10-32
MPC8260 PowerQUICC II UserÕs Manual
MOTOROLA
Part III. The Hardware Interface
10.3.11 Local Bus-Assigned SDRAM Refresh Timer (LSRT)
The local bus-assigned SDRAM refresh timer register (LSRT) is shown in Figure 10-17.
Table 10-15 describes LSRT Þelds.
10.3.12 Memory Refresh Timer Prescaler Register (MPTPR)
Figure 10-18 shows the memory refresh timer prescaler register (MPTPR).
Table 10-16 describes MPTPR Þelds.
Bit
0
1
2
3
4
5
6
7
Field
LSRT
Reset
0000_0000
R/W
R/W
Addr
0x101A4
Figure 10-17. Local Bus-Assigned SDRAM Refresh Timer (LSRT)
Table 10-15. LSRT Field Descriptions
Bits
Name
Description
0Ð7
LSRT
Refresh timer period. Determines the timer period according to the following equation:
This timer generates refresh requests for all valid banks that selected a SDRAM machine assigned
to the local bus and is refresh enabled (LSDMR[RFEN] = 1). Each time the timer expires, all banks
that qualify generate a bank staggering auto refresh request using the SDRAM machine. See
Section 10.4.10, ÒSDRAM Refresh.Ó
Example: For a 25-MHz system clock and a required service rate of 15.6 µs, given
MPTPR[PTP] = 32, the LSRT value should be 12 (decimal). 12/(25 MHz/32) = 15.36 µs, which is less
than the required service period of 15.6 µs.
Bit
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Field
PTP
Ñ
Reset
0000_001x 0000_0000
R/W
R/W
Addr
0x10184
Figure 10-18. Memory Refresh Timer Prescaler Register (MPTPR)
Table 10-16. MPTPR Field Descriptions
Bits
Name
Description
0Ð7
PTP
Refresh timers prescaler. Determines the period of the memory refresh timers input clock. It divides
the system clock.
8Ð15
Ñ
Reserved, should be cleared
TimerPeriod
LSRT
F
MPTC
-----------------
è
ø
æ
ö
=
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 ...
Page 490: ...14 36 MPC8260 PowerQUICC II UserÕs Manual MOTOROLA Part IV Communications Processor Module ...
Page 524: ...17 10 MPC8260 PowerQUICC II UserÕs Manual 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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