Honored Contributor
Honored ContributorI read from the quoted handbook statetement, that the carry chain is correctly used with LPM functions, (e.g. adder), which can be confirmed, or speacial functions are needed, which apparently means low-level primitives.
I used cycloneiii_lcell_comb, which also corresponds to the suggestion in the Advanced Synthesis Handbook, that WYSIWYG primitives are the clearest way to specify carry in- and outputs explicitely. With the lcell_comb WYSIWYG primitives, arithmetic mode is automatically used, if you connect cout. P.S.: As a special point with WYSIWYG primitives you have to specify the LUT function by a binary mask. I was able to figure out some codes needed for my tests with Cyclone III, but was wondering if there is any complete document. Now I noticed a comment in a Cookbook file (arithmetic/basic_adder.v): --- Quote Start --- Detailed information on the programming of WYSIWYG cells is available through the Altera University Program (for CAD tools research). --- Quote End --- Does anyone know about the details?
