Count the frequency of 3 external signals

[joneuhaus]

Posted on March 18, 2008 at 05:58

Count the frequency of 3 external signals

[joneuhaus]

Posted on May 17, 2011 at 12:26

Hello,

I would like to measure the frequency of 3 differents signal (max frequency = 100kHz).

What is the best way to handle this problem?

> Use the Timers 2,3 and 4 in Input Capture mode and check the value of the counter register each second

> Use an interruption to detect new pulse

> Use an external counter and retrieve its value each second (which one?)

> others ideas?

Have you some configuration example to use a Timer in Input Capture mode?

Thank you in advance for your advices.

[joneuhaus]

Posted on May 17, 2011 at 12:26

I have used an other way to measure frequency : I use a standard input and retrieve the value each second. Here is the code.

It works up to 450kHz, on 3 different inputs.

Here is the main code :

int main (void)

{

/* System Clocks Configuration */

RCC_Configuration();

/* NVIC configuration */

NVIC_Configuration();

/* Configure the GPIOs */

GPIO_Configuration();

/* Configure the USART1 */

USART_Configuration();

/* Clear reset flags */

RCC_ClearFlag();

/* private variables declaration */

bool bln_HF1,bln_F1,bln_E1;

bool bln_HF2,bln_F2,bln_E2;

bool bln_HF3,bln_F3,bln_E3;

unsigned int value=0;

int cpt1=0,cpt2=0;

/* Infinite loop */

while (1)

{

/* If 1s has passed */

if(TimeDisplay == 1)

{

/* Display counter values */

printf(''cpt1 : %d / cpt2 : %d/ cpt2 : %d\t'',cpt1,cpt2,cpt3);

cpt1=0;

}

/* Rising edge detection and incrementation of counter 1 (PC1) */

bln_E1=GPIO_ReadInputDataBit(GPIOC, GPIO_Pin_1);

bln_F1=~bln_HF1&bln_E1;

bln_HF1=bln_E1;

if (bln_F1) cpt1++;

/* Rising edge detection and incrementation of counter 2 (PB9) */

bln_E2=GPIO_ReadInputDataBit(GPIOB, GPIO_Pin_9);

bln_F2=~bln_HF2&bln_E2;

bln_HF2=bln_E2;

if (bln_F2) cpt2++;

/* Rising edge detection and incrementation of counter 2 (PA0) */

bln_E3=GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0);

bln_F3=~bln_HF3&bln_E3;

bln_HF3=bln_E3;

if (bln_F3) cpt3++;

}

}