TIM8 Toggle STM32F4

[pedro]

Posted on June 26, 2015 at 12:32

Hi,

I'm trying to toggle some pins when timer 8 overflows. The problem I get is that I don´t see the pins toogle but I can see the timer counting on the debugger, so I think I might be missing some mistereous configuration on the GPIO. I'm using all 4 channels just for testing and I put a pulse value of half the timer period for testing aswell. The code I have so far:

void TIM8_Init(void){
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM8 ,ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_High_Speed;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOC,&GPIO_InitStructure);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6 ,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource7 ,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource8 ,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource9 ,GPIO_AF_TIM8);
TIM_TimeBaseStructure.TIM_Period = 100; 
TIM_TimeBaseStructure.TIM_Prescaler = 0; 
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM8, &TIM_TimeBaseStructure);
//Channel 1
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;
TIM_OCInitStructure.TIM_Pulse = 50;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;
TIM_OC1Init(TIM8, &TIM_OCInitStructure);
TIM_OC2Init(TIM8, &TIM_OCInitStructure);
TIM_OC3Init(TIM8, &TIM_OCInitStructure);
TIM_OC4Init(TIM8, &TIM_OCInitStructure);
//TIM_DMACmd(TIM8, TIM_DMA_Update, ENABLE ); /* Enable TIM8_Updates DMA Requests */
//SET COUNTER
TIM8->CR1 = 0x1; 
}

Thanks :)

[kai_mauer]

Posted on June 26, 2015 at 15:36

You write:
 

GPIO_Init(GPIOC,&GPIO_InitStructure);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6 ,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource7 ,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource8 ,GPIO_AF_TIM8);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource9 ,GPIO_AF_TIM8);
 This itches me a little. Wrong order?
 First I would config the pins, then do GPIO_Init().
 I use HAL, so I explicitly cannot say whether the order is right or wrong. The HAL function set all regs at once...
 Have you looked in the GPIO AF reg with the debugger? 

[Tesla DeLorean]

Posted on June 26, 2015 at 15:43

Not sure the pin ordering matters, provided the GPIO clock is enabled, it's pins/mux are configurable.

  /* TIM8 (special) enable pins */

  TIM_CtrlPWMOutputs(TIM8, ENABLE);

  /* TIM8 enable counter */

  TIM_Cmd(TIM8, ENABLE);

[pedro]

Posted on July 01, 2015 at 22:57

Thanks clive1!

I knew it had to be something simple that I was missing.