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Can I connect 5v analog to adc to tiva

ibrahem mostafa
Intellectual 510 points

Other Parts Discussed in Thread: TM4C123GH6PM

I used MPX sensor with tiva 
Mpx will give me adc signal from 0 to 5 v in tiva-c , and I need to work with it.
Any help :) ?
as Tiva adc is from 0 to 3.6 v  and Vref  of Tiva ADC is 3.5 volt !

and Can I changed the Vref which connected to ADC?

  • 0
    Guru 117855 points

    ibrahem mostafa said:
    Mpx will give me adc signal from 0 to 5 v in tiva-c , and I need to work with it.  Any help :) ?

    Once again this morning - "necessary info" but is it, "sufficient info?"   (universal issue here)

    Assumed is the "need" for your sensor to run from 5V.   And your read of sensor's data suggest that its analog output exceeds "VMax" of your MCU.

    That said - your Subject/Post Title speaks to a 5V ADC!   That does not seem the case - instead - should not that subject line be, 5V Analog Voltage?

    Cannot a simple 3V3/5V0 "Voltage Divider" accommodate (both) your sensor's output AND your MCU.   (very roughly you need a 40% reduction in signal level)   Now your sensor may not be able to drive a resistor network - low enough in value - to accommodate the MCU's ADC input specifications.   You may solve this by employing an op-amp as a "Voltage Follower" - and then dividing down it's output.

    Your final question - changing Vref  "connected to ADC" is unclear.   Which VRef - which ADC?

  • 0 in reply to cb1_mobile
    Intellectual 510 points

    I mean Voltage Reference ... page 808 in Tiva™ TM4C123GH6PM Microcontroller data sheet

  • 0 in reply to ibrahem mostafa
    Guru 117855 points

    Pardon but it is 05:30 (local, CST) & I'm not about to search for page 808 in an (unknown) data sheet. My friend - you must (better) realize that not all here (intimately) know of your project - and components - brevity is not your friend...

    There appeared substantial detail & guidance w/in 1st responding post - unclear what more (unthanked) I can do...

  • 0
    Guru 27665 points
    I think you'll find that the data sheet constrains both minimum and maximum values of Vref

    As cb1 suggests copy out the specifications section on Vref if you find it confusing. Then we can attempt to guide you.

    Robert