Code examples RM0367
984/1043 RM0367 Rev 7
A.4.3 MCO selection code example
/* (1) Clear the MCO selection bits */
/* (2)Select system clock/4 to be output on the MCO without prescaler */
RCC->CFGR &= (uint32_t) RCC_CFGR_MCOSEL; /* (1) */
RCC->CFGR |= RCC_CFGR_MCO_SYSCLK | RCC_CFGR_MCO_PRE_4; /* (2) */
A.5 GPIOs
A.5.1 Locking mechanism code example
/* (1) Write LCKK bit to 1 and set the pin bits to lock */
/* (2) Write LCKK bit to 0 and set the pin bits to lock */
/* (3) Write LCKK bit to 1 and set the pin bits to lock */
/* (4) Read the Lock register */
/* (5) Check the Lock register (optionnal) */
GPIOA->LCKR = GPIO_LCKR_LCKK + lock; /* (1) */
GPIOA->LCKR = lock; /* (2) */
GPIOA->LCKR = GPIO_LCKR_LCKK + lock; /* (3) */
GPIOA->LCKR; /* (4) */
if ((GPIOA->LCKR & GPIO_LCKR_LCKK) == 0) /* (5) */
{
/* Manage error */
}
A.5.2 Alternate function selection sequence code example
/* (1) Enable the peripheral clock of Timer 2 */
/* (2) Enable the peripheral clock of GPIOA */
/* (3) Select Alternate function mode (10) on GPIOA pin 0 */
/* (4) Select TIM2_CH1 on PA0 by enabling AF2 for pin 0 in GPIOA AFRL
register */
RCC->APB1ENR |= RCC_APB1ENR_TIM2EN; /* (1) */
RCC->IOPENR |= RCC_IOPENR_GPIOAEN; /* (2) */
GPIOA->MODER = (GPIOA->MODER & ~(GPIO_MODER_MODE0)) \
| (GPIO_MODER_MODE0_1); /* (3) */
GPIOA->AFR[0] |= 0x2; /* (4) */
A.5.3 Analog GPIO configuration code example
/* (1) Enable the peripheral clock of GPIOA */
/* (2) Select Input Float (00- default) on GPIOA pin 0 */
RCC->IOPENR |= RCC_IOPENR_GPIOAEN; /* (1) */
GPIOA->MODER &= ~(GPIO_MODER_MODE0); /* (2) */
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