Instable ticker on stm32f0308-DISCO

[joost-g]

Hi,

I ran into an issue using mbed's ticker on the stm32f0308-DISCO platform.
As can be seen from the scope images, the ticker callback is not called for a period, after which it is called multiple times. Issue occurs approximately twice every second.

Minimal working example to reproduce:

#include "mbed.h"

Ticker msTicker;
DigitalOut dev_led4(PC_8);

static void ticker_callback(){
    dev_led4=1;
    volatile int i;
    for(i=0; i<2500;i++);
    dev_led4=0;
}

int main(void){
    dev_led4 = 0;

    msTicker.attach(&ticker_callback, 0.01);
    while(1);
}

Normal/expected behavior

Non-uniform ticker callback

[0xc0170]

@bcostm @adustm

[JojoS62]

This problem looks like the same issue on the STM32F103 : #816
The code is the same for the F1 and the problem is the extension of the 16 bit counter/timer, it is not working as intended. Maybe a better solution is to concat two 16 bit timers, the ST timers have this option but I haven't tried it yet.

[bcostm]

Same issue as #816 on the 16-bit timer. The problem is understood and is under validation.

[Dieter-Graef]

I had a same issue on the STM32F746 Discovery board. The reason was that the ticker requires a free running counter to work. Therefor the autoupdate feature at reaching zero needs to be switched off. I added therefor the following line in the function HAL_InitTick:
TimMasterHandle.Instance = TIM_MST;
TimMasterHandle.Init.Period = 0xFFFFFFFF;

// TIMxCLK = PCLKx when the APB prescaler = 1 else TIMxCLK = 2 * PCLKx
if (RCC_ClkInitStruct.APB1CLKDivider == RCC_HCLK_DIV1)
  TimMasterHandle.Init.Prescaler = (uint16_t)((PclkFreq) / 1000000) - 1; // 1 us tick
else
  TimMasterHandle.Init.Prescaler = (uint16_t)((PclkFreq * 2) / 1000000) - 1; // 1 us tick

TimMasterHandle.Init.ClockDivision     = 0;
TimMasterHandle.Init.CounterMode       = TIM_COUNTERMODE_UP;
TimMasterHandle.Init.RepetitionCounter = 0;
HAL_TIM_OC_Init(&TimMasterHandle);
base[0].CR1|=TIM_CR1_UDIS;  //<- I added this
NVIC_SetVector(TIM_MST_IRQ, (uint32_t)timer_irq_handler);
NVIC_EnableIRQ(TIM_MST_IRQ);

[ciarmcom]

ARM Internal Ref: IOTMORF-196

[sg-]

@joost-g @bcostm is this resolved?

[LMESTM]

@sg- @joost-g @bcostm
There is a fix for this issue here - autoamtic tests are running now
anyone willing to do more tests is welcome
https://github.com/LMESTM/mbed/tree/STM32_16bits_tickers

[LMESTM]

ST_TO_BE_CLOSED
#4424 was merged - @joost-g the problem is fixed now, feel free to let us know if any further issue