STM32 Timer PWM_Output

STM32F10x_StdPeriph_Lib_V3.3.0\Project\STM32F10x_StdPeriph_Examples\TIM\PWM_Output

uint16_t CCR1_Val = 333; //   333/666=0.5   占空比

uint16_t CCR2_Val = 249; // 249/666=0.374

uint16_t CCR3_Val = 166; // 166/666=0.25

uint16_t CCR4_Val = 83;   // 83/666 =0.125

uint16_t PrescalerValue = 0;



/* Private function prototypes -----------------------------------------------*/

void RCC_Configuration(void);

void GPIO_Configuration(void);



/* Private functions ---------------------------------------------------------*/



/**

* [url=home.php?mod=space&uid=247401]@brief[/url]   Main program

* @param None

* @retval None

*/

int main(void)

{

/*!< At this stage the microcontroller clock setting is already configured,

       this is done through SystemInit() function which is called from startup

       file (startup_stm32f10x_xx.s) before to branch to application main.

       To reconfigure the default setting of SystemInit() function, refer to

       system_stm32f10x.c file

     */    

      

/* System Clocks Configuration */

RCC_Configuration();



/* GPIO Configuration */

GPIO_Configuration();



/* -----------------------------------------------------------------------

    TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles:

    The TIM3CLK frequency is set to SystemCoreClock (Hz), to get TIM3 counter

    clock at 24 MHz the Prescaler is computed as following:

     - Prescaler = (TIM3CLK / TIM3 counter clock) - 1

    SystemCoreClock is set to 72 MHz for Low-density, Medium-density, High-density

    and Connectivity line devices and to 24 MHz for Low-Density Value line and

    Medium-Density Value line devices



    The TIM3 is running at 36 KHz: TIM3 Frequency = TIM3 counter clock/(ARR + 1)

                                                  = 24 MHz / 666 = 36 KHz   36036HZ

    TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR)* 100 = 50%

    TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR)* 100 = 37.5%

    TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR)* 100 = 25%

    TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR)* 100 = 12.5%

----------------------------------------------------------------------- */

/* Compute the prescaler value */

PrescalerValue = (uint16_t) (SystemCoreClock / 24000000) - 1;

/* Time base configuration */

TIM_TimeBaseStructure.TIM_Period = 665; //Autoreload value ARR

TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;



TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);



/* PWM1 Mode configuration: Channel1 */

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_Pulse = CCR1_Val; /* Set the Capture Compare Register value CCR1 */

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;



TIM_OC1Init(TIM3, &TIM_OCInitStructure);

// Enables or disables the TIMx peripheral Preload register on CCR1.

TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);



/* PWM1 Mode configuration: Channel2 */

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_Pulse = CCR2_Val;



TIM_OC2Init(TIM3, &TIM_OCInitStructure);



TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);



/* PWM1 Mode configuration: Channel3 */

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_Pulse = CCR3_Val;



TIM_OC3Init(TIM3, &TIM_OCInitStructure);



TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);



/* PWM1 Mode configuration: Channel4 */

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_Pulse = CCR4_Val;



TIM_OC4Init(TIM3, &TIM_OCInitStructure);



TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);



TIM_ARRPreloadConfig(TIM3, ENABLE);



/* TIM3 enable counter */

TIM_Cmd(TIM3, ENABLE);



while (1)

{}

}