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ADS8914B: is the DATA_VAL bit cleared by chip or user

Part Number: ADS8914B

The ADS8914B has a bit in the internal registers called DATA_VAL.  When DATA_VAL is set, the chip sends a test pattern to the user instead of the ADC result. This is like a test mode so a user can check communications. When data received equals the test pattern, communication is verified.

I expected this sequence of operation

-User sets DATA_VAL bit
-Read ADS8914.  Test pattern returned.
-Read ADS8914 again.  Test pattern returned

Instead, this sequence occurs.

-User sets DATA_VAL bit
-Read ADS8914.  Test pattern returned.
-Read ADS8914 again.  ADC result returned.

Question – What clears the DATA_VAL bit in the ADS8914B?  Is the bit cleared when the test pattern registers are read? The datasheet omits what clears the bit. Is it cleared by the user, automatically in the part, another action?

  • Hi Jeff,

    The 22-bit data output word on depends on the command given in the previous frame.
    If you set DATA_VAL in frame F, F+1 will show the fixed pattern registers; and if no new command is provided in F+1, frame F+2 will show conversion results by default. If you set DATA_VAL again on the last frame F+1, then frame F+2 will show again the fixed-pattern registers.

    Best,
    Luis