Mode d’emploi
- Copiez la commande et examinez le paquet avant de l’installer dans votre environnement agent.
- Consultez le document original pour les outils, identifiants et environnements requis.
- Décrivez les entrées et le livrable souhaité ; comparez la sortie aux sources.
npx skills add https://github.com/mohitmishra786/low-level-dev-skills --skill gpio-baremetalAvant de commencer
- L’installation n’inclut ni abonnement au modèle, ni quota API, ni accès aux fichiers.
- Étoiles et installations reflètent l’activité, pas un test indépendant de qualité ou de sécurité.
Document Skill original
Rendu depuis le dépôt source en conservant titres, exemples, code, tableaux, liens et images.
GPIO (Bare-Metal)
Purpose
Configure and use GPIO without HAL: input/output modes, alternate function mapping, pull-up/down, speed/slew, and pin-change interrupts for LEDs, buttons, and peripheral pin mux.
When to Use
- Blink LED or read button before bringing up UART/SPI
- Mux pins to USART/SPI alternate functions
- EXTI line interrupts on pin edges
- Porting GPIO code between vendors
Workflow
1. STM32 GPIO pattern
c
/* Enable GPIOA clock */
RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
/* PA5 output — MODER[11:10] = 01 */
GPIOA->MODER &= ~(3U << (5 * 2));
GPIOA->MODER |= (1U << (5 * 2));
/* Toggle via BSRR — atomic set/reset */
GPIOA->BSRR = (1U << 5); /* set */
GPIOA->BSRR = (1U << (5+16)); /* reset */Alternate function (e.g., USART2 TX on PA2):
c
GPIOA->MODER &= ~(3U << (2*2));
GPIOA->MODER |= (2U << (2*2)); /* AF mode */
GPIOA->AFR[0] &= ~(0xFU << (2*4));
GPIOA->AFR[0] |= (7U << (2*4)); /* AF7 = USART2 */2. Input with pull-up
c
/* PC13 input, pull-up */
GPIOC->MODER &= ~(3U << (13*2)); /* input mode 00 */
GPIOC->PUPDR &= ~(3U << (13*2));
GPIOC->PUPDR |= (1U << (13*2)); /* pull-up */
int pressed = !(GPIOC->IDR & (1U << 13)); /* active low */3. EXTI interrupt (STM32)
c
/* SYSCFG: map EXTI13 to PC13 */
SYSCFG->EXTICR[3] = (SYSCFG->EXTICR[3] & ~0xFU) | 0x2; /* port C */
EXTI->IMR |= (1U << 13);
EXTI->FTSR |= (1U << 13); /* falling edge */
NVIC_EnableIRQ(EXTI15_10_IRQn);ISR: check EXTI->PR, clear with write-1.
4. nRF52 / ESP32 notes
| Platform | Pattern |
|---|---|
| nRF52 | NRF_P0->PIN_CNF[n] — direction, pull, drive |
| ESP32 | GPIO.out_w1ts, GPIO.enable; IO_MUX for function |
Always enable peripheral clock / power domain before pin config.
5. Agent usage
/gpio-baremetal Configure PA2 as USART2 TX alternate function on STM32F4Common Problems
| Symptom | Cause | Fix |
|---|---|---|
| Pin stuck | Wrong MODER / not AF | Re-read RM pin table |
| EXTI storm | No debounce / floating input | Enable pull; debounce in software |
| AF mismatch | Wrong AFR nibble | Pin-specific AF table in RM |
| No toggle visible | Wrong port bit / LED active low | Check schematic |
Related Skills
skills/baremetal/mmio-and-bit-manipulation— BSRR/MODER masksskills/baremetal/peripherals-from-datasheet— RM pinout tablesskills/baremetal/uart-serial-baremetal— AF mux for serial
