10-46
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part III. The Hardware Interface
10.4.8 SDRAM Read/Write Transactions
The SDRAM interface supports the following read/write transactions:
¥
Single-beat reads/writes up to double word size
¥
Bursts of two, three, or four double words
SDRAM devices perform bursts for each transaction, the burst length depends on the port
size. For 64-bit port size, it is a burst of 4. For 32-bit port size, it is a burst of 8. For reads
that require less than the full burst length, extraneous data in the burst is ignored. For writes
that require less than the full burst length, the MPC8260 protects non-targeted addresses by
driving DQM
n
high on the irrelevant cycles of the burst. However, system performance is
not compromised since, if a new transaction is pending, the MPC8260 begins executing it
immediately, effectively terminating the burst early.
10.4.9 SDRAM M
ODE
-S
ET
Command Timing
The MPC8260 transfers mode register data (CAS latency, burst length, burst type) stored
in P/LSDMR[SDMODE] to the SDRAM array by issuing the
MODE
-
SET
command.
Figure 10-37 shows timing for the
MODE
-
SET
command.
Figure 10-37. SDRAM M
ODE
-S
ET
Command Timing
Figure 10-38 shows mode data bit settings.
CLK
ALE
CS
SDRAS
SDCAS
MA[0Ð11]
WE
DQM
Data
Z
Z
D0
D1
D2
D3
*Mode Data
Row
Column
*The mode data is the address value during a mode-set cycle. It is driven by the memory controller, in single
MPC8260 mode, according to P/LSDMR[CL] register. In 60x-compatible mode, software must drive the correct
value on the address lines. Figure 10-38 shows the actual value.
Mode Set
Page Activate
Write (Burst)
Summary of Contents for MPC8260 PowerQUICC II
Page 1: ...MPC8260UM D 4 1999 Rev 0 MPC8260 PowerQUICC II UserÕs Manual ª ª ...
Page 66: ...lxvi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA ...
Page 88: ...1 18 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 120: ...2 32 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part I Overview ...
Page 138: ...Part II iv MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II Configuration and Reset ...
Page 184: ...4 46 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part II ConÞguration and Reset ...
Page 202: ...Part III vi MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 266: ...8 34 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 382: ...10 106 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 392: ...11 10 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part III The Hardware Interface ...
Page 430: ...Part IV viii MOTOROLA Part IV Communications Processor Module ...
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Page 980: ...A 4 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Appendixes ...
Page 1002: ...Index 22 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA INDEX ...
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