Вот так шибчЕе - порядка 12 МГц... int main(void)
{
uint32_t u32High = 0x00000001;
uint32_t u32Low = 0x00010000;
SET_BIT(RCC->IOPENR,RCC_IOPENR_GPIOAEN); // разрешим GPIOA
MODIFY_REG(GPIOA->MODER, GPIO_MODER_MODE0_1,GPIO_MODER_MODE0_0); // PIN A0 на выход
while(1)
{
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
GPIOA->BSRR = u32High;
GPIOA->BSRR = u32Low;
}
}