Hi,
I am trying to toggle 3 LEDs at rates of 30kHz, 35KHz and 40KHz. I am configuring the TIM4 for this purpose. I am using OC mode -Toggle for doing this.
When I connect Timer Channel pins to OScilloscope, I always see around 12.5Hz instead of the frequencies I configured. I am not sure if I am doing something
wrong here..
My SystemCoreClock is at 72MHZ and APB1 which drives TIM4 is at 36MHZ.
void Timer_CH_Toggle_Setup(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD | RCC_APB2Periph_AFIO, ENABLE );
RCC_APB1PeriphClockCmd( RCC_APB1Periph_TIM4, ENABLE );
GPIO_StructInit(&GPIO_InitStructure); // Reset init structure
/* Remap PD13-15 to TIM4_CH2 to TIM2_CH4 respectively */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; // Alt Function - Push Pull
GPIO_Init( GPIOD, &GPIO_InitStructure );
GPIO_PinRemapConfig( GPIO_Remap_TIM4, ENABLE );
TIM_TimeBaseStructInit( &TIM_TimeBaseStructure );
/* Prescaler Calculation: APB1 - 36MHZ
TIM3 clock should be 840kHz. So, (36MHz/840KHz) = 43
*/
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 65535;
TIM_TimeBaseStructure.TIM_Prescaler = 43-1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit( TIM4, &TIM_TimeBaseStructure );
/* Output Compare Toggle Mode configuration: Channel4 */
/* 840khz/28 = 30 khz */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 28;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
TIM_OC4Init( TIM4, &TIM_OCInitStructure );
TIM_OC4PreloadConfig(TIM4, TIM_OCPreload_Disable);
/* Channel 3 configuration - 840kHz/24 = 35kHZ */
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 24;
TIM_OC3Init( TIM4, &TIM_OCInitStructure );
TIM_OC3PreloadConfig(TIM4, TIM_OCPreload_Disable);
/* Channel 4 configuration - 840kHz/21 = 40 khz */
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 21;
TIM_OC2Init( TIM4, &TIM_OCInitStructure );
TIM_OC2PreloadConfig(TIM4, TIM_OCPreload_Disable);
TIM_Cmd( TIM4, ENABLE );
/* TIM IT enable */
TIM_ITConfig(TIM4, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
/* Enable the TIM3 global Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
return;
}
void TIM4_IRQHandler(void)
{
/* TIM3_CH2 toggling with frequency = 366.2 Hz */
if (TIM_GetITStatus(TIM3, TIM_IT_CC2) != RESET)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);
capture = TIM_GetCapture2(TIM3);
TIM_SetCompare2(TIM3, capture + 21);
}
/* TIM3_CH3 toggling with frequency = 732.4 Hz */
if (TIM_GetITStatus(TIM3, TIM_IT_CC3) != RESET)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_CC3);
capture = TIM_GetCapture3(TIM3);
TIM_SetCompare3(TIM3, capture + 24);
}
/* TIM3_CH4 toggling with frequency = 1464.8 Hz */
if (TIM_GetITStatus(TIM3, TIM_IT_CC4) != RESET)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_CC4);
capture = TIM_GetCapture4(TIM3);
TIM_SetCompare4(TIM3, capture + 28);
}
