mcf5208 Freescale Semiconductor, Inc, mcf5208 Datasheet - Page 27

• Manufacturer Part Number: mcf5208
• Description: Mcf5208 Coldfire Microprocessor Data Sheet
• Manufacturer: Freescale Semiconductor, Inc

5.7.1
FlexBus is a multi-function external bus interface provided to interface to slave-only devices up to a
maximum bus frequency of 83.33 MHz. It can be directly connected to asynchronous or synchronous
devices such as external boot ROMs, flash memories, gate-array logic, or other simple target (slave)
devices with little or no additional circuitry. For asynchronous devices, a simple chip-select based interface
can be used. The FlexBus interface has six general purpose chip-selects (FB_CS[5:0]) that can be
configured to be distributed between the FlexBus or SDRAM memory interfaces. Chip-select FB_CS[0]
can be dedicated to boot ROM access and can be programmed to be byte (8 bits), word (16 bits), or
longword (32 bits) wide. Control signal timing is compatible with common ROM/flash memories.
Freescale Semiconductor
* The timings are also valid for inputs sampled on the negative clock edge.
FB_CLK
Inputs
FlexBus
Input Setup And Hold
FB_CLK(75MHz)
Input Rise Time
FB4
Input Fall Time
MCF5208 ColdFire
Figure 13. General Input Timing Requirements
Invalid
®
Microprocessor Data Sheet, Rev. 1
V
V
V
h
h
V
l
= V
l
= V
= V
= V
IH
IH
IL
IL
T
1.5V Valid
SETUP
1.5V
T
HOLD
1.5V
t
t
rise
fall
FB5
Invalid
Electrical Characteristics
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