Systick time missing

[SRedd.5]

I am running the motor control workbench B-G431B-ESC1 board. The systick fires at every 2K frequency as per the user manual and the waveform matches when i toggle, but the problem is sometimes it misses as shown

I want to debug and find out why it misses those timings in between. Please suggest how do i find out? I am also running CAN in parallel at 500KBPS.

[Johi]

What is the effect of disabling CAN?

[SRedd.5]

Sorry for late response yes it is because of CAN task, how do i solve the problem? I will try to reduce the code in CAN ISR and put it in while(1).

[Johi]

No problem. Have you considered generating your waveform directly with a TIMER routed to GPIO or if the waveform is a bit more complex use DMA to drive GPIO and use a timer to drive the DMA timing? That way CAN ISR will not interfere with waveform generation. If needed I can provide an example code.

[Bob S]

DIsclaimer: I know nothing about the motor workbench code and run-time environment.

That said, if your "systick" is the normal ARM/STM32 systick timer, it typically defaults to the lowest interrupt priority.  You can change that and make it a higher priority (lower numeric value) than then CAN interrupts.  Presuming of course that the CAN interrupts can tolerate some delay when the systick interrupts them.  Or use a different timer (with a higher interrupt priority than the CAN interrupt) for that purpose.

Is the waveform you showed just "toggle a pin" inside the systick ISR to show when it is missed (or delayed), changing the priority may be all that is needed.  If that is indeed a waveform needed by your system, then changing to DMA/GPIO instead of code in an ISR as @Johi suggested might be needed.

[SRedd.5]

My main concern is SysTick_Handler is missing timing in between. The code is as below.

void SysTick_Handler(void)

{

#ifdef MC_HAL_IS_USED

static uint8_t SystickDividerCounter = SYSTICK_DIVIDER;

  /* USER CODE BEGIN SysTick_IRQn 0 */

 

  /* USER CODE END SysTick_IRQn 0 */

  if (SystickDividerCounter == SYSTICK_DIVIDER)

  {

    HAL_IncTick();

    HAL_SYSTICK_IRQHandler();

    SystickDividerCounter = 0;

  }

  SystickDividerCounter ++;

#endif /* MC_HAL_IS_USED */

 

  /* USER CODE BEGIN SysTick_IRQn 1 */

  /* USER CODE END SysTick_IRQn 1 */

    MC_RunMotorControlTasks();

CAN_Task();

HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_12);

 

   /* USER CODE BEGIN SysTick_IRQn 2 */

  /* USER CODE END SysTick_IRQn 2 */

}

How do i increase the priority of Systick interrupt? I am toggling the GPIO inside Systick handler.

[LCE]

Search your files for "HAL_NVIC_SetPriority(SysTick_IRQn;" (might be in STM32xxx_hal.c)

and set it to:

HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);

As BobS said: lower number, higher priority. So give some higher numbers to the other interrupts.

Check the description before the declaration of HAL_NVIC_SetPriority.

[SRedd.5]

When i searched this is what i found

HAL_NVIC_SetPriority(SysTick_IRQn, uwTickPrio, 0U);

#define __NVIC_PRIO_BITS 4U /*!< STM32G4XX uses 4 Bits for the Priority Levels */

uint32_t uwTickPrio = (1UL << __NVIC_PRIO_BITS); /* Invalid PRIO */

hence uwTickPrio  is 16, but as per the ST documentation

@PAram PreemptPriority: The pre-emption priority for the IRQn channel.
* This parameter can be a value between 0 and 15
* A lower priority value indicates a higher priority

The priority can be between 0 to 15 only.

 

 

[LCE]

Simply set both priorities to 0.

[SRedd.5]

It does not solve the problem still i get some missing times.

[SRedd.5]

Ok i will update the code.

[LCE]

What's happening if you turn of other interrupts, or at least do nothing (except setting a flag maybe) in the interrupt handlers?

[LCE]

BTW, the skipped pulse on the scope looks quite regular, maybe you show the interrupt handler where you toggle the GPIO.

And have you reduced the other interrupts' priorities?

[SRedd.5]

I have shown the code in my 2nd post. I have put the CAN interrupt lowest but unfortunately I am using the Systick as the base time for CAN as well do I need to use other timer. There is huge code in CAN and transmitting lot of messages around 9 with periodicity of 1 sec.

[LCE]

There's a lot happening in your SysTick_Handler, why that divider? 
That makes me assume that you are using a very high SysTick frequency, which again means that this interrupt handler is called too often. It should be good enough with 1 kHz for most applications.

And yes, try using another timer as base time for CAN.
You are using it for timeouts, message scheduling or what?

[SRedd.5]

Mainly for CAN message scheduling.

[LCE]

And again:
what's the time between the dropped pulses?
Maybe that might tell you something.