CS5920 datasheet(131/160 Pages) AMCC

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S5920 – PCI Product

Revision 1.01 – November 28, 2005

AMCC Confidential and Proprietary

DS1596

131

Data Book

On bus signals PTATN#, PTBURST#, PTNUM[1:0],

PTWR and PTBE[3:0] will update on the next ADCLK.

Clock 1:

Pass-Thru signals PTATN#, PTBURST#,

PTNUM[1:0], PTWR and PTBE[3:0] are driven to indi-

cate what action is required by Add-On logic. These

status signals are valid only when PTATN# is active.

Add-On logic can decode status signals upon the

assertion of PTATN#.

PTATN# Asserted. Indicates Pass-Thru access is

pending.

PTBURST# Asserted. The access has multiple data

phases.

PTNUM[1:0] 0h. Indicates the access is to Pass-Thru

region 0.

PTWR Asserted. Indicates the access is a write.

PTBE[3:0]# 0h. Indicates valid bytes for the first data

transfer.

Clock 2:

The Add-On sees that a burst-write is being

requested by the PCI, so starts by reading the corre-

sponding address via PTADR#. Note that all 32 bits of

the APTA are output on the DQ bus when PTADR# is

asserted. The Add-On must be capable of latching the

upper 24 bits (if needed). The Add-On begins reading

the APTD Register (asserting SELECT#, ADR[6:2],

and RD#). The Add-On logic sees that all bytes are

valid (PTBE# = 0h), so starts the read by asserting

BE0#, to indicate that BYTE0 of the APTD is to be

driven on DQ[7:0] during the next clock cycle.

Clock 3:

The Add-On logic latches the Pass-Thru

address. RD# and BE0# are sampled by the S5920,

so BYTE0 of the APTD is driven on DQ[7:0] and

PTBE0# is deasserted. The Add-On asserts RD# and

BE1#, thus requesting that BYTE1 of the APTD be

driven on the DQ bus during the next cycle.

Clock 4:

The Add-On logic latches BYTE0. RD# and

BE1# are sampled asserted by the S5920, so BYTE1

of the APTD is driven on DQ[7:0] and PTBE1# is deas-

serted. The Add-On device asserts RD# and BE2#,

thus requesting that BYTE2 of the APTD be driven on

the DQ bus during the next cycle.

Figure 69. PCI to Add-On Passive Write to an 8-bit

ADCLK

PTATN#

PTBURST#

PTNUM[1:0]

PTWR

PTBE[3:0]#

SELECT#

ADR[6:2]

BE[3:0]#

RD#

DQ[7:0]

PTADR#

ADD[7:0]

PTRDY#

9Ah

D4h

DQ[31:8]

ADD[31:8]

2Ch

30h

08h

AAh

BBh

CCh

DDh

CS5920 数据表(PDF) 131 Page - Applied Micro Circuits Corporation

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