Honored ContributorI'm using an altlvds_rx receiver in Cyclone III with external PLL. For the buffer implementation I can choose between RAM, MUX and LE. Could there be a reason to make a choice other than resource usage?
There's no documentation on this issue available. Well, at least I can't find it. Cheers, Ton
Honored ContributorWell there's one good reason not to use RAM buffer. It adds a variable data latency to rx_out after a reset or power cycle.
The MUX and LE and they both give a FIXED latency of 3 slow clock periods. The LE buffer implementation uses a lot of resources, so I stick with the MUX buffer implementation. See also another thread I've posted today. Cheers, TonHonored ContributorMany ALT_LVDS users probably wonder what's the purpose of a buffer with Cylone III LVDS, because they never got in touch with it. Actually, it's only present with odd deserialization factors.
I once had the bad idea to build a desrialization factor 14 LVDS receiver (which is not supported by the MegaFunction directly) from a "factor 7" block. But the behaviour of the odd deserialization factor receiver was so strange, that I preferred an own deserializer design.Honored ContributorThanks FvM. So it is the odd deserialization factor. You're right. I use a deserialization factor of 9. What a mistake. Next time I will certainly use even factors, that's for sure.
Do you know if there's any detailed additional information on this topic? Cheers, TonHonored Contributor
