This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TimerConfigure unconfigures other half - possible improvement

Guru 20660 points

Replies: 5

Views: 803

Hi everyone,

I've found a possible improvement for a Tivaware function that caused me a bit of a bother.

I made a little API that easily configures a wide timer to time capture. To avoid going through the process ever again and even avoid copy paste errors.
But I ran into a problem when I configured first TIMERA and then TIMERB (in WTIMER0). The problem was that the TIMERA configuration was gone! Just gone.
Finding the reason was not that hard. Just take a look at the relevant part of the source code:

    //
    // Set the configuration of the A and B timers and set the TxPWMIE bit.
    // Note that the B timer configuration is ignored by the hardware in 32-bit
    // modes.
    //
    if(NEW_TIMER_CONFIGURATION)
    {
        HWREG(ui32Base + TIMER_O_TAMR) = (((ui32Config & 0x000f0000) >> 4) |
                                          (ui32Config & 0xff) |
                                          TIMER_TAMR_TAPWMIE);
        HWREG(ui32Base + TIMER_O_TBMR) = (((ui32Config & 0x00f00000) >> 8) |
                                          ((ui32Config >> 8) & 0xff) |
                                          TIMER_TBMR_TBPWMIE);
    }
    else
    {
        HWREG(ui32Base + TIMER_O_TAMR) = ((ui32Config & 0xff) |
                                          TIMER_TAMR_TAPWMIE);
        HWREG(ui32Base + TIMER_O_TBMR) = (((ui32Config >> 8) & 0xff) |
                                          TIMER_TBMR_TBPWMIE);
    }

This is the configuration on the TimerA and TimerB. Note that I will speak only of the TM4C123 part of the code. The rest I cannot speak much since I didn't analyze it (only using the TM4C123 right now - I saw more stuff in the TM4C129 config so I didn't bother) but it seems to be the same.
Now the problem is that it changes both the timers configs every time!! So if you use a function call for TimerA and then for TImerB then you will have a bad time. 

Basically:
Calling TimerConfigure() to configure only TimerA or TimerB will unconfigure the other.

Workarounds:
1º option - Always configure the 2 timers at the same time if you can.
2º option - If you can't assure that you will configure the 2 at the same time the only option is editing the register. Ex: Create your own (pretty simple in this case) function:

void User_TimerConfigure(uint32_t _base, uint32_t _timer, uint32_t _config){
	//
	// Disable the timers.
	//
	HWREG(_base + TIMER_O_CTL) &= ~(TIMER_CTL_TAEN | TIMER_CTL_TBEN);

	//
	// Set the global timer configuration.
	//
	HWREG(_base + TIMER_O_CFG) = _config >> 24;

	/*
	 * Configure the timers 
	 * Allows to configure both at the time as well only 1
	 */
	if( (_timer & 0xff) == TIMER_A)
		HWREG(_base + TIMER_O_TAMR) = ((_config & 0xff) |
				TIMER_TAMR_TAPWMIE);
	if( (_timer & 0xff00) == TIMER_B)
		HWREG(_base + TIMER_O_TBMR) = (((_config >> 8) & 0xff) |
				TIMER_TBMR_TBPWMIE);
}

This is just what I think how the function should work.
Correct me if I am saying something wrong and/or if my problem was related to something else.





Luís Afonso

For more reply options press "Use rich formatting" on the bottom right.

I have a blog that i am making to help some colleagues with learning Tiva:  https://sites.google.com/site/luiselectronicprojects/home
I have here now example codes for the Tiva more organized: https://github.com/LuisAfonso95

5 Replies

  • Hello Luis,

    The second approach is more favored but it may mean deprecating the ROM function for the same. Thanks for pointing it out. One more bug to file and check in the main build

    Regards
    Amit

    Regards,

    Amit Ashara

  • In reply to Amit Ashara:

    Of course I understand the implications on the ROM function though I think at least there should be a note on the Tivaware guide under the function description/notes - IMO.
    Maybe something like a Tivaware Errata with workarounds, in similarity to a MCU errata.

    I would dare say that maybe a new function should be added and older TimerConfigure kept as legacy? (of course the new function would not be in the ROM for at least older parts). Don't know what would be better for the Tiva team but I would of course like this ironed out.


    The "bug" seems to set the timer mode (bit 0 and 1) to 0x00 . That's considered reserved according to the datasheet so this does not even give a valid config which can result in even more chaotic results that could be hard to debug, ain't I correct?


    Luís Afonso

    For more reply options press "Use rich formatting" on the bottom right.

    I have a blog that i am making to help some colleagues with learning Tiva:  https://sites.google.com/site/luiselectronicprojects/home
    I have here now example codes for the Tiva more organized: https://github.com/LuisAfonso95

  • In reply to Luis Afonso:

    Hi Luis,
    It may make sense for you to briefly summarize (and link to this thread) @ the "Tell T.I." thread - before it exceeds its "shelf life." (30+ days have now elapsed)

    We note the, "Poetic Unjustice" of the (alleged) Configure causing Unconfigure...   A+ for your building, "Headline Writer" skills.   (but not yet to 200+ "hits" per day (like another))

  • Nice catch Luis,

    Amit, do keep in mind the possibility of use of the preprocessor to deal with deprecation. One of the nice things about a ROM library with header files and calling stubs is that it is easy to add patches/replacements to either replace the ROM functions or prequalify the arguments/massage the returns.

    Robert
  • In reply to cb1_mobile:

    Added it to the "Tell T.I." thread - before it exceeds its "shelf life.".

    I do still have at least 200 page visualizations each day on my blog somehow XD I don't update it in a long time.
    I both don't have time and I want to think a bit more about how I want to add more stuff. I need to do some big organizing day there.


    Luís Afonso

    For more reply options press "Use rich formatting" on the bottom right.

    I have a blog that i am making to help some colleagues with learning Tiva:  https://sites.google.com/site/luiselectronicprojects/home
    I have here now example codes for the Tiva more organized: https://github.com/LuisAfonso95

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.