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Hysteresis in TM4C123BE6PM

ISHAN SHAH1
Intellectual 370 points

Other Parts Discussed in Thread: TM4C123BE6PM

Hi,

Does the analog comparators in TM4C123BE6PM have hysteresis in them?? . If yes which registers needs to be programmed.

Thanks,

Regards,

Ishan

  • 0
    Guru 86785 points

    Hi,

        Doing a quick search of the word "hysteresis" at your device datasheet, there was a mention at ADC Digital Comparator Control Register. Explore further.

    -kel

  • 0
    Guru 117855 points

    ISHAN SHAH1 said:
    analog comparators in TM4C123BE6PM have hysteresis?

    Truth in advertising - don't have that MCU - have not pulled that specific data.  Instead - have earlier LX4F which has analog comparators (2) and offer this:  (you must determine fitness/degree of overlap - this suggestion vs. your MCU)

    Our device includes Register, "ACREFCTL."  This register enables user selection of 1 of 16 reference voltages - potentially supplied to the comparator's +ve input.  (MCU's notation)  Now these voltages may span ~2V (there are both "high" and "low" ranges) and the V"delta" (per step) is ~0.11V or ~0.15V (depends upon range) 

    Believe that normal/customary "intent" of this selection is the "setting" of comparator's "trip-point."  That said - by your "tweak" of that trip-point - just after the comparator's output transition - you may achieve a hysteresis effect.  (i.e. assume the comparator output has just toggled "high" - a quick write to ACREFCTL - reducing the reference voltage - may provide your desired hysteresis effect.  And - reverse (output toggling low) should also work via quick "increase" of that reference voltage.  (note - theory - I've not implemented... output may not remain stable nor glitch-free...)

    In our design - hysteresis is important - and we implement via "tried/true" series input R and Rfeedback across output & signal input.  (both Rs - external)  (We do not employ MCU's internal VRef as our design demands a variable setting - not fully met by the internal VRef ranging/step resolution.)   This external R method enables an "exact" hysteresis value.  Via additional HW - we may switch Rfeedback - and tailor the hysteresis - as/if required/useful...

    Our search, "hysteresis" (our MCU manual) reveals zero "hits" w/in Analog Comparator chapter.  (yet multiple w/in digital comparators & ADC section - but these are outside your specified Analog Comparator focus...)

    Again - you must "dig into" your MCU specifics.  As we're often told that rebrand is primarily "name change - and most parts (past -> present) are compatible" - method herein described may be appropriate - your MCU & objective...