16-50
MPC860 PowerQUICC UserÕs Manual
MOTOROLA
Part IV. Hardware Interface
driven in this state until the LAST bit is set in a RAM word. The TODT bit is relevant only
in words read by the UPM after AS is negated.
For a comprehensive discussion of external bus interfacing, see Section 16.8, ÒExternal
Master Support.Ó
Figure 16-46. Wait Mechanism Timing for an External Asynchronous Master
16.7 Handling Devices with Slow or Variable Access
Times
The memory controller provides two ways to interface with slave devices that are very slow
(access time is greater than the maximum allowed by the user programming model) or
cannot guarantee a predeÞned access time (for example some FIFO, hierarchical bus
interface, or dual-port memory devices). These mechanisms are as follows:
¥
The wait mechanismÑUsed only in accesses controlled by the UPM.
MAMR[GPLA4DIS] and MBMR[GPLB4DIS] enable this mechanism.
¥
The external TA mechanism is used only in accesses controlled by the GPCM.
ORx[SETA] speciÞes whether TA is generated internally or externally.
The following examples show how the two mechanisms work.
GCLK2_50
CSx
GPL1
TA
WAEN
AS
C11
C10
C9
C8
C7
C6
C5
C4
C3
C2
C1
GCLK1_50
CLKOUT
E
D
C
B
A
RAM
Word N
RAM
Word N + 1
RAM
Word N + 2
WAIT
WAIT
RAM
Word N
AA
BB
CC
DD
C12
F
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
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Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
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Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
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Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
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