topic Using periodic timer in MQX in MQX Software Solutions

Using periodic timer in MQX

RichardR — Tue, 08 May 2012 22:37:04 GMT

I am trying to use the periodic timer in MQX to call back to a function that sets an event every 100ms. I use _timer_start_periodic_every(callbackfunction, NULL, TIMER_KERNEL_TIME_MODE, 100). It appears to work great for some indeterminate time frame. At some point, it appears to start running the MQX timer task nonstop, never allowing lower priority tasks that are ready to run to do anything.

Ultimately, I'll be setting the time interfval to 1 second, hence the name of the event bit. I have gone through and disable all other tasks except the Idle task so as to make sure there was no interference from them. Has anyone seen a similar issue? Am I doing something wrong in the setup?

Here is the code that sets up the timer, and handles it, as well as the call back function.

_timer_start_periodic_every(AnalysisPeriodicNotify, (pointer)NULL, TIMER_KERNEL_TIME_MODE, 100L);

   while (TRUE)
   {
      if (_lwevent_wait_ticks(&analysisEvent, ANALYSIS_ONE_SECOND_BIT, FALSE, 0) == MQX_OK)
      {
         wakeEvents = _lwevent_get_signalled();

         if ((wakeEvents & ANALYSIS_ONE_SECOND_BIT) != 0)
         {
            _lwevent_clear(&analysisEvent, ANALYSIS_ONE_SECOND_BIT);
            AnalysisPeriodicHandler();
         }
      }
   }
}

static void AnalysisPeriodicNotify( _timer_id timer_id, pointer dummyPtr, uint_32 seconds, uint_32 milliseconds )
{
   (void)dummyPtr;

   _lwevent_set(&analysisEvent, ANALYSIS_ONE_SECOND_BIT);
}

Thanks in advance,

RIchard

Re: Using periodic timer in MQX

RichardR — Tue, 08 May 2012 22:39:43 GMT

I left out the top of the man task that is being awakened every 100ms, here it is:

static LWEVENT_STRUCT analysisEvent;

void AnalysisTask( uint_32 parameter )
{
   uint_32 wakeEvents;

   result = _lwevent_create(&analysisEvent, 0);
   if (result != MQX_OK)
   {
   }

Re: Using periodic timer in MQX

MarkP_ — Wed, 09 May 2012 22:07:55 GMT

Hi,

Code seems to be OK.

At MQX3.7 timers were OK, haven't yet tested them at MQX3.8.

Have you tested the mode TIMER_ELAPSED_TIME_MODE?

Manual says:

"mode [IN] — Time to use when calculating the time to expire;

one of the following:

TIMER_ELAPSED_TIME_MODE (use _time_get_elapsed() or _time_get_elapsed_ticks(),

which are not affected by _time_set() or _time_set_ticks())

TIMER_KERNEL_TIME_MODE (use _time_get() or _time_get_ticks())"

~Mark

Re: Using periodic timer in MQX

RichardR — Thu, 10 May 2012 01:22:39 GMT

I'll give that a try and see if it makes any difference.

Re: Using periodic timer in MQX

RichardR — Thu, 10 May 2012 01:49:50 GMT

It behaves identically. After some indeterminate time frame, in this case it was about 9000 times through the 100ms loop, the MQX timer task just starts running continuously, not yielding to any other tasks.

Re: Using periodic timer in MQX

RichardR — Thu, 10 May 2012 03:31:11 GMT

Further testing, if I modify the code as below, but leave in the peridic timer setup, which now calls a function that does nothing but return, it still hangs.

_timer_start_periodic_every(AnalysisPeriodicNotify, (pointer)NULL, TIMER_ELAPSED_TIME_MODE, 100L);

   while (TRUE)
   {
      if (_lwevent_wait_ticks(&analysisEvent, eventBits, FALSE, 10) == MQX_OK)
      {

If I comment out the call to _timer_start_periodic_every(...), it runs without any issue.

No other task in the project uses any form of _timer_startxxxxx.

Re: Using periodic timer in MQX

RichardR — Thu, 10 May 2012 20:26:55 GMT

Ran it overnight without the _timer_start, no problems. It does not do what I need it to do timing wise, but I think I can conclusively say that the issue is with the MQX timer task. If it matters, K60 is the target processor.

