![Freescale Semiconductor MCF54455 Reference Manual Download Page 455](http://html1.mh-extra.com/html/freescale-semiconductor/mcf54455/mcf54455_reference-manual_2330541455.webp)
FlexBus
20-2
Freescale Semiconductor
•
Byte-, word-, longword-, and 16-byte line-sized transfers
•
Programmable burst- and burst-inhibited transfers selectable for each chip select and transfer
direction
•
Programmable address-setup time with respect to the assertion of chip select
•
Programmable address-hold time with respect to the negation of chip select and transfer direction
20.1.3
Modes of Operation
The external interface is a configurable multiplexed bus set to one of the following modes:
NOTE
While using non-multiplexed 32-bit mode, the PCI address/data bus is used
as the FlexBus address bus. See
Chapter 11, “Chip Configuration Module
for more information.
20.2
External Signals
This section describes the external signals involved in data-transfer operations.
•
Multiplexed 32-bit address and 32-bit data
•
Multiplexed 32-bit address and 16-bit data (non-multiplexed 16-bit address and 16-bit data)
•
Multiplexed 32-bit address and 8-bit data (non-multiplexed 24-bit address and 8-bit data)
•
Non-multiplexed 32-bit address with 32-bit data
Table 20-1. FlexBus Signal Summary
Signal Name
I/O
1
Description
FB_A[31:0]
O
In a non-multiplexed configuration: Address bus.
In a multiplexed configuration: Not used.
FB_D[31:0]
I/O
In a non-multiplexed configuration: Data bus.
In a multiplexed configuration: Address/data bus, FB_AD[31:0].
FB_CS[5:0]
O
General purpose chip-selects. The actual number of chip selects available
depends upon the device and its pin configuration. See
for more details.
FB_BE/BWE[3:0]
O
Byte enable/byte write enable
FB_OE
O
Output enable
FB_R/W
O
Read/write. 1 = Read, 0 = Write
FB_ALE
O
Address latch enable
FB_TSIZ[1:0]
O
Transfer size
FB_TBST
O
Burst transfer indicator
FB_TA
I
Transfer acknowledge
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...