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TM4C129ENCPDT: Vref & Vdda pin connection

Nishitha Chandrasekar
Intellectual 700 points
Part Number: TM4C129ENCPDT


Hi Charles sir

I have a doubt in my circuit not required the Vdda & Vref pin what should i do???

  • 0
    Intellectual 700 points
    Hi Sir

    If Vdda & Vref pin is unused pin for my circuit, how to terminate it???
  • 0 in reply to Nishitha Chandrasekar
    Intellectual 700 points
    And also how to reuse that pins in future

    kindly guide me
  • 0 in reply to Nishitha Chandrasekar
    TI__Guru**** 191906 points
    If you don't plan to use the ADC at all then you can ground the VDDA and VREF.
  • 0 in reply to Charles Tsai
    Intellectual 700 points

    If i want to use this pin future means. what could i do???

  • 0 in reply to Nishitha Chandrasekar
    TI__Guru**** 191906 points
    Note that AINx signals are multiplexed with other functional signals. For example, AIN0 is multiplexed with PE3 and U1DTR. If you don't want to use AIN0 you can still configure the pin as a GPIO pin or as a UART functionality. If you plan to use the ADC in the future then you need to provide supply to VDDA and VREF.
  • 0 in reply to Charles Tsai
    Guru 117855 points

    Hi Charles,

    Along w/the ADC's use of VDDA & VREF - should not use of the 'Analog Comparator' - also benefit (possibly require) proper power connection to VDDA & VREF?

    For poster's general use (especially re-use, later) providing the proper 'Power Connections to VDDA/VREF' seems highly preferable... (as it enables the use of (both) ADC & Analog Comparators - and 'any other' MCU element - requiring such power inputs...

    Further - posters (and users) have been known (albeit upon (very) rare occasions) ... to CHANGE THEIR MINDS!     And then - if VDDA & VREF are 'Locked hard to GND' - it will prove difficult & time consuming - to employ (even) a single ADC channel.    And really - 'Ugly up poster's board!'

    Unless poster seeks to, 'Squeeze Away EVERY DROP of MCU Power Consumption' - providing proper (powered) connections to VDDA & VREF seems (almost) SOP!

  • 0 in reply to cb1_mobile
    TI__Guru**** 191906 points
    Hi cb1,
    Thanks. Your concern is very valid. The analog comparator needs the VDDA/VREF to provide the internal voltage reference. If the poster is or will be using Analog Comparator then the VDDA/VREF must be provided.

    I agree to never say never. :-) But it is poster's decision to make if he will be adding ADC functionalities in the future. The board nevertheless needs to be redesigned even if VDDA/VREF is provided today but the AINs are not routed in the board.
  • 0 in reply to Charles Tsai
    Guru 117855 points

    Hello and thank you, friend Charles,

    A "Heightening of such Board's 'Re-Use' rises - if (some) of the (potential) ADC pins are routed to (reasonable) pcb 'escape points' (vias) - such that future signals (either digital or analog) may (later) be introduced.     The 'flexibility' offered up by such method - has enabled our small firm to 'steal' Biz from far larger firms - as we were able to deliver prototypes (those past boards) far faster than if spinning 'anew!'

    Of ocurse it helps to have 'readied' an 'Analog plug-in board' - which 'mates' w/the main pcb.    

    Indeed the 'final' pcb may require 'customization' - yet the use of, 'Ready & Known/Proven Flexible' pcbs - serves to, 'Speed, Ease & Enhance' (both) the Development and SALES process.    (especially the SALES Process - where 'quickness/responsiveness' along w/ 'Proof of Concept' - so often proves key!)

  • 0 in reply to Nishitha Chandrasekar
    TI__Guru**** 191906 points
    Hi,
    Is your question answered and please do take the valuable suggestions from cb1? I will close the thread for now and you can reopen it or create a new post.
  • 0 in reply to Charles Tsai
    Guru 117855 points

    'Spies' - advise & inform - poster is (now) routing those (previously DEAD) ADC pins for, 'Change of Heart/mind' - Use/Access!   SO wise that!