Re: Using periodic timer in MQX

DavidS — Thu, 10 May 2012 20:41:31 GMT

Hi All,

I tested this back with MQX3.6 on ColdFire. Here is the code snippet:

_timer_id PollTmr;

TIME_STRUCT mqx_time; //DES system time structure variable

_time_get(&mqx_time); //DES get current system time

   PollTmr = _timer_start_periodic_at(
        PollTimerNotification, //DES notification function to call when timer expires.
        0,       //DES no data pointer used
        TIMER_ELAPSED_TIME_MODE, //DES elapse mode
        &mqx_time,     //DES start time
        (uint_32)5000);    //DES elapes time in ms (5000ms = 5s)

if(PollTmr)
printf("\n_timer_start_periodic_at ERROR\n");

I'll put it back on the to-do list but if you get it going sooner please let us know.

Hope this helps.

Regards,

David

Re: Using periodic timer in MQX

RichardR — Fri, 11 May 2012 01:30:10 GMT

It behaves identically using what you posted. I also added explicitly initializing the timer with a larger stack. IAR claims that only 15% of the timer task stack is being used, but it is still hanging, in this case after about 12000 periodic notifications.

Re: Using periodic timer in MQX

MarkP_ — Fri, 11 May 2012 13:00:28 GMT

I used lwtimers in MQX3.7, they worked OK.

Functions to use: _lwtimer_create_periodic_queue and _lwtimer_add_timer_to_queue.

~Mark

Re: Using periodic timer in MQX

MarkP_ — Sun, 13 May 2012 20:31:29 GMT

Tested in Kwikstik with attached file. Works OK, no halt problem.

Tasks has 'jam'-loops, simulating excessive CPU load.

~Mark

Re: Using periodic timer in MQX

RichardR — Mon, 14 May 2012 21:01:41 GMT

If I remove most of my other tasks, I can get it to run without issue. I am working on figuring out specifically which task(s) are causing the problem, although none of them use timers other than _time_delay(), and timeouts in system calls waiting on events and such. CPU usage is low, my Idle task runs just fine right up until the problem occurs, at which point the very high priority MQX Timer task runs continuously.

Re: Using periodic timer in MQX

RichardR — Tue, 15 May 2012 01:56:59 GMT

Right now it's looking like an issue with the USB virtual comm device tasks and the MQX timer. When I disable those tasks, leaving all other tasks running, the problem goes away. We are using the MQX USB device library, and basing our virtual comm handling on the example code supplied with MQX.

Re: Using periodic timer in MQX

RichardR — Tue, 15 May 2012 03:51:13 GMT

In particular, it appears to be an issue with the transmit task for the USB virtual com device.

Re: Using periodic timer in MQX

RichardR — Tue, 15 May 2012 20:07:33 GMT

It also appears that I don't have to actually be transmitting anything, just have the TX task created seems to cause the problem.

Re: Using periodic timer in MQX

RichardR — Tue, 15 May 2012 21:11:09 GMT

It appears that it is not even the TX task, just having the task that calls USB_CDC_Periodic_Task periodically is enough to cause the problem, even with the USB TX and RX tasks not running.

Re: Using periodic timer in MQX

RichardR — Tue, 15 May 2012 21:59:12 GMT

It appears that the issue only comes up when I have an active connection to the virtual com port. No data being sent or received, just an open connection.

Re: Using periodic timer in MQX

RichardR — Tue, 15 May 2012 22:02:44 GMT

So to summarize...

Using MQX periodic timer to generate an event on a periodic basis, with the USB_CDC_Periodic_Task call enning peridoically (using _time_delay between calls), and having an an open connection to the virtual com port with not data being transmitted or received is what appears to cause the MQX timer task to run continuously after a semi random period of time.

As far as I can tell, if I change any one of those conditions, the problem does not occur. If I use _time_delay instead of the MQX periodic timer, my timing is wrong, but the problem goes away. If I remove the task that calls USB_CDC_Periodic_Task, the problem goes away, or if I do not open a connection to the virtual com port, the problem goes away.

Re: Using periodic timer in MQX

DavidS — Wed, 16 May 2012 20:32:55 GMT

Hi Richard,

Are you using the TWRK60n512 hardware?

Which version of IAR? 6.10/6.20/6.30?

I believe thread said MQX3.7. Correct?

Any other info I'm not asking please pass along :smileywink:

Can you post the project? Or if need be we can take off line.

Regards,

David

Re: Using periodic timer in MQX

RichardR — Wed, 16 May 2012 21:15:33 GMT

I am using a board of our own design with the K60 processor.

IAR 6.30.

MQX 3.7.

I cannot post the project.

One more point of interest, changing the priority of the MQX timer task from the default 1 to 8 makes the problem go away.