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What tool are you using? A commercial tool or writing your own?
Check out this site if you need those circuits in Verilog format:
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wjccentury,
Not sure if there is such command in DFT compiler, but you can use the following command in Tetramax after an ATPG run:
report_fault -class <fault_class> -l <n> <m>
where <fault_class> is one of the fault classes listed in Tetramax fault coverage report (I usually put AN...
Verification is to check whether a chip is designed to its functional specification. Once the functionality is verified, the design can be sent out to fabrication.
During fabrication, some chips will end up with defect (just like any manufacturing process). The goal of testing is to sort out...
In capture mode, the data lockup latch on the scan chain does not matter, since SE is 0. I hope you are not adding data lockup latches into you normal data path, since this will mess up your functional timing.
In shift mode, assuming you have the following:
FF1->LAT->FF2
STA should check hold...
scan edge
shalal,
Almost all scan insertion tools that I know of don't have any information about delays or clock skews, so scan insertion tools will not insert data lockup latches if it they are clock by the same clock source.
If the skew is small, then you should leave it to the backend tool...
Eric,
If the 2 clock domains are fully controllable from chip pins, you can false path them, and tweak the timing on the ATE.
If the 2 clock domains are muxed into one bypass clock, then create_clock at the common bypass clock in STA with your reduced scan frequency, constrain it to scan mode...
shahal, leeguoxian,
Frequency of operation is not as important during scan shifting. Therefore, we can always slow down the freq and/or modify the duty cycle to remove a hold time problem with data lockup latches.
If your skew is big, then you will need a lot of buffers or delay cells, which is...
why add lockup latch end scan chain
Depends on your clock waveform. If your clock waveform is return-to-zero (0->1->0), then negedge should be first. If your clock is return-to-one (1->0->1), then posedge should be first.
The reason is because you don't want a scan data to hop across 2...
Theoretically speaking, you can figure out the clock insertion delays to every flip-flop, sort the clock insertion delays from the longest to the shortest, and reordered the scan chains accordingly. This will guarantee that there is no hold time violations, assuming that the hold time...
I see your confusion now.
This pattern is detecting SA0 on SE pin. Although you may argue that the shift cycle should already cover this, a combinational ATPG does not count on it.
Even though an ATPG tool will simulate the shift process to make sure the chain is intact, it does NOT usually do...
leeguoxian,
SE=1 during shift, not capture.
During capture, SE=0 which selects the D path to be captured. If there is a SA1 fault on SE, the SI pin will be selected instead. So detect a SA1 fault on SE, we need to be in capture mode (SE=0) and D has to be different from SI.
Re: Some problems about SCAN Insertion, wlecome to discuss t
Logically, there is not much difference. If you are stitching with DFT compiler, all you need is to not declare the netlist as test_ready for a netlist that was not synthesized with the "-scan" option.
The main difference though is...
If there is a SA0 on SE pin, shift pattern will detect it immediately. However, if there is a SA1, the only way to detect it is when D pin is different from SI pin, which in general may be easy to achieve, but not always without the proper pattern on D.
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