CC2640R2F: How to reset the GPT timer value after timer stop when using the RTOS driver

Hi Sy,

thanks for your quick reply, however I think the timer is not reset by the SetLoadValue(SCB_Timer, 0) command. I have created a short program which demonstrates my problem by some Oscilloscope shots (see below).

In this program I have implemented two timers (Timer1 and Timer2) and I use a digital output Board_DIO1 which show the timer result and which I added the scope shots.

I initially start Timer1 and Timer2 at the same time, whereby Timer1 is loaded with a delay time of 8ms and Timer2 is loaded with a delay time of 5 ms. Both timers call an interrupt routine which creates a semaphore, the main program is waiting for this semaphore . After Timer2 has finished the 5ms delay the main program continues and stops the Timer1 which has not yet reached the match value. In the second step I want to create another 2ms delay with Timer1 (which was stopped before) and create another pulse of 2 ms . The desired result of the digital output is a pulse of 5ms closely followed by a 2ms delay and another 2 ms pulse. The Oscilloscope shot shows that there is a delay of roughly 350ms between the 1st and 2nd pulse which I only can explain that the timer value is not reset when loading the 2ms match value but still has the 5ms from the first run - as a matter of fact the timer completely counts up the 24 value which is 0xFFFFFF at 48MHz or 350ms and then reaches the match value of 2ms. I have also tried your proposal of setting a SetLoadValue(Timer1, 0) after the Timer_stop() but there was no different result.

Reading the technical reference I also understand that the timer value is only reset to the load value for the count down mode - I do not find any remark in technical reference that in count up mode the timer value is modified and I also did not find any special command in the driver source code which gives an indication of timer value modification.

My real program is a driver for a UART communication where I use Timer1 to read bytes out of the Uart FIFO, sample certain bits etc. (it is a quite extensive state machine). The Timer2 is in my application the interrupt of Uart frame errors in communication which need to trigger time critical synchronization.

Here is the code which I used to demonstrate and I attached the scope shots:

   GPTimerCC26XX_Params params1;

   GPTimerCC26XX_Params_init(&params1);

   params1.width          = GPT_CONFIG_16BIT;

   params1.mode           = GPT_MODE_ONESHOT_UP;

   params1.debugStallMode = GPTimerCC26XX_DEBUG_STALL_OFF;

   GPTimerCC26XX_Handle Timer1 = GPTimerCC26XX_open(CC2640R2_GPTIMER1A, &params1);

   GPTimerCC26XX_registerInterrupt(Timer1, SCB_TimerINT_SendSemaphoreAfterDelay, GPT_INT_TIMEOUT);

   GPTimerCC26XX_Params params2;

   GPTimerCC26XX_Params_init(&params2);

   params2.width          = GPT_CONFIG_16BIT;

   params2.mode           = GPT_MODE_ONESHOT_UP;

   params2.debugStallMode = GPTimerCC26XX_DEBUG_STALL_OFF;

   GPTimerCC26XX_Handle Timer2 = GPTimerCC26XX_open(CC2640R2_GPTIMER1B, &params2);

   GPTimerCC26XX_registerInterrupt(Timer2, SCB_TimerINT_SendSemaphoreAfterDelay, GPT_INT_TIMEOUT);

   Types_FreqHz  freq;

   BIOS_getCpuFreq(&freq);

   GPTimerCC26XX_Value LoadVal_per1msec = freq.lo / 1000;

   GPTimerCC26XX_Value DelayTime1 = 8 * LoadVal_per1msec - 1;

   GPTimerCC26XX_Value DelayTime2 = 5 * LoadVal_per1msec - 1;

   GPTimerCC26XX_setLoadValue(Timer1, DelayTime1);                // Timer1 setup to count up to 8ms

   GPTimerCC26XX_setLoadValue(Timer2, DelayTime2);                // Timer2 stops after 6ms and creates semaphore

   PIN_setOutputValue(&SYSPinState, Board_DIO1, 1);

   GPTimerCC26XX_start(Timer1);

   GPTimerCC26XX_start(Timer2);

   Semaphore_pend(Task_SCB_Semaphore, BIOS_WAIT_FOREVER);

   PIN_setOutputValue(&SYSPinState, Board_DIO1, 0);

   GPTimerCC26XX_stop(Timer1);

//    GPTimerCC26XX_setLoadValue(Timer1, 0);                       // here I inserted the SetLoadValue = 0 which had no effect

   DelayTime1 = 2 * LoadVal_per1msec;

   GPTimerCC26XX_setLoadValue(Timer1, DelayTime1);                // Timer1 setup to count up to 8ms

   GPTimerCC26XX_start(Timer1);

   Semaphore_pend(Task_SCB_Semaphore, BIOS_WAIT_FOREVER);

   PIN_setOutputValue(&SYSPinState, Board_DIO1, 1);

   GPTimerCC26XX_setLoadValue(Timer1, DelayTime1);                // Timer1 setup to count up to 8ms

   GPTimerCC26XX_start(Timer1);

   Semaphore_pend(Task_SCB_Semaphore, BIOS_WAIT_FOREVER);

   PIN_setOutputValue(&SYSPinState, Board_DIO1, 0);

   while (1) {;}

The first scpe shot shows the delay time of both pulses, the 2nd shot only shows the first pulse.

Hi Berthold, I am currently working on the oneshot up timer as well, same results. Have you been able to solve this issue?

Hi Dan,

I have implemented now a workaround which works in my case: After stopping the timer I read the free running timer value and add this to the new delay time. Not very smart, but I tested a few cases and it seems to work in my case.

The modification of the test code which I posted recently is as follows:

    GPTimerCC26XX_stop(Timer1);
    UInt32 CurrentCntVal = GPTimerCC26XX_getFreeRunValue(Timer1) & 0xFFFFFF;
    DelayTime1 = CurrentCntVal + 5 * LoadVal_per1msec;                 // delay time of 5ms
    GPTimerCC26XX_setLoadValue(Timer1, DelayTime1);               
    GPTimerCC26XX_start(Timer1);
    Semaphore_pend(Task_SCB_Semaphore, BIOS_WAIT_FOREVER);

Best regards

Berthold