DFT & FF without resets

[ivlsi]

DFT & Flops without resets

Hi All,

I need to implement a FIFO (a piece of memory) using Flip Flops.

For functionality of the block, there is no need to use flops with a reset for this FIFO. But what's from DFT point of view? Will it be a trouble to handle these flops without reset from DFT point of view?

Thank you!

 

[artmalik]

Reset is not a necessity for DFT...majority of the flops used in a design are not resettable. From a DFT point of there is no requirement for using resettable flops.

 

[harpv]

Reset is not a necessity for DFT...majority of the flops used in a design are not resettable. From a DFT point of there is no requirement for using resettable flops.

I don't understand this. But isn't it required that all the flops be made resettable, since during scan you'll need to reset all the flops to a known state before shifting in the scan pattern? If the FIFO is to be made using Flip flops shouldn't they be part of a scan chain?

 

[artmalik]

you can always flush the scan chain with a certain known pattern..... there is no requirement of flops being resettable.
one example of this ...when designing a State machine... it is possible that the State machine can get stuck in state from which it cant recover so it makes sense to reset the flops to a known state and then start using the state machine.