In the Spartan-6 Memory Controller Block (MCB) design, how many commands and how much data can be stored at a given time?
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The command path of the user interface uses a simple 4-deep FIFO structure to hold pending commands. This determines the number of commands that could be stored at a time which is 4.
The write path of the user interface uses a simple 64-deep FIFO structure to hold data in preparation for a Write transaction to memory. The stored data for write operation at a given time is 64.
The full flag (pX_cmd_full) signal from the command FIFO should be monitored when sending write commands to MCB.
The read path of the user interface uses a simple 64-deep FIFO structure to hold data returning from a Read transaction. So, the maximum number of stored read data from DDR memory is 64.
The empty flag (pX_rd_empty) from the read data FIFO can be used as a data valid indicator. The pX_rd_overflow signal indicates to the user that the memory has returned more data than it can fit into the read data FIFO and that thedata was lost.