CC2430 OSAL timer

Rui Zhang69778

Other Parts Discussed in Thread: CC2430, CC2530

I see the OSAL timer in Z stack 1.4.3-1.2.1 for CC2430 is the 8 bit timer. The timer tick for OSAL is 1ms. I also notice that there are two different timer update schemes: Interrupt enabled and poll enabled

1. poll enabled: poll in big loop of system tasks. Hal_ProcessPoll() function in OSAL_Start_system will call HalTimerTick() to set the callback function to update sys clock

2. Int enabled: in "HAL_ISR_FUNCTION" int vector, halProcessTimer4() will set the callback function to update sys clock

I think both way works, the first way is "fake" timer and it would delay the time for task process. the second should be more accurate but interrupt current task which could use timer as calibration.

I saw Z stack uses both in different version: depending on HAL_BOARD_INIT() is executed first(INT based) or InitBoard() is executed first(poll based) in ZMain.c

Is there anyone who can confirm my investigation is right or wrong. if it is right, which is the best way to configure timer?

thanks

Rui

over 14 years ago

0 xyzzy over 14 years ago

TI__Expert 5255 points

Your observations are correct. If you use non-interrupt, 1ms clock "ticks" could be missed if an OSAL task takes longer than 1ms to execute, causing the OSAL time to slip. In applications that do not require somewhat accurate timing, this method avoids the overhead of timer ISR processing. It's left up to the application developer to decide whether they need to use interrupts.

0 Rui Zhang69778 over 14 years ago in reply to xyzzy

Genius 4525 points

thanks for your reply. Just want to make sure this INT will be "missed" or "delayed". I saw the interrupt register flag only being cleared in halProcessTimer4(). So I think it will be "delayed". Also I saw some thread said OSAL timer is based on MAC 320us timer. Is that only for CC2530. Because in CC2430 Z stack 1.4.3-1.2.1, I saw it used 8 bit timer HWtimer 4. not the 16 bit timer. Just try to make sure which timer triggers the OSAL timer

Thanks

Rui

0 Dirty Harry over 14 years ago in reply to Rui Zhang69778

TI__Mastermind 19350 points

I think the either method has significant shortcomings such that you should throw them both away and just implement the OSAL clock from the sleep timer tick - you'll never lose time because that thing is always ticking - even in PM2!

/**************************************************************************************************
Filename:       osal_clk.c
Revised:        $Date: 2011-04-11 10:53:58 -0700 (Mon, 11 Apr 2011) $
Revision:       $Revision: 25649 $

Description: A replacement for OSAL Clock definition and manipulation functions.

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/* ------------------------------------------------------------------------------------------------
* Includes
* ------------------------------------------------------------------------------------------------
*/

#include "comdef.h"
#include "hal_z3d.h"
#include "OSAL_Clock.h"

/* ------------------------------------------------------------------------------------------------
*                                           Macros
* ------------------------------------------------------------------------------------------------
*/

#define TS_ST_GET(STCNT) st (    \
uint32 T32 = 0;                \
                                 \
do {                           \
    (STCNT) = T32;               \
    /* Get the sleep timer count; ST0 must be read first. */\
    ((uint8 *) &(T32))[0] = ST0; \
    ((uint8 *) &(T32))[1] = ST1; \
    ((uint8 *) &(T32))[2] = ST2; \
} while (T32 != (STCNT));      \
)

/* ------------------------------------------------------------------------------------------------
* Local Variables
* ------------------------------------------------------------------------------------------------
*/

static uint32 stLast;
static uint16 stRem;

/**************************************************************************************************
* @fn          osalTimeUpdate
*
* @brief       This function uses the free-running Sleep Timer ticks to update the 1-msec OSAL
*              timers.
*
* input parameters
*
* @param       None.
*
* output parameters
*
* None.
*
* @return      None.
**************************************************************************************************
*/

void osalTimeUpdate(void)
{
static uint8 run;

if (run == 0)
{
    run = 1;
    TS_ST_GET(stLast);
    return;
}

uint32 stCurr;
TS_ST_GET(stCurr); // Get the free-running count of 30.5 usec timer ticks.

