osTimer arguments not functional

[Richard Lowe]

Posted on September 15, 2017 at 14:38

When creating a RTOS timer in CMSIS the documentation is clear:

http://www.keil.com/pack/doc/CMSIS/RTOS/html/group__CMSIS__RTOS__TimerMgmt.html#gaedd312bfdca04e0b8162b666e09a1ae6

When it states for creating a timer is described as:

osTimerId osTimerCreate(const osTimerDef_t * timer_def, os_timer_type type, void *argument)
�?

The part that isn't working is the argument portion:

Here's an example:

#include 'cmsis_os.h'
 
DigitalOut LEDs[4] = {
 DigitalOut(LED1), DigitalOut(LED2), DigitalOut(LED3), DigitalOut(LED4)
};
 
void blink(void const *n) {
 LEDs[(int)n] = !LEDs[(int)n];
}
 
osTimerDef(blink_0, blink);
osTimerDef(blink_1, blink);
osTimerDef(blink_2, blink);
osTimerDef(blink_3, blink);
 
int main(void) {
 osTimerId timer_0 = osTimerCreate(osTimer(blink_0), osTimerPeriodic, (void *)0);
 osTimerId timer_1 = osTimerCreate(osTimer(blink_1), osTimerPeriodic, (void *)1);
 osTimerId timer_2 = osTimerCreate(osTimer(blink_2), osTimerPeriodic, (void *)2);
 osTimerId timer_3 = osTimerCreate(osTimer(blink_3), osTimerPeriodic, (void *)3);
 
 osTimerStart(timer_0, 2000);
 osTimerStart(timer_1, 1000);
 osTimerStart(timer_2, 500);
 osTimerStart(timer_3, 250);
 
 osDelay(osWaitForever);
}�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

If you try this, it won't work.

Problem is when you follow the code from CMSIS you notice the

void* argument

is treated as an identifier in FreeRTOS.

The

void* argument�?�?

is populated on the pvTimerID member of the xTIMERstruct in FreeRTOS.

/* The definition of the timers themselves. */
typedef struct tmrTimerControl
{
const char*pcTimerName;/*<< Text name. This is not used by the kernel, it is included simply to make debugging easier. */ /*lint !e971 Unqualified char types are allowed for strings and single characters only. */
ListItem_txTimerListItem;/*<< Standard linked list item as used by all kernel features for event management. */
TickType_txTimerPeriodInTicks;/*<< How quickly and often the timer expires. */
UBaseType_tuxAutoReload;/*<< Set to pdTRUE if the timer should be automatically restarted once expired. Set to pdFALSE if the timer is, in effect, a one-shot timer. */
void *pvTimerID;/*<< An ID to identify the timer. This allows the timer to be identified when the same callback is used for multiple timers. */
TimerCallbackFunction_tpxCallbackFunction;/*<< The function that will be called when the timer expires. */
#if( configUSE_TRACE_FACILITY == 1 )
UBaseType_tuxTimerNumber;/*<< An ID assigned by trace tools such as FreeRTOS+Trace */
#endif
#if( ( configSUPPORT_STATIC_ALLOCATION == 1 ) && ( configSUPPORT_DYNAMIC_ALLOCATION == 1 ) )
uint8_t ucStaticallyAllocated; /*<< Set to pdTRUE if the timer was created statically so no attempt is made to free the memory again if the timer is later deleted. */
#endif
} xTIMER;�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?�?

So the following code is what I've implemented:

/* USER CODE BEGIN RTOS_TIMERS */
 /* start timers, add new ones, ... */
 // Heartbeat
 osTimerDef(heartbeat, status_feedback);
 feedback_heartbeat = osTimerCreate(osTimer(heartbeat), osTimerOnce, (void*)0);
 // Approved
 osTimerDef(approved, status_feedback);
 feedback_approved = osTimerCreate(osTimer(approved), osTimerOnce, (void*)1);
 // Denied
 osTimerDef(denied, status_feedback);
 feedback_denied = osTimerCreate(osTimer(denied), osTimerOnce, (void*)2);
 /* USER CODE END RTOS_TIMERS */
�?�?�?�?�?�?�?�?�?�?�?�?

I should be able to use something like:

void status_feedback(void const* args)
{
 switch((int)args)
 {
 case 0:
 // Here
 break;
 }
}�?�?�?�?�?�?�?�?�?

But no.

When examiningthe args variable I discovered that it is the address of the timer object. So this works:

void status_feedback(void const* args)
{
 if( args == feedback_heartbeat )
 {
 //here
 }
}�?�?�?�?�?�?�?

Long story short. Arguments don't work when creating an osTimer. Or have I got it wrong?

#soft-timer #cmsis-rtos #virtual-timer #rtos

[Rostyslav S]

Posted on March 28, 2018 at 16:35

the same observation