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CCS/MSP430FR5969: timer triggering another timer

Ferran Reverter
Intellectual 645 points
Part Number: MSP430FR5969

Tool/software: Code Composer Studio

Dear colleagues,

I have a doubt about how peripherals can be triggered each other.

For instance, it is clear that a timer (after a given time interval, e.g. 1 second) can directly trigger the ADC to do the conversion without the intervention of the CPU.

However, it is not clear for me if a timer can trigger another timer, instead of the ADC. I mean, there is a timer running at low frequency at LPM3 and, for instance, each second it should directly trigger another timer (maybe running at high frequency at LPM1) to measure how long is a certain digital input signal. Is that possible? I would appreciate your feedback.

Best regards and thanks for your help!

Ferran

  • 0
    TI__Expert 5490 points
    Hello Ferran,

    There is no internal direct trigger for one timer to trigger another timer like you will do for ADC. However, to achieve what you are trying to do is possible and we see users do that sometimes.

    So let's assume:
    timer1 is running at low frequency at LPM3.
    timer2 is running at high frequency at LPM0.

    When the timer1 interrupt is triggered the system will go to active mode to process the instructions in your timer1 ISR.
    In thimer1 ISR you can start the timer2 and set the device to LPM0 and exit the ISR with LPM0.
    By doing this, you are using timer1 to trigger your timer2.

    Thanks,
    Yiding
  • 0
    Prodigy 190 points
    I'm a liitle confused. "Standard" timers Timer_A and Timer_B do not have LPM , they are running or not with respective configured source. One can run on low speed clock , other on high speed clock, with different power consumption.
    Probably You can use RTC for low power "seconds timer". But there is no direct triggering between RTC,Timer_A and Timer_B. You should do this in software. When RTC invokes its own ISR - there You can configure Timer_A or _B -
    some of their Capture/Compare block to capture on edge of measured signal. Additional work is needed in /capture/compare ISR.
    Your device has many other "non-classical" modules, i'm not sure about these.
  • 0
    Guru 95935 points
    It is possible to use a timer to trigger DMA (ref data sheet (SLAS704F) Table 6-12) to write a predetermined value into e.g. TA0CTL. This is a cute trick, but not particularly versatile (no decisions).

    I don't know of any way to switch LPM level (SR bits) autonomously using a timer.
  • 0
    Guru 26200 points

    Hello Ferran,

    timers are very tought.
    There is a range of TI products containing Timer Event Control (TEC) like MSP430x5xx and MSP430x6xx Family.
    Escaping from LPM modes, I hope you would find time signal combinations you are looking for.
    I hope TI sooner than later will bring something like Configurable Logic Cell provided by a competitor.

  • 0 in reply to Yiding Luo
    Intellectual 645 points
    Hi Yiding,
    Yes, you are right, but I wanted to avoid the current consumption required to attend the ISR in active mode. It seems, however, that this is no possible.
    Thanks for your feedback.
    Ferran
  • 0 in reply to Stefan Kanev
    Intellectual 645 points
    Thanks for the feedback, Stefan!
  • 0 in reply to Bruce McKenney
    Intellectual 645 points
    Thanks for the feedback, Bruce!

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