Overview - Freescale Semiconductor MCF52277 Reference Manual

Chapter 13
Crossbar Switch (XBS)
13.1

Overview

This section provides information on the layout, configuration, and programming of the crossbar switch.
The crossbar switch connects the bus masters and bus slaves using a crossbar switch structure. This
structure allows bus masters to access different bus slaves simultaneously with no interference while
providing arbitration among the bus masters when they access the same slave. A variety of bus arbitration
methods and attributes may be programmed on a slave by slave basis.
The MCF5227x devices have up to five masters and three slaves (5Mx3S) connected to the crossbar
switch. The five masters are the ColdFire core, eDMA controller, LCD controller, USB OTG module, and
serial boot. The slaves are FlexBus/SDRAM controller, SRAM controller, and the peripheral bus.
Figure 13-1 is a block diagram of the MCF5227x family bus architecture showing the crossbar switch
configuration.
ColdFire eDMA LCD USB
Serial Boot
Core Controller Controller On-the-Go
Master Modules
M0 M1 M4 M6 M7
Crossbar Switch
S1 S4 S7
Slave Modules
FlexBus/SDRAM SRAM On-chip Slave
Controller Backdoor Peripherals
Figure 13-1. Bus Architecture Block Diagram
MCF52277 Reference Manual, Rev. 1
Freescale Semiconductor 13-1