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ADS8344: Converter always return 0xFFFF

Anna Vianelli
Prodigy 10 points
Part Number: ADS8344

Hello, I'm working with ADS8344 to convert analog data coming from a sensor.

ADC is connected to a uC and communication goes through SPI interface (2MHz clock). ADS8344 is set up in external clock mode, and in single ended channel mode. Power supply is given from uC and Vref is connected to Vcc (for now).

I see on the scope the busy signal as it shoud be (violet line), but regardless from the input, ADS8344 always return 0xFFFF (yellow line).

Any suggestions?

  • 0
    TI__Mastermind 24940 points

    Hello, 

    From the scope shot, the CS and SDI lines are not shown, would you please share the state of these as well. 

    The first suspect would be the voltage reference, please measure the voltage at the VREF pin to confirm there is no dip in voltage level. If the reference voltage level dips, this would result in higher than expected measurements. 

    Also recommend confirming the analog input voltage level as well. 

    regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 10 points

    blue line is CS, green line is SDI, pink/violet is busy and yellow is SDO.

    I don't see any dip in Vref, which is connected to Vcc (3.3 V). Analog input on CH0 is coming from a potentiometer, so for now it's set to be about 2.1 V. Pin 9 COM is grounded. Control byte is B10000111.

    Seems everything ok to me...

  • +1 in reply to Anna Vianelli
    Prodigy 10 points

    Sorry, figured out. Was a soldering issue of Vref pin.

    Thanks for support