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ADS7957EVM-PDK: Signals not found on EVM-PDK.

Rick Jones78
Intellectual 340 points
Part Number: ADS7957EVM-PDK
Other Parts Discussed in Thread: ADCPRO, ADS7957

Am I getting real measured values, or something in a "canned" program?

I have the EVM-PDK running with results being displayed in ADCPro.  Results are impressively good.  So, I tried to verify inputs and outputs (analog and digital).  I connected a scope to pins on connectors P1 and P2.  But I can not find ANY signals (analog on P1, or digital on P2) while in the acquire mode.  I used the EVM-PDK's user's Guide (slau262d.pdf) schematic on p.27 (and some DVM probing to determine orientation).

ADS7957 is 1MSPs 12-bit 16 channel

Details of ADCPro setup:

EVM = Triple generator  sampling 44100 SPs; Ch 1=Sine, resolution = 16 (?), V=+15V, -15V (?) Codes= +32767 & -32768 (?), freq=10kHz, Amplitude= 0 dBFS.  I assumed CH0 or Ch1 would be stimulated.

Test - Multi FFT, 2048 samples, Block Size=16384.

Please help with how to find the signals.  Otherwise, I suspect the converter is not really being exercised in the 'EVM-PDK.

Thanks!

  • 0
    TI__Mastermind 25020 points
    Hello,
    The EVM paired with the MMB0 provide a simple interface and digital processing needed to comunicate with the device as well as provide power, it does not provide an input signal though. An input signal will still need to be provide to the device on the EVM. As you noted, P1 can be used to connect to the device inputs. The board provides Channel0 with the option to use an amplifier in the input drive circuit, through jumper W4. The rest of the channels only have on board provisions of an RC filter, so please be aware of the amplitude of the input signal being provided, signal should be unipolar up to VREF, or if selected, up to 2*VREF.
    The digital singla can be accessed through P2, when the device is converting, you should be able to see communiation to and from the device.
    Regards
    Cynthia
  • 0
    TI__Guru**** 180931 points
    Hi Rick,

    One additional note - the 'Triple Generator' is in fact a 'simulated' tool. You need to install and then load the ADS7957EVM plug-in for ADCPro.
  • 0 in reply to Tom Hendrick
    Intellectual 340 points

    Thanks to both of you, especially Tom for stating clearly and directly the triple generator is a simulation tool.  The documentation seemed subtle to me. 

    Please confirm: For external signals being applied, are there limitations due to the MMB0?

  • 0 in reply to Rick Jones78
    TI__Mastermind 25020 points
    Rick,
    The MMB0 does not restrict the input. Just be careful to stay within the operating conditions of the device