Tachometer

[vinicius_acvasconcelos]

Posted on May 28, 2009 at 16:54

Tachometer

[vinicius_acvasconcelos]

Posted on May 17, 2011 at 13:12

I`m using the st code example ''PWM_Input''. It's working perfect, but the problem is the minimum frequency to measure is 1100Hz.

I wanna to measure frequency starts with 10Hz. How can I modified this example to measure 10Hz, thre is any prescaler to devide the 72Mhz? The code: TIM_ICInitStructure.TIM_Channel = TIM_Channel_2; TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; TIM_ICInitStructure.TIM_ICFilter = 0x0; TIM_PWMIConfig(TIM2, &TIM_ICInitStructure); /* Select the TIM2 Input Trigger: TI2FP2 */ TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2); /* Select the slave Mode: Reset Mode */ TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset); /* Enable the Master/Slave Mode */ TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable); /* TIM enable counter */ TIM_Cmd(TIM2, ENABLE); /* Enable the CC2 Interrupt Request */ TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE); void TIM2_IRQHandler(void) { /* Clear TIM2 Capture compare interrupt pending bit */ TIM_ClearITPendingBit(TIM2, TIM_IT_CC2); /* Get the Input Capture value */ IC2Value = TIM_GetCapture2(TIM2); if (IC2Value != 0) { /* Frequency computation */ velmotor = (72000000/ IC2Value); } else { velmotor= 0; } } Thanks.

[jaroslaw2]

Posted on May 17, 2011 at 13:12

Try this:

Code:

<BR>TIM2->PSC=(u16)iPrescalerForPWMI; <BR>

[ This message was edited by: jaroslaw.oska on 25-05-2009 14:38 ]

[vinicius_acvasconcelos]

Posted on May 17, 2011 at 13:12

The PSC is used select the numbers of envents to capture, I wanna only one envent(the period to measure the frequency).

Quote:

On 25-05-2009 at 14:36, Anonymous wrote: Try this:

Code:

<BR><BR>TIM2->PSC=(u16)iPrescalerForPWMI; <BR><BR>

[ This message was edited by: jaroslaw.oska on 25-05-2009 14:38 ] [ This message was edited by: vinicius_acvasconcelos on 25-05-2009 16:54 ]

[vinicius_acvasconcelos]

Posted on May 17, 2011 at 13:12

I solved the problem :-] using a function to devide the tim clock, for 655535. Now the frequency step is around 0.016Hz. I'm able to measure the 40 Hz.

TIM_PrescalerConfig(TIM2, 0x1987, TIM_PSCReloadMode_Immediate); TIM2_IRQHandler: /* Clear TIM2 Capture compare interrupt pending bit */ TIM_ClearITPendingBit(TIM2, TIM_IT_CC2); /* Get the Input Capture value */ IC2Value = TIM_GetCapture2(TIM2); velmotor = (11017.5975/ IC2Value);

[jaroslaw2]

Posted on May 17, 2011 at 13:12

Did you see function you've used?

void TIM_PrescalerConfig(TIM_TypeDef* TIMx, u16 Prescaler, u16 TIM_PSCReloadMode) { /* Check the parameters */ assert_param(IS_TIM_ALL_PERIPH(TIMx)); assert_param(IS_TIM_PRESCALER_RELOAD(TIM_PSCReloadMode)); /* Set the Prescaler value */ TIMx->PSC = Prescaler; /* Set or reset the UG Bit */ TIMx->EGR = TIM_PSCReloadMode; }

[vinicius_acvasconcelos]

Posted on May 17, 2011 at 13:12

Quote:

On 26-05-2009 at 07:06, Anonymous wrote: Did you see function you've used? void TIM_PrescalerConfig(TIM_TypeDef* TIMx, u16 Prescaler, u16 TIM_PSCReloadMode) { /* Check the parameters */ assert_param(IS_TIM_ALL_PERIPH(TIMx)); assert_param(IS_TIM_PRESCALER_RELOAD(TIM_PSCReloadMode)); /* Set the Prescaler value */ TIMx->PSC = Prescaler; /* Set or reset the UG Bit */ TIMx->EGR = TIM_PSCReloadMode; } You are write. I had mistake PSC for IC1PS. The correct is change the PSC and not the IC prescaler. Thanks