PWM Time shifting signal

[bmwael1]

Posted on January 09, 2013 at 17:20

Hi,

I program a

PW

M sig

nal in PB4 port using TIM3 using this program

int
main (
void
)
{
while
(1)
{
TIM3->CCR1 = 1000 ; 
}
}
/*____________________________TIM3______________________________*/
/* TIM3 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
/* GPIOB Clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4 | GPIO_Pin_5 | 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);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource4, GPIO_AF_TIM3);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource5, GPIO_AF_TIM3);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource0, GPIO_AF_TIM3);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource1, GPIO_AF_TIM3);
//________________________________________________________________
/*__________________________TIM3____________________________________*/
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 1999;
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);
//________________________________________________________________

It gives a PWM with

50% Duty Cycle

I want to shift time of this signal like this

I have already Signal 1 i want to create Signal 2 shifted by period T

Wh

at

parameter have

i to change ?

i try to change

TIM_TimeBaseStructure.TIM_ClockDivision = 0;

from 0 to 1 the signal change but i don't understand the

ClockDivision

effect

 What is the ClockDivision

interval variation to shift signal ? Thanks

Thank you

[bmwael1]

Posted on January 10, 2013 at 14:00

Any help ?

[John F.]

Posted on January 11, 2013 at 10:29

I don't have code suggestions ... but this looks like something you could do using the capture / compare feature. (From the Ref Manual...) ''When a match is found between the capture/compare register and the counter, the output compare function:

Assigns the corresponding output pin to a programmable value defined by the output compare mode (OCxM bits in the TIMx_CCMRx register) and the output polarity (CCxP bit in the TIMx_CCER register). The output pin can keep its level (OCXM=000), be set active (OCxM=001), be set inactive (OCxM=010) or can toggle (OCxM=011) on match.''

[Asantos]

Posted on January 15, 2013 at 14:18

I think you will need to use two different timers to do phase shifting. Use OC1 from the TIM1 to generate the signal 1, and  use the OC1 from the  TIM8 to generate the phase shifted signal 2, and use the  OC2 from the TIM 1 to clear the timer of TIM8. Controlling the OC2 timer you will control the phase shift between pwms.