Chapter 4. Configuration Registers
4-51
Memory Control Configuration Registers
Figure 4-32 and Table 4-41 show memory control configuration register 4 (MCCR4)
format and bit settings.
Figure 4-32. Memory Control Configuration Register 4 (MCCR4)—0xFC
5–3
RCD
2
000
RAS to CAS delay interval. For DRAM/EDO only. These bits control the
number of clock cycles between the assertion of RAS and the first assertion of
CAS. The value for RCD
2
depends on the specific DRAMs used and the
frequency of the memory interface. However, RCD
2
must be at least two clock
cycles. See Section 6.3.5, “FPM or EDO DRAM Interface Timing,” for more
information.
001 Reserved
010 2 clocks
011 3 clocks
...
...
111 7 clocks
000 8 clocks
2–0
RP
1
000
RAS precharge interval. For DRAM/EDO only. These bits control the number
of clock cycles that RAS must be held negated (to allow for row precharge)
before the next assertion of RAS. Note that RP
1
must be at least two clock
cycles and no greater than 5 clock cycles. See Section 6.3.5, “FPM or EDO
DRAM Interface Timing,” for more information.
010 2 clocks
011 3 clocks
110 4 clocks
101 5 clocks
All others: reserved
Table 4-40. Bit Settings for MCCR3—0xF8 (Continued)
Bits
Name
Reset
Value
Description
ACTOPRE
0
0 0
SDMODE
ACTORW
31
28 27
24 23 22 21 20 19 18 17 16 15 14
8
7
4
3
0
Reserved
PRETOACT
BSTOPRE[6–9]
REGDIMM
BSTOPRE[0–1]
WMODE
BUF_TYPE[0]
BUF_TYPE[1]
Содержание MPC8240
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Страница 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Страница 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Страница 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Страница 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Страница 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Страница 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Страница 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Страница 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Страница 516: ...16 14 Watchpoint Trigger Applications ...
Страница 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Страница 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Страница 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...