• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 32 subscribers
  • Views 2316 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

PWM in TIVA

Mohamed Rahali
Intellectual 555 points


Hello all !!

I have a question about my TIVA board:

What is the range of frequencies that we can get for the PWM, taking into account the possibilities of "clock division" and the "number of bits"? I ask you if in case we had to measure a resonator with the PWM as a generator (at 50% duty cycle).

regards

  • 0
    Guru 117855 points

    Question alone signals that you're smart enough to "develop a method" to answer.

    Would you not:

    • Review MCU manual - PWM Section - noting the PWM architecture & clock sources
    • Good read of that PWM Section should reveal any "special and/or restrictive" demands which impact PWM frequency
    • Visit MCU manual's rear (where the detailed specs reside)
    • As a last (and best) resort - after the above review - you can follow: "Peripherals/Examples/PWM" for a code model, apply light load - and develop an EXACT Answer!

    As you have a "board at hand" - and there will not always be others (near/able) to help - such experimentation will prove much to your advantage...

    (as a "swag" - I'd expect that FMax may reach 1/2 of your system clock (surely 1/4 system clock) and FMin should drop to somewhat under AC Line Frequencies.  (50, 60Hz))

    Best PWM performance results from your use of a "PWM Generator."   You may generate PWM more simply - and quicker - by employing one of the MCU's Timers - set to PWM Mode.   (you trade capability for speed/ease via the Timer)

  • 0
    TI__Guru 72500 points
    I am confused. Are you asking about the resolution of a PWM signal that can be generated by the TM4C device, or the resolution with which the TM4C can measure the PWM generated by some other device? (Sorry, it may be just a language issue.) In both cases the minimum resolution is that of the system clock with can run up to 80MHz for the TM4C123 devices and up to 120MHz for the TM4C129x devices. The PWM output modules have 16-bit load and compare registers. The universal time modules can be 16 bit capture registers or combined to form a 32 bit capture register. They also have 8 bit or 16 bit prescalers.
  • 0 in reply to Bob Crosby
    Guru 117855 points
    I'd vote that, "PWM as a generator" (initial post) strongly suggests, "MCU's PWM Output" capability...