Cómo utilizar un temporizador universal de STM32 para generar PWM con frecuencia ajustable

void TIM2_PWM_OUT_Conf(void)

{

RCC-gt;APB1ENR |=1lt;lt;0 //Reloj TIM2

RCC-gt;APB2ENR |=1lt;lt;2; //Reloj GPA

RCC-gt;APB2ENR |=1lt;lt;0; //Reloj AFIO

RCC -gt;APB2ENR |=1lt;lt;3; //Reloj GPB

RCC-gt;APB1ENR |=7lt;lt;0; //Reloj TIM2 TIM3 TIM4

GPIOA -gt;CRL amp;=0xFFFF0000; //

GPIOA-gt;CRL |=0x0000BBBB; //Salida AF

TIM2-gt;CR1 |=1lt;lt; 4; //Cuenta atrás

TIM2-gt;CCMR1 |=6lt;lt;4; //OC1M: PWM1

TIM2-gt;CCMR1 |=6lt;lt;12 ; //OC2M: PWM1

TIM2-gt;CCMR2 |=6lt;lt;4; //OC3M: PWM1

TIM2-gt;CCMR2 |=6lt;lt;12 ; //OC4M: PWM1

// TIM2-gt;CCMR1 |=1lt;lt;2;

// TIM2-gt;CCMR2 |=1lt;lt;10;

// TIM2-gt;CCMR1 |=1lt;lt;2;

// TIM2-gt;CCMR2 |=1lt;lt;10;

TIM2-gt;CCER |=1lt;lt;0; //CC1E HABILITADO

TIM2-gt;CCER |=1lt;lt;4; //CC2E HABILITADO

TIM2 -gt;CCER |=1lt;lt;8; //CC3E HABILITADO

TIM2-gt;CCER |=1lt;lt;12; //CC4E HABILITADO

TIM2-gt ;PSC =719; //720-1 PSC

TIM2-gt; ARR =PWM_PERIOD; //20ms

TIM2-gt;CR1 |=1lt;lt;0; /ENABLE

}

//El registro CCR modifica el ciclo de trabajo