STM32F4 Free running 32-bit timer/counter

[Bill Lewis]

Posted on August 07, 2013 at 20:14

Can someone please point me in the right direction to use TIM2 or TIM5 as just a free running 32-bit counter, ticking at 1us, that I can read anywhere in my pgm.  No I/O or interrupts desired.

None of the examples in the software libs seem to do what I want.

Thanks, Bill

#simples #that-was-easy

[Tesla DeLorean]

Posted on August 07, 2013 at 20:19

Just configure the timebase and read TIMx->CNT

[Tesla DeLorean]

Posted on August 07, 2013 at 20:24

void TIM2_Configuration(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
/* TIM2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = ((SystemCoreClock / 1000000) / 2) - 1; // 1 MHz timebase, assumes APB1 @ SYS/4
TIM_TimeBaseStructure.TIM_Period = 0xFFFFFFFF; // Maximal
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
/* TIM2 enable counter */
TIM_Cmd(TIM2, ENABLE);
}

[Bill Lewis]

Posted on August 07, 2013 at 20:41

Thank you very much, Clive.

I was trying something like that, but the ''doc'' in the stm32f4xx_tim.h file included this:

/*!< Specifies the period value to be loaded into the active

        Auto-Reload Register at the next update event.

        This parameter must be a number between 0x0000 and 0xFFFF.  */

Taken at face value, 0xFFFF wasn't big enough for what I wanted to do.

[Tesla DeLorean]

Posted on August 08, 2013 at 00:22

I think I ran into that comment the other week, with the F3

STM32F3-Discovery_FW_V1.1.0\Libraries\STM32F30x_StdPeriph_Driver\inc\stm32f30x_tim.h

uint32_t TIM_Period; /*!< Specifies the period value to be loaded into the active
Auto-Reload Register at the next update event.
This parameter must be a number between 0x0000 and 0xFFFF. */
..
uint32_t TIM_Pulse; /*!< Specifies the pulse value to be loaded into the Capture Compare Register.
This parameter can be a number between 0x0000 and 0xFFFF */

Pretty much a hold-over from the F1 when all timers were 16-bit, now I have to check the manuals because I can never remember which parts have which timers. The F3 only has one.