STM32F1 timer share for PWM and interrupt

Question

i'm implementing a project using stm32f101cb microcontroller. I understand that this control have 3 timer in it. TIM2 and TIM4 had been set to encoder mode to capture 2 rotary encoder.

I'm now left me the only timer TIM3, I would to ask is there possible for me to set TIM3 to PWM mode and at the same time doing the normal timer interrupt? I could not find it in reference manual or programming manual.

Thanks!

Answer 1

It should be possible. I'm doing it for an STM32F091RC I've developed an application for where I'm controlling LED:s with PWM and generating a timer update interrupt (counter reset) with the same timer peripheral.

Here's some of my configuration code:

GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
/* LED_TIM clock enable */
RCC_APB1PeriphClockCmd(TIM_LED_RCC, ENABLE);
/* LED_PORT Configuration: Channel 1, 2, 3 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = LED_PIN;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(LED_PORT, &GPIO_InitStructure);
GPIO_PinAFConfig(LED_PORT, LED_PIN_SOURCE, LED_TIM_AF);
/* Enable the TIM global Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = LED_TIM_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 3;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = LED_TIM_PSC;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = 0xFFFF; // Max 0xFFFF
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
/* Channel 1 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
TIM_OCInitStructure.TIM_Pulse = LED_INIT_PULSE;
TIM_OC1Init(LED_TIM, &TIM_OCInitStructure); // Init Channel 1
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Disable);
/* TIM IT enable */
TIM_ITConfig(LED_TIM, TIM_IT_Update, ENABLE); // Enable interrupts for LED_TIM
/* LED_TIM counter enable */
TIM_Cmd(LED_TIM, ENABLE);
/* LED_TIM Main Output Enable */
TIM_CtrlPWMOutputs(LED_TIM, ENABLE);

Should be very similar for your device. If everything works correctly, you should be getting interrupts in your TIM3_IRQHandler ISR

void TIM3_IRQHandler(void)
{
if (TIM_GetITStatus(LED_TIM, TIM_IT_Update) != RESET)
 {
 TIM_ClearITPendingBit(LED_TIM, TIM_IT_Update);
 // Do ISR stuff here!
 }
}