Altera QDRII SRAM Controller MegaCore Function Instrukcja Użytkownika Pobierz pdf (Strona 49)

Altera Corporation MegaCore Version 9.1 3–17

November 2009 QDRII SRAM Controller MegaCore Function User Guide

Functional Description

Figure 3–14 shows the behavior of a single read request for a burst of four

(wide mode). The read occurs on the Avalon interface, the slave issues a

latent read answer. The read command is sent to the memory with the

address.

Figure 3–14. Isolated Read—Burst of Four (Wide Mode)

Burst

Bursts only apply to burst of four, (narrow mode), refer to Figure 3–15 on

page 3–18. For the other two modes, there is no such concept as all the

data required on the QDRII SRAM interface is available for a single

Avalon read. The burst consists of two consecutive read requests. The

controller sends one read request to the memory, which returns the four

half cycles of value. After resynchronization, the data is sent back to the

Avalon interface.

avl_clk

avl_read

avl_data_rd[19:0]

avl_wait_request_rd

avl_data_read_valid

avl_data_rd[17:0]

qdrii_k

qdrii_a[19:0]

qdrii_rpsn

qdrii_cq

qdrii_cqn

qdrii_q[17:0]

00010001

0102030401020304

00010001

01 02 03 0404

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 67 68

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Altera QDRII SRAM Controller MegaCore Function Instrukcja Użytkownika Strona 49