[SOLVED] What does shift, capture and update mean in scan design

[mailsrikanth007]

Hi,

Can anyone explain in detail what does shift, capture and update mean in scan?

I know all the flops in the design are made scannable and form a chain. Now to test the design, there is scan-in, capture and scan-out.

I can relate shift and capture here but where does update happen and what exactly does it mean?

Please advise!

 

[slutarius]

What is tool you use to make scan chain and test pattern ?
You can read the manual for knowing exactly what they mean. They depens of EDA.

 

[mailsrikanth007]

Hi,

What do you mean depend on the EDA.
Isn't capture, shift and update general terms used in scan?
Even in IEEE TAP machine there are states for capture, shift and update.
Please advise!

 

[slutarius]

Hi,

What do you mean depend on the EDA.
Isn't capture, shift and update general terms used in scan?
Even in IEEE TAP machine there are states for capture, shift and update.
Please advise!

Would you point me to where you read about update ? I am curious too.

 

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capture - samples inputs
shift - shifts the capture or update data around the scan chain
update - sets the outputs to the data that was shifted in

All of these are described in the 1149.1 document.