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

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/* board.c -- board mapping abstraction
** Copyright (c) 2020-2026 Renaud Fivet
**
** user LED toggled every second
** SysTick interrupt every second
*/

typedef volatile unsigned long  register_t ;

/** CORE **********************************************************************/

extern struct {
    register_t  csr ;
    register_t  rvr ;
    register_t  cvr ;
    register_t  calib ;
} systick ;                 /* 0xE000E010 */


/** 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 a
#define LED_PIN 4
#define LED_ON  1

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


void SysTick_Handler( void) {
#ifdef LED_ON
    GPIO( LED_IOP).odr ^= 1 << LED_PIN ;    /* toggle PxN (User LED) */
#endif
}

int init( void) {
#define CLOCK 8000000   /* By default HCLK == HSI [8MHZ] */

/* SYSTICK */
#if CLOCK > 0x1000000
# define TICKDIV    8
# define TICKSRC    0   /* STK_CSR_CLKSOURCE == HCLK / 8 */
#else
# define TICKDIV    1
# define TICKSRC    4   /* STK_CSR_CLKSOURCE == HCLK */
#endif

    systick.rvr = (CLOCK / TICKDIV) - 1 ;
    systick.cvr = 0 ;
    systick.csr = TICKSRC | 3 ;         /* CLKSOURCE, Interrupt ON, Enable */
    /* SysTick_Handler will execute every 1s from now on */

#ifdef LED_ON
/* 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
    SysTick_Handler() ;
# endif
#endif
    return 0 ;
}

/* end of board.c */