if (stCurr != stLast)
{
    uint32 stTemp = stCurr;
    stCurr -= stLast; // Calculate the elapsed ticks of the free-running timer.
    ((uint8 *)&stCurr)[3] = 0; // Adjust for a carry on the 24-bit ST counter.
    stLast = stTemp;
    stCurr *= 125;
    stCurr += stRem;

uint16 msecs = (uint16)(stCurr / 4096UL);
stRem = (uint16)(stCurr - (4096UL * msecs));

    if (msecs)
    {
      osalTimerUpdate(msecs);
    }
}
}

0 Rui Zhang69778 over 14 years ago in reply to Dirty Harry

Genius 4525 points

Another question is about the energy consumption: Hal_ProcessPoll() will be executed in every for loop, and most time there will be no INT happen(32M sys clock compared with 1ms OSAL INT). so whether it is a huge energy waste to keep on poll timer INT?

Thanks

Rui

0 Rui Zhang69778 over 14 years ago in reply to Rui Zhang69778

Genius 4525 points

Thanks very much, dirty Hary. Just want to know whether it is possible that I can integrate this code into the Z stack 1.4.3-1.2.1 in CC2430, what other changes I need to do. what timer register the Sleep timer will use?

Also the Poll based timer will only be “delayed”, not “missed”, am I right? At the very beginning of OSAL_Start_System() process, there is Hal_ProcessPoll(),which calls the HalTimerTick(), which calls halProcessTimer4(). Based on DN116, the TIMIF register is set by Timer4 INT/OSAL every 1ms and the only way to clear it is to set T4CH0IF=0 in HalTimerTick(), the code will be like:

if (TIMIF & TIMIF_T4CH0IF)

{

T4CH0IF = 0; //DN116

halTimerSendCallBack (HAL_TIMER_2, HAL_TIMER_CHANNEL_A, HAL_TIMER_CH_MODE_OUTPUT_COMPARE);

}

For instance, if OSAL timer INT happens at 1ms, and my process will remain additional 2.5ms, this OSAL INT flag will be set as 1 for additional 2.5ms and be cleared at 3.5ms to 0, No timer miss will happen, am I right?

I saw there are two ways to trigger INT, overflow or output compare. CC2430 uses output compare mode but I can not find the T4CC0n in CC2430. Only “#define TCHN_T4CCL &(X_T4CC0)”, so what is the value for T4CC0n?

0 stones yang over 14 years ago in reply to Dirty Harry

Expert 1080 points

Hi,Dirty

I do not understand the programmer where

the stCurr *= 125;
stCurr += stRem;

uint16 msecs = (uint16)(stCurr / 4096UL);
stRem = (uint16)(stCurr - (4096UL * msecs));

    if (msecs)
    {
      osalTimerUpdate(msecs);
    }

why does stCurr multiply by 125?the stCurr *= 125;

And why is stCurr divided by 4086UL?uint16 msecs = (uint16)(stCurr / 4096UL);

Please tell me.Thanks in advance.

Regards,

stones

0 stones yang over 14 years ago in reply to Rui Zhang69778

Expert 1080 points

Hi,Rui

Could I have your QQ?I am also interested in the stack timer.I think using QQ is more convinient.

Regards,

stones

0 Rui Zhang69778 over 14 years ago in reply to Dirty Harry

Genius 4525 points

Hi, Dirty Hary, If I want to integrate this code to Z stack 1.4.3-1.2.1, Which dir I should put into?(OSAL?), also this one is also interrupt based, Am I correct? If so, what is the advantage of using this one instead of traditional INT based 32M clock. (I assume both introduce the INT handler overhead).

Thanks

Rui

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CC2430 OSAL timer