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cascading/combining ADCs on TM4c123g to make 24 Bit resolution

happyman
Prodigy 100 points

Hi 

I am new to micro controllers  . Just wanted to know if  anyone has ever attempted cascading /combining the two 12 bit ADCs present on TM4c123g Launchpad kit, to make a single 24 bit adc.

The idea is to use different values of Reference voltages  for the 2 ADCs as follows:

ADC 0 : VREFP= 0 v and VREFN = 1.5 v
and
ADC 1 : VREFP= 1.5 v and VREFN = 3.0 v

Using a Sample Sequence 3, and a simultaneous sampling for common input analog signal , perhaps can we achieve a 24 bit resolution.

thanks

  • 0
    TI__Guru**** 244380 points

    Hello Happyman

    The VREFP and VREFN are shared between the two ADC's and are not per ADC basis. So it would not be possible to do the step you have mentioned. Please note that the ADC's resolution is based on the number of steps it takes to convert the analog value to a digital one and not defined by the VREF range. The range of VREF will decide the min-max of the digital value for the converted range,

    Regards

    Amit

  • 0
    Guru 27285 points

    happyman said:
    I am new to micro controllers

    Ok

    happyman said:

    Using a Sample Sequence 3, and a simultaneous sampling for common input analog signal , perhaps can we achieve a 24 bit resolution.

     and also new to electronics conversion basics and electronic measurement...

     Splitting measure from half the reference you just add a bit in an insecure manner, so final resolution maybe NBIT + 1 +- uncertainity of middle reference, it can be of some help adding an external DAC driving VREF but is less expensive and better in precision use an external 24bit adc!!!

     So why settle so much just to add one bit and a lot of imprecision?

  • 0
    Prodigy 100 points

    Thank you very much for the really quick and precise responses.

  • 0 in reply to happyman
    Guru 117850 points

    Several of our young staff are curious - did your "quad copter" ever acheive controlled (and smiling) flight?

  • 0 in reply to cb1_mobile
    Guru 27285 points

    cb1_mobile said:

    Several of our young staff are curious - did your "quad copter" ever acheive controlled (and smiling) flight?

     Which quadcopter are you speaking about? I lost some interesting forum post?  Has someone ported flying code to TIVA?

  • 0 in reply to Roberto Romano
    Guru 47900 points

    Some short while back appeared poster, "Happy Smile."  And his "windmill" was quad copter - and "reach" far exceeded his "grasp."

    Arrives now (smile-less) poster - but still (self described) as Happy - and again, (it would seem) "pressing reality." 

    Laws of probability point to "match" - thus (way smart) young staff posed their question...

  • 0 in reply to cb1
    Guru 27285 points

    cb1- said:
    and "reach" far exceeded his "grasp."

     uhhh this one? GRASP

  • 0 in reply to Roberto Romano
    Guru 47900 points

    Roberto Romano said:
    uhhh this one?

    Not quite - try here: http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/p/362074/1272259.aspx#1272259

    As to the video you linked - we wonder if those were RF controlled or (each one) running pre-stored program.  Timing & coordination was critical - leads one to believe that each maneuver had been pre-programmed - and awaited an external Sync/Go signal.

  • 0 in reply to cb1
    Guru 27285 points

    cb1- said:
    Not quite - try here: http://e2e.ti.com/support/microcontrollers/tiva_arm/f/908/p/362074/1272259.aspx#1272259

     Seen, I was out of business that time ;)

    cb1- said:
    & coordination was critical - leads one to believe that each maneuver had been pre-programmed - and awaited an external Sync/Go signal.

     Autonomous flight and pattern+ image recognition. None can drive a similar trajectory nor can them be synced by manual action. All where preprogrammed to do a task from camera and sensor. On video some close view and camera vision from remote is available and as for sync none can see nothing in a fast moving camera nor can rf drive them in a so fast trajectory.

     Another fancy come from here far away from GRASP:

    ETH ZURICH

    and how it work

  • 0 in reply to Roberto Romano
    Guru 47900 points

    Roberto Romano said:
    None can drive a similar trajectory nor can them be synced by manual action. All where preprogrammed

    So - appears your expertise matches our (bit educated) guess.  We've (some) flight training - thus passing (over-flying) mountain seems more "real world" than passing thru hoop!

    As biz owner - I'd like to see inventory search/find/pick-up and other (helpful) activities - not so much, "star-wars."  (how can small firms benefit - if at all - from this?)  Seems important - yet unexplained.  (or hidden)

    We do thank you for finding/linking - as you know - having to make payroll - pay bills - drives one to "real applications!"