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AR# 25115

9.1i Virtex-5 MAP - How do I constrain two RAMB18 symbols to the same RAMB18X2 component?

Description

I would like to constrain two RAMB18 symbols to the same RAMB18X2 block RAM component without locking them to a particular site. I understand that BEL constraints can be used to do this, but what values should I use?

Solution

RAMB18 symbols can be constrained with BEL values of "LOWER" and "UPPER." The following is an example of the UCF syntax needed:

INST "v5_emac_ll/client_side_FIFO_emac0/tx_fifo_i/ramgen_l" BEL = LOWER ;

INST "v5_emac_ll/client_side_FIFO_emac0/tx_fifo_i/ramgen_u" BEL = UPPER ;

AR# 25115
Date 12/15/2012
Status Active
Type General Article