Slowport; Generic Slowport Connection - Intel IXP28XX Manual

Slowport

Note: To meet interface timing requirements, Intel suggests the external interface logic be implemented
Figure 74.
Hardware Design Guide
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The Slowport is an external interface to the Intel
and is used for 8-bit flash PROM access and 8-, 16-, or 32-bit microprocessor device access. The
Slowport allows the Intel XScale
devices. The Slowport supports 4-, 8-, and 16-Mbyte flash sizes.
The address bus and data bus are multiplexed to reduce the pin count and 24 bits of address are
shifted out on three clock cycles. Therefore, an external set of buffers is needed to latch the
address; two chip selects are provided – see
in a high speed CPLD (Complex Programmable Logic Device), as shown in

Generic Slowport Connection

SP_RD_L
SP_WR_L
SP_CS_L[0]
SP_CS_L[1]
SP_A[1:0]
SP_AD[7:0]
SP_ALE_L
Clock
SP_CLK
Driver
CY2305
®
Intel
IXP2800
Network
Processor
SP_ACK_L
®
IXP2800 or Intel
®
core to perform read/write data transfers to external slave
Figure 74 (note that the ACK signal is optional).
CE# D[7:0]
74f377
CP Q[7:0]
A[24:18]
CE# D[7:0]
74f377
CP Q[7:0]
A[17:10]
CE# D[7:0]
74f377
CP Q[7:0]
A[9:2]
IXP28XX Network Processor
Slowport
®
IXP2850 Network Processor,
Figure 77.
OE_L
WE_L
CS_L
A[1:0]
D[7:0]
A[24:2]
A[24:2]
OE_L
WE_L
CS_L
A[1:0]
D[7:0]
ACK_L
A9318-02
7
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