeter in series with VDDA/VDD; short sampling window for uA
86	- DWT cycle counter for wake latency benchmarking
87	- Compare run vs sleep current with same clock tree documented
88
89	### 7. RTOS note
90
91	FreeRTOS `configUSE_TICKLESS_IDLE` maps to WFI/Stop — coordinate with `skills/embedded/freertos`.
92
93	### 8. Agent usage
94
95	```
96	/low-power-embedded Configure STM32 Stop mode with EXTI0 wake and PLL restore
97	```
98
99	## Common Problems
100
101	\| Symptom \| Cause \| Fix \|
102	\|---------\|-------\|-----\|
103	\| Still mA in "sleep" \| Debug interface active (SWD) \| Disconnect debugger; disable DBGMCU \|
104	\| Immediate wake from WFI \| Pending NVIC IRQ \| Clear flags before WFI \|
105	\| Lost state after wake \| Entered Standby not Stop \| Use Stop if RAM must persist \|
106	\| UART dead after wake \| Clock tree not restored \| Call `SystemInit()` path \|
107	\| Higher than datasheet uA \| Floating GPIO \| Set unused pins analog or pull \|
108
109	## Related Skills
110
111	- `skills/baremetal/interrupts-and-exceptions-baremetal` — EXTI wake IRQs
112	- `skills/baremetal/gpio-baremetal` — pin mode for leakage control
113	- `skills/baremetal/stm32-baremetal` — RCC and PWR registers
114	- `skills/baremetal/timers-pwm-baremetal` — stop timers before sleep
115	- `skills/embedded/freertos` — tickless idle integration

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Type