Chapter 9. SDRAM Controller
9-11
Performance
After power-down completes, SDCR[SLEEP] is set, the SDRAM clock output is driven
high, and SDCLKE is driven low.
To wake up the SDRAMs, SDCR[GSL] must be cleared. SDCR[SLEEP] remains set while
the SDRAM is exiting sleep mode and is cleared when the SDRAM completes the correct
sequence to exit sleep mode.
9.8 Performance
The maximum performance of the SDRAM controller is determined by the required
number of cycles for page activation and precharge. The read access is influenced by the
CAS latency. All SDRAM accesses are in page mode. The following table shows the
number of required cycles including all dead cycles for each type of read/write SDRAM
access. It assumes default timing configuration using an at least PC100-compliant SDRAM
device at 66 MHz. Page miss latency includes the cycles to precharge the last open page
and activate the new page before the read/write access. There are no precharge cycles when
an address hits an open page.
In Table 9-9, the timing configuration is RTP = 61, RC = negligible, RCD = 0 (or 1), RP = 1
(or 0), and CLT = 1.
In Table 9-10, the timing configuration is RTP = 61, RC = negligible, RCD = 0, RP = 0, and
CLT = 1.
Table 9-9. SDRAM Controller Performance, 32-Bit Port, (RCD = 0, RP = 1) or
(RCD = 1, RP = 0)
SDRAM Access
Number of System Clock Cycles
REG = 0, INV = 0
REG = 1, INV = 0
Single-beat read
Page miss
8
9
Page hit
5
6
Single-beat write
Page miss
6
6
Page hit
3
3
Burst read
Page miss
8-1-1-1 = 11
9-1-1-1 = 12
Page hit
5-1-1-1 = 8
6-1-1-1 = 9
Burst write
Page miss
6-1-1-1 = 9
6-1-1-1 = 9
Page hit
3-1-1-1 = 6
3-1-1-1 = 6
Table 9-10. SDRAM Controller Performance, 32–Bit Port, (RCD = 0, RP = 0)
SDRAM Access
Number of System Clock Cycles
REG = 0, INV = 0
REG = 0, INV = 0
Single-beat read
Page miss
7
8
Page hit
5
6
Содержание DigitalDNA ColdFire MCF5272
Страница 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Страница 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Страница 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
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Страница 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Страница 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Страница 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Страница 338: ...13 44 MCF5272 User s Manual Application Examples ...
Страница 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Страница 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Страница 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Страница 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...
Страница 548: ...INDEX Index 12 MCF5272 User s Manual ...