Altera QDRII SRAM Controller MegaCore Function Manual do Utilizador descarregar pdf (Página 48)

3–16 MegaCore Version 9.1 Altera Corporation

QDRII SRAM Controller MegaCore Function User Guide November 2009

Interfaces & Signals

Figure 3–12. Isolated Read—Burst of Four (Narrow Mode)

Figure 3–13 shows a single read request from the Avalon interface for a

burst of two. The principle is identical to the burst of four, but all the data

bits coming back are transferred onto the Avalon interface. The timing on

the QDRII SRAM interface is slightly different as the address is only

present for half a clock cycle.

Figure 3–13. Isolated Read—Burst of Two (Wide Mode)

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

01020102

00010001

01 02 xx xxxx

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

01020102

00010001

01 0202

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Altera QDRII SRAM Controller MegaCore Function Manual do Utilizador Página 48