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TMS570LC4357: wrong values from AD converter

Steven Wahlberg
Prodigy 90 points
Part Number: TMS570LC4357
Other Parts Discussed in Thread: HALCOGEN

Dear TI Community,

I'm new here and have a question please.

I want to capture the data from four microphones, each microphone is connected to an amplifier, and each output of the amplifier is connected to a channel in AD converter. In HALCoGen I configured the Pins 0 - 7- 19 - 20 for ADC 1 Group 1, 12 Bit.

I don’t configured Vccad, Vssad, Vrefhi and Vreflo. I have connected the ground of the microcontroller “TMS570LC4357ZWTQQ1” with the ground of my circuit.

 The Microcontroller is connected with my laptop via USB cable and I read the data via SCI.

 My problem is, I get wrong values of AD converter. There is no sound and it shows higher values. Please see screenshot

 Can you please check in my code whether it is right?

Or I have still something to connect to the microcontroller? For example Voltage Ground etc.

 Thank you for your response.

 best regards

 Jo.8032.screenshot.zip

  • 0
    TI__Guru 72500 points
    Did you measure the voltage at the ADC inputs with an oscilloscope? First determine if you have proper voltages at the input (0V to 3.3V).
  • 0 in reply to Bob Crosby
    Genius 3315 points

    Hi guys,

    just a remark regarding the input voltage range - of course, that depends on an external reference voltage value. As mentioned in datasheet SPNS195C, there are two options of the operating ranges:

    • Operating Characteristics Over 3.0 V to 3.6 V Operating Condition
    • Operating Characteristics Over 3.6 V to 5.25 V Operating Condition

    Cheers, Jiri