TPS6594-Q1: Sequence of question generation

Hello Manisha,

I'm so sorry for the late reply and I understand the confusion with the WD Q&A section of the datasheet. Lots of information covered in a very small section of the datasheet.

So the section in which the screenshot is posted from is on the section of how the device generates the question and if the MCU wants to generate the question.

If you're looking to service the watchdog, all you need to do is readback the registers and implement the combinational logic located in the following diagram from the datasheet:

Now for the question generation:

The question generation on the MCU can be done through the combination logic from the diagram in the initial post.

For a seed value of 4'b0000 in the LFSR, it says after the next pulse it'll be 4b'0001 and that will be the value used in the question generation.

The value in the WD_QA_LFSR is a two bit value that can be set during the configuration of the WD. WD_QA_LFSR sets the polynomial to used in the insertion of the next bit in the LFSR, the values in this sequence are then used in the combination logic quoted below and in your initial post.

Manisha Narayana Gowda said:

I also would like to know how do  X1 X2 X3 X4 changes .
Does it indicate the value of the WD_QUESTION_SEED  or it changes according to the note in the picture((1) If the current value for bits (x1, x2, x3, x4) is 4'b0000, the next value for these bits (x1, x2, x3, x4) is 4'b0001, and all further question generation begins from this value)
This documentation is very confusing.

Best Regards,

Nicholas McNamara