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ADS5294: word_Wise mode and Global_EN_Filter initialization failure

Part Number: ADS5294

Hello Team,

My customer has some problems with the ADS5294.


1. The register 28 shows which output format is provided on the LVDS interface.

  •  In Word-Wise mode, something seems not to be set correctly in the module, since in this mode individual channels produce data errors for individual ICs (but not for a test ramp). Did this error occur in Word-Wise mode? We have been using the BIT-Wise mode since then
  •  According to the documentation and the table in the appendix, the BIT-Wise mode should be set at the highest D15 = 0 and D7 = 1. This can not be entered at all. Only D15 = 1 and D7 = 1 are possible. The output data then looks as if it were the BIT-Wise mode. Is our assumption correct here?

2. In register 29, the flag for GLOBAL_FILTER_EN and EN_CHANNEL_AVG can be set.
Here I can not set the bit for GLOBAL_FILTER_EN (as well as for the Averaging). Although the BIT GLOBAL_FILTER_EN is not set, ie 0, the high-pass filter appears to be switched on. Is the low-pass decimation filter connected? Why is it not possible to set the GLOBAL_FILTER_EN bit?

Thank you. Looking forward to hear from you.

Best,

Needhu

  • Needhu,

    I'm moving this thread since it is technically apart of the Medical group.
  • Amy,

    Thank you. I am looking forward for the support.

    Thanks,
    Needhu
  • Hi Needhu,

    The datasheet actually lists bit 8 in register 28 to set BIT_WISE mode. Can you please verify that with the customer?

    Also, is your customer using the ADS5294EVM GUi to configure the device in addition to the TSW1400 or a custom board setup?

    I'll respond to your other questions before the end of the week.

    Sincerely,

    Olu

  • Olu,

    Yes, I have done that. I am looking forward for your suggestions.

    Thank you.
    Needhu
  • Hi Olu,

    Please find additional information about the Faults.

    1. When I try to send the command 0x80FF via SPI to Register 28 the Modus is Word-Wise.

    When I try to send the command 0x0100 to Register 28 the Modus should be Bit-Wise, but it isn’t.

    When I try to read out the register 28 after writing 0x0100 I read back 0x000.

    So it is not possible to write 0x80FF into it.

    But when I write 0x8100 into it the Bit-Wise mode seems to be activated (because we see the data on the LVDS line in the expected way).

    The datasheet says that 0x0100 and not 0x8100 should be the Bit-Wise Mode. Can you also reproduce this fault?

    2. When we use the Word-Wise Modus Reg28=0x80FF and activate the Ramp all received data seems to be OK.

    But when we switch to the normal Input-Data we see failures at some channels (not always the same between different AD-Converter ICs).

    This failure is that at certain ADC-values (for example around 30) every second bit seems to corrupted. We can show that it could not be the FPGA implementation. So the question is, if there might be a problem with the sorting of the data within the ADS5294 when using the Word-Wise Modus.

    Thank you.

    Best,

    Needhu

  • Hi Needhu,

    I am looking into register 28's configurations for word-wise and bit-wise mode but in the meantime is there any way your customer can use byte-wise mode?
    The EVM is configured for byte-wise mode by default and there have been absolutely no issues with using that mode.

    I am also able to display output of ADC channel 3 on bin 2 (channel 2) by writing 0x0001 to register 0x29 and 0x0010 to register 0x2C. What exact features of the averaging function are you having trouble with?

    Sincerely,
    Olu
  • Hi Needhu,

    Thanks for helping the customer who is using our ADS5294 devices.

    We have also checked the following three registers in our lab.

    The following register settings are verified and they are working.

    If set Byte-wise mode, please set the register Address=0x28, Data=0x0000

    If set Bit-wise mode, please set the register Address=0x28, Data=0x8100

    If set Word-wise mode, please set the register Address=0x28, Data=0x80FF

    We will modify the ADS5294 datasheet very soon.

    Thank you very much for helping the customer.

    Best regards,

    Chen

  • Chen,

    Thank you very much. I will confirm if this works with the customer and get back to you.

    Thanks,
    Needhu
  • Hi team,

    Thank you, the first part of the question is solved.

    Do you have an answer for the second part of the question?

    2. In register 29, the flag for GLOBAL_FILTER_EN and EN_CHANNEL_AVG can be set.

    Here I can not set the bit for GLOBAL_FILTER_EN (as well as for the Averaging). Although the BIT GLOBAL_FILTER_EN is not set, ie 0, the high-pass filter appears to be switched on. Is the low-pass decimation filter connected? Why is it not possible to set the GLOBAL_FILTER_EN bit?

    Thank you.

     

    -Needhu

  • Hi Needhu,

    How are you?

    Thanks for helping the customer for using ADS5294 device.

    Let's talk about the Channel Averaging register settings first.

    Assume the customer is trying to use the following example:

    1) First of all, the customer needs to set:

        EN_CHANNEL_AVG to be Address=0x29, Data=0x0001

    2)  If the customer wants to average ADC1 and ADC2 data

        and send these averaged data out to LVDS output OUT1.

         Also, if the customer wants to average ADC3 and ADC4 data

        and send these averaged data out to LVDS output OUT4.

        Note: assume both LVDS output OUT2 and OUT3 are not used in this case.

        Please set the following register: Address=0x2C, Data=0x0402

    Then, you can capture the digital output data

    for (ADC1+ADC2)/2 average shown at output OUT1

    and (ADC3+ADC4)/2 average shown at output OUT4.

    Please look at the following settings. Thanks!

    Thank you!

    Best regards,

    Chen

  • Chen,

    Thank you, I am doing well and I hope its the same with you.

    Thank you very much for the support. I will get back to once I have an feed back from the customer.

    Thanks,
    Needhu
  • Hi Needhu,

    How are you?

    For the ADS5294 device digital filter settings,

    please take a look at the following example:

    Assume the customer tries to use the built-in low pass filter (Set 3)

    inside the ADC Channel 1 with the Decimation by 4.

    Then the customer needs to set up ADS5294 registers for ADC Channel 1 as shown as below:

    1) First, please enable GLOBAL_EN_FILTER as: Address=0x29, Data=0x0002

    2) Then please set the register for ADC Channel 1's filter settings as:

         Address=0x2E, Data=0x0111

    Here shows our bench settings using TSW1400 EVM for ADS5294 EVM.

    3) When we run the TSW1400 GUI to observe ADS5294 Ch1,

    we can see the following noise floor with low pass filter=ON.

    In this case we have not changed any Output Data Rate yet.

    Therefore the output data rate = 80MHz.

    4) Then please set the Output Data Rate to be 1/4 of ADC sampling rate as:

        Address=0x38, Data=0x0002

        When we run the TSW1400 GUI to observe ADS5294 Ch1,

    we can see the following noise floor with low pass filter=ON (the same)

    also In this case we have changed the output data rate = 20MHz.

    So here is the total settings.

    Please take a look:

    That are all the settings.

    Thank you very much for helping the customer.

    Have a nice day!

    Best regards,

    Chen

  • Chen,

    Thank you very much for your support :)

    Best,
    Needhu