测试程序如下：
#include "stm8s.h"
void CLK_Init(void)
{
/* Configure clock prescaler */
CLK->CKDIVR = 0x01; /* To be programmed with different value */
/* Fmaster, Fmaster/1, ... */
/* To select external source by automtic switch */
CLK->SWCR |= 0x02; /* Enable switch */
CLK->SWR = 0xB4; /* Select HSE */
while (!(CLK->SWCR & 0x08)); /* Wait for switch done */
/* verify the external clock is selected (optional) */
if (CLK->CMSR != 0xB4)
while(1);
CLK->CSSR |= 0x01;
}
/* Private defines -----------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
#define LEDS_PORT (GPIOD)
#define LED1_PIN (GPIO_PIN_0)
#define LED2_PIN (GPIO_PIN_2)
#define LED3_PIN (GPIO_PIN_3)
void Delay(u16 nCount)
{
/* Decrement nCount value */
while (nCount != 0)
{
nCount--;
}
}
int main(void)
{
u8 Leds = LED1_PIN|LED2_PIN|LED3_PIN; /* Contains which LEDs to operate */
u8 t = 10;
/* Initialize I/Os in Output Mode */
GPIO_Init(LEDS_PORT, (LED1_PIN | LED2_PIN | LED3_PIN ), GPIO_MODE_OUT_PP_LOW_FAST);
// 这里是用启动后默认的16MHz(HSI)/8=2MHz时钟工作
while (t--)
{
/* LEDs ON */
GPIO_WriteHigh(LEDS_PORT, Leds);
Delay((u16)60000);
Delay((u16)60000);
/* LEDs OFF */
GPIO_WriteLow(LEDS_PORT, Leds);
Delay((u16)60000);
Delay((u16)60000);
}
CLK_Init();
t=10;
// 切换到HSE 24MHz晶振，FCPU＝FMASTER/2，正常工作，LED闪烁变快了
while (t--)
{
/* LEDs ON */
GPIO_WriteHigh(LEDS_PORT, Leds);
Delay((u16)60000);
Delay((u16)60000);
/* LEDs OFF */
GPIO_WriteLow(LEDS_PORT, Leds);
Delay((u16)60000);
Delay((u16)60000);
}
CLK->CKDIVR = 0X00;
// 切换到FCPU＝FMASTER/1 24MHz，不工作，看上去是很快系统复位了。
while (1)
{
/* LEDs ON */
GPIO_WriteHigh(LEDS_PORT, Leds);
Delay((u16)60000);
Delay((u16)60000);
/* LEDs OFF */
GPIO_WriteLow(LEDS_PORT, Leds);
Delay((u16)60000);
Delay((u16)60000);
}
}
实验板是STM8 MINI KIT |
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