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DAC8552EVM operation - can't run EVM

Nir Flysher
Expert 3287 points
Other Parts Discussed in Thread: DAC8552, DXP

Dear Team,

I have received an EVM of the DAC8552 for one of my customers.

We're trying to operate it without success.

Please see attached our steps.

We're working with the MMB0 board

1. Connecting the MMB0 + DAC8552 boards to power and USB and runing the DXP.

2. DXP can't download the DAC8552.xml automatically. From a short search on the web we've found the attached file and copied it to the following path : C:\Users\Public\Documents\DXP\Devices.

3. On the DXP software it shows green light. We press the 'Run DAC' button.

We expected to see a sinewave on the scope. Instead we just see some very low noise on the scope. When stopping the DAC the noise level on the scope reduces..

4. We've examined the inputs of the part and it seems like the SPI commands are going through correctly, the Vref is about 3.3V and the Jumpers are as described on the user guide.

Can you please advise ?

Best regards,

Nir.

DAC8552.xml 
<?xml version="1.0"?>
<device>
  <name>DAC8552</name>
  <revision>1.0.0</revision>
  <date>21Aug2012</date>
  <devicesettings>
    <instructionwidth>24</instructionwidth>
    <channels>2</channels>
    <format>sbinary</format>
    <dataword>CCCCXAXXDDDDDDDDDDDDDDDD</dataword>
    <commanddefault>3</commanddefault>
    <commandlatch>3</commandlatch>
    <maxupdaterate>1000000</maxupdaterate>
    <interface>
      <type>spi</type>
      <polarity>0</polarity>
      <phase>1</phase>
      <maxsclk>10000000</maxsclk>
      <framebits>24</framebits>
    </interface>
    <latchpin>
      <feature>0</feature>
      <pulsepol>0</pulsepol>
    </latchpin>
    <FSplus>5</FSplus>
    <FSminus>0</FSminus>
  </devicesettings>
</device>

  • 0
    TI__Genius 11750 points
    Howdy Nir,

    Can you take a picture of your setup, please include an image of the EVM with MMB0 (while active) and a screen capture of the GUI.

    Best Regards,
    Matt
  • 0 in reply to Matthew Sauceda
    TI__Mastermind 46290 points
    Nir,

    The MMB0 provides a 5V and 3.3V supply rail to the EVM board which is used to supply the DAC itself, however the reference and optional op-amp circuits are powered by a rail labeled "VCC" which is not generated by the MMB0. An external supply needs to be provided on the VCC net in order to use the on-board reference or amplifiers.

    Alternatively the on-board reference can be bypassed and and external reference can be provided at TP1.
  • 0 in reply to Matthew Sauceda
    TI__Expert 3287 points
    Hi Matt,
    Pictures or screenshots are not possible at this customer.
    Sorry, I know it makes it a bit more difficult.
    Best regards,
    Nir.
  • 0 in reply to Kevin Duke
    TI__Expert 3287 points
    Hi Kevin,
    Thanks.
    We supplied the external reference from power supply.
    As I mentioned above we've observed the Vref correctly on the DAC's pins.
    Do you think we should try and order a second EVM ?
    Best regards,
    Nir.
  • 0 in reply to Nir Flysher
    TI__Mastermind 46290 points

    Nir,

    Is the external reference being applied at TP1 with the jumper W4 set to the 2-3 position? Since it's not 100% clear to me yet exactly how the reference was measured "at the pins" I just want to make sure that everything is indeed in good shape.

    Similarly, I'd like to know exactly how the output is being measured as well. If you're not using the external op-amp circuit then W2 should be in the 1-2 position and the voltage output can be measured on pin 2 of the J4 header.