Posted on June 25, 2014 at 09:31Hello guys i m New to STM32 , i m using Keil ARM tools.
I have written LED Blinky code with STM32F051C8 the following code .In the below code if i change RCC_CFGR_PLLMULL2 to RCC_CFGR_PLLMULLX(X=3,4,6....12) My LED blinky code is not working where as its working fine for PLLMULL2 .....
help me guys why it is happening ...?
#include ''stm32f0xx.h'' // Device header
#include <stdio.h>
void SystemCoreClockSetHSI(void) {
RCC->CR |= ((uint32_t)RCC_CR_HSION); /* Enable HSI */
while ((RCC->CR & RCC_CR_HSIRDY) == 0); /* Wait for HSI Ready */
RCC->CFGR = RCC_CFGR_SW_HSI; /* HSI is system clock */
while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_HSI); /* Wait for HSI used as system clock */
FLASH->ACR = FLASH_ACR_PRFTBE; /* Enable Prefetch Buffer */
FLASH->ACR |= FLASH_ACR_LATENCY; /* Flash 1 wait state */
RCC->CFGR |= RCC_CFGR_HPRE_DIV1; /* HCLK = SYSCLK */
RCC->CFGR |= RCC_CFGR_PPRE_DIV1; /* PCLK = HCLK */
RCC->CR &= ~RCC_CR_PLLON; /* Disable PLL */
/* PLL configuration: = HSI/2 * 12 = 48 MHz */
RCC->CFGR &= ~(RCC_CFGR_PLLSRC | RCC_CFGR_PLLXTPRE | RCC_CFGR_PLLMULL);
RCC->CFGR |= (RCC_CFGR_PLLSRC_HSI_Div2 | RCC_CFGR_PLLMULL2);
RCC->CR |= RCC_CR_PLLON; /* Enable PLL */
while((RCC->CR & RCC_CR_PLLRDY) == 0) __NOP(); /* Wait till PLL is ready */
RCC->CFGR &= ~RCC_CFGR_SW; /* Select PLL as system clock source */
RCC->CFGR |= RCC_CFGR_SW_PLL;
while ((RCC->CFGR & RCC_CFGR_SWS) != RCC_CFGR_SWS_PLL); /* Wait till PLL is system clock src */
}
void LED_on(void)
{
GPIOB->BSRR |= (1 << 11);
}
void LED_off(void)
{
GPIOB->BSRR |= (1 << 27);
}
void Delay(unsigned int time) {
volatile unsigned int i,j;
for(i=0;i<time;i++)
for(j=0;j<1000;j++);
}
/*
* main: initialize and start the system
*/
int main (void) {
SystemCoreClockSetHSI();
SystemCoreClockUpdate ();
RCC->AHBENR |= (1 << 18); /* Enable GPIOB clock */
/* Configure (PB.11,) pins as push-pull outputs, No pull-up, pull-down */
GPIOB->MODER &= ~((3 << 2*11));
GPIOB->MODER |= ((1 << 2*11));
GPIOB->OTYPER &= ~((3 << 11));
GPIOB->OSPEEDR &= ~((3 << 2*11));
GPIOB->OSPEEDR |= ((3 << 2*11));
GPIOB->PUPDR &= ~((3 << 2*11));
while(1)
{
LED_on(); Delay(1000);
LED_off(); Delay(1000);
}
}
