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MCU-PLUS-SDK-AM273X: Can't get correct digital output from AD7389-4 ADC.

Lin Li
Intellectual 260 points

Part Number: MCU-PLUS-SDK-AM273X

Tool/software:

Hello Support Team,

I used AM273x EVM MSS_SPIB to control the AD's AD7389-4 ADC chipset. My SPI code can write to and from from AD7389-4's register very well.

However, I can't read back correct digital output when I supply a 10 KHz sine wave signal to analog channel 1.

On AM273x side I used 4-pin SPI Mode 2 (according to AD's support engineer suggestion). SPI clock is 2.5 MHz

On the AD7389-4 side, I used 1-wire mode and with normal average oversampling at ratio 16.

If needed I can share my SPI code here for reviewing.

Any advice and suggestion are greatly appreciated. We are blocked here for a while.

Looking forward to your response.

Best regards,

Lin

  • 0
    TI__Guru 57335 points

    Hi Lin,

    We cannot guarantee the AD's AD7389-4 ADC chipset to work. We can only guarantee the SPI read commands sent out to AD's AD7389-4 ADC chipset is correct. You prove it by using the Saleae capture. You should contact ADI for further support. You show them the Saleae capture of the whole set up procedure with ADI. They should be able to tell you why the AD7389-4 ADC chipset is not working as expected. 

    Best regards,

    Ming

  • 0 in reply to Ming Wei
    Intellectual 260 points

    Hi Ming,

    Thanks for your response. Sure I will keep consulting AD's support team.

    What's the highest SPI SCLK can we set in the example.syscfg file (currently I set it to 2.5 MHz), as we wonder if there is a under sampling issue?

    Best regards,

    Lin

  • 0 in reply to Lin Li
    TI__Guru 57335 points

    Hi Lin,

    According to the datasheet, the AM273x MIBSPI can support up to 25Mhz.

    Best regards,

    Ming

  • 0 in reply to Ming Wei
    Intellectual 260 points

    Hi Ming,

    When I increase the clock from 2.5 MHz to 20 MHz, I got the same issue.

    We may hit a data rate issue with the AD7389-4 chip set.

    As you know currently we set AM273x's MIBSPI as standard SPI and set AD7389-4 in 1-wire mode. To increase the data rate, can MIBSPI (not in standard SPI) support the 2-wire or 4-wire mode of the AD7389-4?

    Or if AM273x's QSPI can be used to support 4-wire mode of the AD7389-4? 

    Thanks for your help and support.

    Best regards,

    Lin

  • 0 in reply to Lin Li
    TI__Guru 57335 points

    Hi Lin,

    The MIBSPI does not support 2-wire or 4-wire mode.

    You can try QSPI

    Best regards,

    Ming

  • 0 in reply to Ming Wei
    Intellectual 260 points

    Hi Ming,

    Thanks for your information and continuous support.

    Best regards,

    Lin