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How to pass a variable read in an interruption to main()

amelendez
Associate III
Posted on June 14, 2017 at 15:14

I'm reading a serial ADC from an interruption (24 bits)

I need to pass its read value to the main()

I have defined in /* USER CODE BEGIN PV */ a volatile variable uint32_t  xxxxx

The xxxxx variable is right inside the interruption routine but it becomes 0x01FFFFFE when called in main()

How can I pass the xxxxx variable from       void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)     to      main()?

12 REPLIES 12
Posted on June 14, 2017 at 15:18

A global variable should be visible in main()

You might want another flag to indicate the presence of new data if that can't be inferred from the data itself.

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Posted on June 14, 2017 at 16:27

I did as it follows

/* USER CODE BEGIN PV */

uint32_t show;

volatile uint32_t measure;

/* USER CODE END PV */

int main(void) {

   HAL_Init();

   SystemClock_Config();

   MX_GPIO_Init();

   while (1)   {

      show = measure;

   }

}

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)

{

   uint8_t i;

   if(GPIO_Pin== GPIO_PIN_3) {

      HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET);

      measure = 0;

      for (i=0; i<24;i++) {

         HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET);

         if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3)) {

               measure ++;

            }

      measure = measure*2;

      HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET);

      }

      HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET);

   } else{

         __NOP();

      }

   }

show and measure declared as global

measure is valid in the      void

 HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)    scope

but become  0x1FFFFFE in main () when show = measure

Thanks

Posted on June 14, 2017 at 16:55

Probably because you're causing PA3 to bang up and down in an interrupt that triggers on PA3?

Consider using a flag to indicate if it filled the variable, or queuing the measurements, so you can see if the routine has entered multiple times.

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Posted on June 14, 2017 at 17:17

I have added a new global variable variable iterac

uint8_t iterac;

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)

{

uint8_t i;

if(GPIO_Pin== GPIO_PIN_3) {

newData = 1;

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET);

measure

= 0;

for (i=0; i<24;i++)

{

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET);

if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3))

{

measure ++;

}

measure

=

measure

*2;

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET);

}

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET);

} else{

__NOP();

}

iterac = i;

}

debugging (breakpoint at iterac = i) I see that the callback always return when iteract = 24 (that is i=24)

and measure is 0x0100033E

after 24 pulses at PA6, PA3 has been 0x0100033E. That is, there have been edges at PA3 but the interruption has only executed once.

Posted on June 14, 2017 at 18:02

>>

I see that the callback always return when iteract = 24 (that is i=24)

Well no doubt, I'm suggesting that the interrupt is reentering, not preemptively.

Make iteract a 32-bit free running counter, ie don't reset it to zero at each interrupt entry, or to the loop count.

In your main loop printf() iteract and show/measure to the SWV console.

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Posted on June 14, 2017 at 18:08

Why the heck is everything being moderated today?

volatile uint32_t iterac = 0;

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)

{

uint8_t i;

iterac++; // Entry count

if(GPIO_Pin== GPIO_PIN_3) {

newData = 1;

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET);

measure

= 0;

for (i=0; i<24;i++)

{

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET);

if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_3))

{

measure ++;

}

measure

=

measure

*2;

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET);

}

HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET);

} else{

__NOP();

}

}

...

   while (1)   {

      if (measure != 0xFFFFFFFF)

     {

        show = measure;

        measure = 0xFFFFFFFF;

        printf('%08X %08X\n', iterac, show);

      }

   }

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Posted on June 14, 2017 at 18:21

iterac continously increasing

show and measure 0x01FFFFFE

Posted on June 14, 2017 at 18:59

And that's not what you see when you break-point the exit of the IRQ? Don't single step the clocking

Using what tools? Or what processor/board?

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Posted on June 15, 2017 at 08:42

I'm configuring the board by means STM32CubeMX

The processor is the STM32L100RC

The board is designed by me

I'm going to review the hardware. Perhaps a noise glitch in the EXTI/DataIN (PA3) is triggering the interrupt