Hard fault running timer in one pulse mode

Posted on July 06, 2015 at 20:17

I am working with STM32F427ZIT6 (Keil MDK-ARM 5.15) and want to implement a delay function based on Timer 6 in a single pulse mode. The delay function is:

void Delay_us(uint16_t amt_us)
{
TIM6->CNT = 0;
TIM6->ARR = amt_us;
/* start timer and monitor update flag */
TIM6->CR1 |= 0x0001;
while ((TIM6->SR & 0x0001) == 0) {;}
TIM6->SR &= 0xFFFE; /* clear update flag */
/* timer stops */
} /* end Delay_us() */

Timer 6 initialization code is exported from STM32CubeMX:

/* TIM6 init function */
void MX_TIM6_Init(void)
{
TIM_MasterConfigTypeDef sMasterConfig;
htim6.Instance = TIM6;
//HAL_TIM_Base_Init(&htim6);
htim6.Init.Prescaler = 83; //168;
htim6.Init.CounterMode = TIM_COUNTERMODE_UP;
htim6.Init.Period = 0;
HAL_TIM_Base_Init(&htim6);
HAL_TIM_OnePulse_Init(&htim6, TIM_OPMODE_SINGLE);
// sMasterConfig.MasterOutputTrigger = TIM_TRGO_ENABLE;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
HAL_TIMEx_MasterConfigSynchronization(&htim6, &sMasterConfig);
}

sMasterConfig.MasterOutputTrigger = TIM_TRGO_ENABLE; is commented out since I don't need a trigger output. I also tried to use the ''old way'' initialization I always used with M3:

void TIM6_Init(void)
{
__TIM6_CLK_ENABLE();
/* prescaler register is loaded with value for Fcnt = 1 MHz at 84 MHz */
TIM6->PSC = 83;
/* timer is used as upcounter (DIR=0) in one-pulse mode (OPM=1), */
/* only overflow generates an update event (URS=1), */
/* update event is generated, no interrupt */
TIM6->CR1 = 0x000C;
} 

The only thing I have in a main loop is toggling of an output pin with a delay:

while (1)
{
/* toggle PB12 (TEST1) at 10 ms */
Delay_us(10000);
cnt++;
GPIOB->ODR ^= 0x1000;
}

Variable cntshows how many times the loop was executed. When I debug the program, it goes into Hard Fault after executing a loop a few times (I saw cnt equal to 1, 2, 81 etc. - no certain value. If I replace the call to the Delay_us() by the simple delay loop (delay value is not important)

for (uint32_t i = 0; i < 1000000; i++) {;}

no Hard Fault exception is generated. What can cause such behavior? I used this method many times with multiple M3s and never had any problems. Thank you for advice, Gennady