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DIAGNOSTICS MODE

Lokeswara Nath Bathala
Prodigy 80 points

Hi Praveen ,

In diagnostic mode the ledopen and led short bits diagnostic flag register depends on whether the sensor is connected to the probe..

Led open means the sensor is removed and the led short means sensor is connected?? is my analysis Is correct.

Regards,

Lokeswara nath B

  • 0
    TI__Mastermind 49956 points

    Hello Lokeswaranath,

    The diagnostic mode can be used to find out any fault with the sensor / sensor probe.
    As the Diagnostic register description in the datasheet points out any bit set in the DIAG register at the end of the Diagnostic sequence indicate a fault.

    LED open means the sensor is not connected to the AFE and LED short means that TXP and TXN are shorted.


  • 0 in reply to Praveen Aroul
    Prodigy 80 points
    hi aroul thanks for the reply

    I have a doubt on ambient cancellation current

    if u don't set the gain for ambient it takes default of 500kohms

    this gain is used to amplify the ambient value and cancel the ambient value with the cancellation current and after that if we use second stage gain that will amplify the ambient as well as the pleth component.


    now my doubt is whether u should amplification and cancellation of ambient value should be done on the fly .

    now I am using constant ambient gain.

    can u please explain the concept
  • 0 in reply to Lokeswara Nath Bathala
    TI__Mastermind 18285 points

    Lokeswara,

    Sorry for the delayed reply. What do you mean by "on the fly"?

    Do you mean as you are capturing the data from the ADC, you are using amplification and cancellation?

  • 0 in reply to Amy Schnoor
    Prodigy 80 points

    Amy,

    thanks for your reply 

    on the fly means real time when it is on the patients where it is dependent on different persons. Since the thickness of the finger differs and the gain required differs.

    before ADC in AFE , it has two gain stages with cancellation then the output of amplifier is going to ADC

    what I mean if you use second stage gain it amplifies ambient value, here I am trying to keep constant ambient value and constant second stage gain. whether it is correct or I need to change the gain  in real time.

    and in the cancellation current 1uA count (here count means 1uA =1000 then 10uA =10000). The count depends on the gains which u have . therefore we cannot cancel the ambient value completely.

    How to use the cancellation

    expecting a quick reply,

    thanks & regards

    Lokeswara

  • 0 in reply to Lokeswara Nath Bathala
    TI__Mastermind 18285 points
    Every subject will differ as far as the optimum settings. So, yes, you may need to change the gain in real time.

    Which AFE44xx are you using?