mpc823rg Freescale Semiconductor, Inc, mpc823rg Datasheet - Page 350

• Manufacturer Part Number: mpc823rg
• Description: Mpc823 Powerquicc Integrated Communications Processor For Portable Systems
• Manufacturer: Freescale Semiconductor, Inc

External Bus Interface
When a burst access is initiated by the MPC823, the bus interface only recognizes the
RETRY assertion as a retry termination if it detects it before the first data beat is
acknowledged by the slave device. When the RETRY signal is asserted as a termination
signal on the second or third data beat of the access, the MPC823 recognizes it as a transfer
error acknowledgement. If a “non burst” access to a small port size device is initiated by the
MPC823, the transfer size of the access is bigger than the slave port size, and the first
transfer of this access is normally acknowledged by the assertion of TA, the MPC823
initiates the following “single beat” transfers to complete the access and recognize the
RETRY assertion as a transfer error acknowledge.
CLKOUT
BR
BG(OUTPUT)
BB
A[6:31]
RD/WR
TSIZ[0:1]
BURST
TS
DATA
TA
RETRY
BI
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A
Figure 13-30. Retry On Burst Cycle
MPC823 REFERENCE MANUAL
CAUSE TRANSFER ERROR
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IF ASSERTED WILL
ALLOW EXTERNAL MASTER
TO GAIN THE BUS
A
MOTOROLA