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TMS320F280023: Channel select of ADC A0 or C15 Configuration is affecting on the Other PINS of ADCA11/ADCC0 ,ADCA12/ADCC1 pins

Rakesh Bastawad
Prodigy 80 points
Part Number: TMS320F280023


Problem:

1. I have configured all the channels of ADCC and ADCA, then i have attached a pod to ADCA0/ADCC15 pin of ADC Channel for varying the ADC value and observing the value through debugger.

2. The value of ADCA0/ADCC15 is changing as we are varying the pod from 0 to 4096. while varying the pod, other pins are also changing the values but they are not connected to any external devices.

3. A11/C0 and A12/C1 Registers , which are changing the values.

Questions:

1. May i know why they are effecting while only pin (A0/C15) is connected to pod..?  what could be the Reason for it?

  • 0
    TI__Genius 11071 points

    Hello Sanmati,

    In general, you should not expect defined behavior from the ADC conversion if a pin or pins are left floating or disconnected. These particular pins have reserved internal functions inside the analog interconnect, and the isolation circuits probably got influenced by your bias voltage on A0. As long as a signal is driven on these pins following our ADC input driver design guidelines, they will function normally and within specification.

    Best regards,
    Ibukun