MPC555
/
MPC556
EXTERNAL BUS INTERFACE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
9-35
Figure 9-26 Internal Bus Arbitration State Machine
9.5.7 Address Transfer Phase Signals
Address transfer phase signals include the following:
• Transfer start
• Address bus
• Transfer attributes
Transfer attributes signals include RD/WR, BURST, TSIZ[0:1], AT[0:3], STS, and
BDIP. With the exception of the BDIP, these signals are available at the same time as
the address bus.
IDLE
BG
= 1
BB
= t.s
External
BG
= 0
External Master
BR
=
0
Ext Master
Release Bus
BG
= 1
BB
= t.s
BB
= t.s
BB
= 0
BG
= 1
BB
= 0
BB
= 1
B
B
=
1,
BR
=1
BR = 0
Requests Bus
BR
= 1
External Device With Higher
Priority than the Current Internal
Bus Master Requests the Bus
Internal Master With Higher
Priority than the External Device
Requires the Bus
MCU Needs
No Longer
the Bus
Needs the Bus
Still Needs
the Bus
Wait
Owner
Owner
Bus
MPC555 /
MPC556
MPC555 / MPC556
MPC555 /
MPC556
MPC555 /
MPC556
MPC555 /
MPC556
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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