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DAC for TM4C123G

Tristan Hyde
Prodigy 10 points

Hello All,

I'm looking for some clarification on the datasheet for this processor. I need a Digital-to-Analog Converter and the datasheet mentions a DAC in the ADC section. It mentions that it is capable of providing a 12-bit DAC operation. This however is basically the only mention of the DAC. Nothing on how to use it. Is there a DAC on chip or will i need to acquire another chip to handle my DAC operations?

Thank you

-Tristan 

  • 0
    Guru 20670 points
    Hi Tristan,

    There isn't any TM4C with DAC as far as I know and I am sure that part does not have a DAC since it never refers to it in a bigger extent
  • 0
    Guru 47900 points
    I agree w/poster Luis - no DAC appears w/in TM4C123.

    While I doubt it can reach to 12 bits - it is possible to produce DAC-like response via any of the MCU's Timers - configured into PWM mode - and then R-C filtering that signal. The weakness of this method is the slowed response time (as you must charge & discharge the external C) and the potential "aging" and temperature sensitivity of the 2 external components.

    If you really require 12 bits (which may prove a "reach") multiple vendors produce external DACs which may be controlled via I2C or SPI.
  • 0
    TI__Guru**** 244440 points
    Hello Tristan,

    Thank you for noting the same. I agree that it is a typo in the ADC section where it has been incorrectly mentioned a 12-bit DAC

    Regards
    Amit
  • 0 in reply to cb1
    TI__Guru**** 244440 points
    Hello cb1,

    Actually it does "The successive approximation uses a switched capacitor array to perform the dual functions of sampling and holding
    the signal as well as providing the 12-bit DAC operation."

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 47900 points

    Hi Amit,

    Amit Ashara said:
    Hello cb1,

    Actually it does "The successive approximation uses a switched capacitor array to perform the dual functions of sampling and holding
    the signal as well as providing the 12-bit DAC operation."

    I think you've "reached" a bit on this one, Amit.   The DAC you reference cannot be exposed to the outside world - can it?   While it does (technically) exist - it is FAR from serving any "normal/customary" DAC function.

    And that outside world exposure - clearly - is the poster's intent.    (i.e. he seeks to generate and output analog voltages - which I (still) see as beyond the TM4C123 class MCU.)   Further - that brief, unclear "mention" of the "confined DAC" w/in TM4C appears (here) to have caused more trouble than its worth!

    And (actually) - multiple (other vendor) ARM M4 MCUs provide that DAC function.   (and even cost-down M0 devices provide (real) DACs...)

  • 0 in reply to cb1
    TI__Guru**** 244440 points
    Hello cb1

    I believe you may have misread my first post on this topic. I do mention that it is a typo.

    Regards
    Amit
  • 0 in reply to Amit Ashara
    Guru 117855 points

    Hi Amit,

    Amit Ashara said:
    I believe you may have misread my first post on this topic.

    No - as my earlier quotation from you revealed - my last post was in counter to your writing, "Actually it does."

    Unclear is your meaning of "it" in that writing - and as both Luis & I did not believe any "real/usable" DAC had "found a home" w/in TM4C - it appeared that you were countering our (No usable DAC) belief.   Does that clarify?   And really - no usable DAC resides w/in TM4C.

    It is that "actuality" which generated my post...