stm32bringup/ledon.c at master · rfivet/stm32bringup · GitHub

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/* ledon.c -- user LED on
** Copyright (c) 2020-2026 Renaud Fivet
*/

/* Memory locations defined by linker script */
void __StackTop( void) ;        /* __StackTop points after end of stack */
void Reset_Handler( void) ;     /* Entry point for execution */

/* Interrupt vector table:
 * 1  Stack Pointer reset value
 * 15 System Exceptions
 * NN Device specific Interrupts
 */
typedef void (*isr_p)( void) ;
isr_p const isr_vector[ 2] __attribute__((section(".isr_vector"))) = {
    __StackTop,
/* System Exceptions */
    Reset_Handler
} ;


typedef volatile unsigned long  register_t ;

/** PERIPH ********************************************************************/

#define CAT( a, b) a##b
#define HEXA( a) CAT( 0x, a)

#define RCC_AHBENR_IOPxEN( h)   (1 << (17 + HEXA( h) - 0xA))

extern struct {
    register_t  cr ;
    register_t  cfgr ;
    register_t  cir ;
    register_t  apb2rstr ;
    register_t  apb1rstr ;
    register_t  ahbenr ;
    register_t  apb2enr ;
    register_t  apb1enr ;
    register_t  bdcr ;
    register_t  csr ;
    register_t  ahbrstr ;
    register_t  cfgr2 ;
    register_t  cfgr3 ;
    register_t  cr2 ;
} rcc ;                     /* 0x40021000 */

typedef struct {
    register_t  moder ;
    register_t  otyper ;
    register_t  ospeedr ;   /* B..F */
    register_t  pupdr ;
    register_t  idr ;
    register_t  odr ;
    register_t  bsrr ;
    register_t  lckr ;
    register_t  afrl ;
    register_t  afrh ;
    register_t  brr ;
} gpio_t ;


/* user LED ON:
    Board       LED_IOP LED_PIN LED_ON
    No LED                      undefined
    V1.1/Baite  a       4       0
    V2.00       a       4       1
    Nucleo      a       5       1
    vcc-gnd     b       1       0
    Discovery   c       8 or 9  1
*/
#define LED_IOP b
#define LED_PIN 1
#define LED_ON  0

#define GPIO( x) CAT( gpio, x)
extern gpio_t   GPIO( LED_IOP) ;    /* gpioa: 0x48000000, gpiob: 0x48000400 */
                                    /* gpioc: 0x48000800                    */

void Reset_Handler( void) {
/* User LED ON */
    rcc.ahbenr |= RCC_AHBENR_IOPxEN( LED_IOP) ; /* Enable IOPx periph */
    GPIO( LED_IOP).moder |= 1 << (LED_PIN * 2) ; /* Output [01], over default 00 */
    /* OTYPER Push-Pull by default */
    /* PxN output default LOW at reset */

#if LED_ON
    GPIO( LED_IOP).odr = 1 << LED_PIN ;        /* set PxN high (User LED) */
#endif

    for( ;;) ;
}

/* end of ledon.c */