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ADS7230: How can we get he bit of TAG to distinguish which channel the data is generated from?

Lian Wu
Genius 5250 points
Part Number: ADS7230

Dears：

How can we get he bit of TAG to distinguish which channel the data is generated from? Now the TAG is always '0'.

Customer used ADS7230 dual-channel data collection, and did not configure ADS7230, which is the default configuration of power on ADS7230.

And can get the correct AD data.

Pls. give some advice about it? And the schematic as follows:

  • 0
    TI__Mastermind 40950 points

    Hello Luck,

    The power-on reset should default to auto channel select with the TAG bit enabled.  Please note that you must read the TAG bit on the 17th SCLK, 12b conversion result + 4 zeros + TAG.  Is it possible the customer is reading the TAG on the 13th SCLK?  If so, it will always read zero.

    Figure 5 shows the relative timing.

    If possible, please send waveform capture for /CS, SCLK, SDO, and SDI and I can verify if the timing specs are being met.

    Thank you.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    Genius 5250 points

    Hi Keith:

    Customer has check the CLK end 24th, and there is no TAG.

    Pls. refer the below waveform and give some advice:

    1. /CS & SCLK

    2. SCLK & DATA

  • 0 in reply to Lian Wu
    TI__Mastermind 40950 points

    Hi Luck,

    The waveforms look good.  Can you ask the customer to provide plots for /CS, EOC, and the SDI pin?

    Regards,
    Keith

  • 0 in reply to Keith Nicholas
    Genius 5250 points

    Hi Keith:

    Pls. refer the below pictures:

    1. CLK & SDI

    2. CONVST  &  EOC

    3. EOC & CS

  • 0 in reply to Lian Wu
    TI__Mastermind 40950 points

    Hello Luck,

    All of these waveforms look correct.

    Has the customer taken multiple measurements, 4 or more consecutive, and verified that the input channel is correctly switching between channel0 and channel1?  Please ask the customer to set channel0 to full scale (5V) and channel1 to zero (0V) and capture at least 4 consecutive measurements.

    Also, it is possible that the power-on reset circuit is not operating correctly (Figure 67 in the datasheet).  After power-up, please issue a software reset by writing to the CFR register:

    The 24b transfer on SDI would be:

    0x1110 1111 1111 1110 0000 0000b

    Thank you,

    Keith

  • 0 in reply to Keith Nicholas
    TI__Mastermind 40950 points

    Hello Luck,

    I have not heard back from you in some time.  I am going to close this thread, but if the customer has further questions, please feel free to start a new e2e thread.

    Thank you,

    Keith