Posted on September 30, 2013 at 13:14
hello all and thanks for your help,
I'm working with stm32f4 discovery board and I will like to use two different timers. For the timer TIM3 after a long work I set certain parameters so I can have my desired behavior (generate a periodic signal with a properly dutycycle and frequence ). Because I saw on the datasheet that TIM2, TIM3, TIM4 and TIM5 have the same characteristic I though that the same settings that I used for TIM3 will work also for TIM4 for example but unfortunately is not.
Probably I miss something, I would like to understand the reason of this.
Here in the bottom is the simple code that I used.
#include ''stm32f4xx_gpio.h''
#include ''stm32f4xx_rcc.h''
#include ''stm32f4xx_tim.h''
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
void TIM_Config(void);
void PWM_Config(int period);
int main(void)
{
/* TIM Configuration */
TIM_Config();
/* PWM Configuration */
PWM_Config(800);
TIM3->CCR1=100;
TIM3->CCR2=100;
TIM3->CCR3=100;
TIM3->CCR4=100;
while (1)
{
}
}
void TIM_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* TIM3 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
/* GPIOC and GPIOB clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC | RCC_AHB1Periph_GPIOB, ENABLE);
/* GPIOC Configuration: TIM3 CH1 (PC6) and TIM3 CH2 (PC7) */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7 ;
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(GPIOC, &GPIO_InitStructure);
/* GPIOB Configuration: TIM3 CH3 (PB0) and TIM3 CH4 (PB1) */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
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(GPIOB, &GPIO_InitStructure);
/* Connect TIM3 pins to AF2 */
GPIO_PinAFConfig(GPIOC, GPIO_PinSource6, GPIO_AF_TIM3);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource7, GPIO_AF_TIM3);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource0, GPIO_AF_TIM3);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource1, GPIO_AF_TIM3);
}
void PWM_Config(int period)
{
uint16_t PrescalerValue = 0;
/* Compute the prescaler value */
PrescalerValue = (uint16_t) ((SystemCoreClock /2) / 28000000) - 1;
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = period;
TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
/* PWM1 Mode configuration: Channel1 */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 0;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
/* PWM1 Mode configuration: Channel2 */
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 0;
TIM_OC2Init(TIM3, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
/* PWM1 Mode configuration: Channel3 */
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 0;
TIM_OC3Init(TIM3, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);
/* PWM1 Mode configuration: Channel4 */
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = 0;
TIM_OC4Init(TIM3, &TIM_OCInitStructure);
TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_ARRPreloadConfig(TIM3, ENABLE);
/* TIM3 enable counter */
TIM_Cmd(TIM3, ENABLE);
}
Thank you for your help.
Pablo
#tim3-stm32f4-discovery
