MMC2001
EXTERNAL INTERFACE MODULE
MOTOROLA
REFERENCE MANUAL
7-1
SECTION 7
EXTERNAL INTERFACE MODULE
7.1 Overview
The external interface module (EIM) handles the interface to devices external to the
MMC2001, including generation of chip selects for external peripherals and memory.
It provides the following features:
• Four chip selects for external devices, each covering a range of 16 Mbytes
• Programmable wait-state generator for each chip select
• Selectable protection for each chip select
• Programmable data port size for each chip select
• Control for external/internal boot ROM device selection
• Bus watchdog counter for all bus cycles
• Programmable general output capability for unused chip select outputs
• Show cycles to allow internal bus cycles to be monitored externally
Figure 7-1 EIM Block Diagram
7.2 Signals
7.2.1 Address Bus
The ADDR[19:0] signals are address bus outputs used to address external devices.
Inte
rnal
Bu
s
CS0
CS1
CS2
CS3
TA, TEA
DATA[31:0]
ADDR[31:0], R/W, TSIZ, TC
ADDR[19:0]
EB[0:1]
OE
R/W
DATA[15:0]
MOD
TREQ, TBUSY, ABORT
MOD
Module
Timer/Reset
EIM
Freescale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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