Forum Discussion
GOMEZ_IT
Occasional Contributor
Occasional Contributorreg~feeder REMOVE?
Good morning.
I'm trying to make 2-register synchronizers for the metstability problem on asynchronous signals.
Quartus automatically inserts the LUT between one register and another which calls regx...
FvM
Super Contributor
Super ContributorHi,
I made an experiment with Cyclone 10 LP:
1. Implemented a register chain with cyclone10lp_ff wysiwyg primitives
2. Implemented a register chain with lpm_shiftreg
In both cases, datapath still goes through logic_cell_comb "reg feeder".
My guess, register chain path will be only used if logic_cell_comb is needed for other logic. Or it's not used by present Quartus versions at all.
GOMEZ_ITOccasional Contributor
Occasional ContributorHI,
I also experimented with the wysiwyg primitives for cycloneive and
I confirm that the feeder is always inserted with quartus_std_22.1.
And trying to use certain pins of the flip-flop,
like sdata/sload, to try to force not to use the feeder,
quartus still ignores the mode in which I instantiated the primitive flipflop
and connects it as he wants, without giving errors or warnings!!
