I have made a code for PWM for STM32F407. It is working fine for generating PWM.
1. Currently what happens is I have made a PWM period of 5seconds in total.
2. Suppose in code I call TIM_SetCompare2(TIM9 , 32767), now outout will be 2.5 seconds on & 2.5 seconds off.
where 32767 is 50% duty cycle, & 65535 is 100% duty cycle.
3. Now suppose on time of 2.5seconds is running & I suddenly change TIM_SetCompare2(TIM9 , 10000), it will now be roughly 15% on and 15% off.
This happens even if previous 2.5 duty cycle was running
4. I want that next compare value updates only after completion of first compare match cycle.
5. I have no way to sync both, because compare value is coming from a another setup at random stage, & when a new compare value comes, I have to set a display to user, and it should run for that compare cycle only, not to get updated by new compare cycle.
6. How to do it?
void initialize_pwm(void)
{
uint16_t Channel2Pulse = 0U;
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
/* GPIOA Configuration: Channel 2 as alternate function push-pull */
RCC_AHB1PeriphClockCmd( RCC_AHB1Periph_GPIOA , ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_TIM9);
/* TIM9 clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM9 , ENABLE);
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = 12816U;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = 65535;//PWM_PERIOD_VALUE;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM9, &TIM_TimeBaseStructure);
/* Channel 2 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;
TIM_OCInitStructure.TIM_Pulse = Channel2Pulse;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
TIM_OC2Init(TIM9, &TIM_OCInitStructure);
/* TIM9 counter enable */
TIM_Cmd(TIM9, ENABLE);
/* TIM9 Main Output Enable */
TIM_CtrlPWMOutputs(TIM9, ENABLE);
TIM_SetCompare2(TIM9 , 32767);
} /* function ends here */