Synchronous DRAM Controller Module
MCF5253 Reference Manual, Rev. 1
7-12
Freescale Semiconductor
Figure 7-7. Burst Write SDRAM Access
Accesses in synchronous burst page mode always cause the following sequence:
1.
ACTV
command
2.
NOP
commands to assure SRAS-to-SCAS delay (if CAS latency is 1, there are no
NOP
commands)
3. Required number of
READ
or
WRITE
commands to service the transfer size with the given port size
4. Some transfers need more
NOP
commands to assure the
ACTV
-to-precharge delay
5.
PALL
command
6. Required number of idle clocks inserted to assure precharge-to-
ACTV
delay
7.4.4
Continuous Page Mode
Continuous page mode is identical to burst page mode, except that it allows the processor core to handle
successive bus cycles that hit the same page without having to close the page. When the current bus cycle
finishes, the MCF5253 core internal pipelined bus can predict whether the upcoming cycle will hit in the
same page.
•
If the next bus cycle is not pending or misses in the page, the
PALL
command is generated to the
SDRAM.
•
If the next bus cycle is pending and hits in the page, the page is left open, and the next SDRAM
access begins with a
READ
or
WRITE
command.
•
Because of the nature of the internal CPU pipeline this condition does not occur often; however,
the use of continuous page mode is recommended because it can provide a slight performance
increase.
A[31:0]
SDRAS
SDCAS
SDWE
D[31:16]
ACTV
WRITE
PALL
NOP
SD_CS0
XDQM
t
CASL
= 2
Row
Column
Column Column
Column
t
RP
t
RWL
BCLK
NOP
Summary of Contents for MCF5253
Page 1: ...Document Number MCF5253RM Rev 1 08 2008 MCF5253 Reference Manual...
Page 26: ...MCF5253 Reference Manual Rev 1 xxvi Freescale Semiconductor...
Page 32: ...MCF5253 Reference Manual Rev 1 xxxii Freescale Semiconductor...
Page 46: ...MCF5253 Introduction MCF5253 Reference Manual Rev 1 1 14 Freescale Semiconductor...
Page 62: ...Signal Description MCF5253 Reference Manual Rev 1 2 16 Freescale Semiconductor...
Page 98: ...Instruction Cache MCF5253 Reference Manual Rev 1 5 10 Freescale Semiconductor...
Page 104: ...Static RAM SRAM MCF5253 Reference Manual Rev 1 6 6 Freescale Semiconductor...
Page 128: ...Synchronous DRAM Controller Module MCF5253 Reference Manual Rev 1 7 24 Freescale Semiconductor...
Page 144: ...Bus Operation MCF5253 Reference Manual Rev 1 8 16 Freescale Semiconductor...
Page 176: ...System Integration Module SIM MCF5253 Reference Manual Rev 1 9 32 Freescale Semiconductor...
Page 198: ...Analog to Digital Converter ADC MCF5253 Reference Manual Rev 1 12 6 Freescale Semiconductor...
Page 246: ...DMA Controller MCF5253 Reference Manual Rev 1 14 18 Freescale Semiconductor...
Page 282: ...UART Modules MCF5253 Reference Manual Rev 1 15 36 Freescale Semiconductor...
Page 344: ...Audio Interface Module AIM MCF5253 Reference Manual Rev 1 17 46 Freescale Semiconductor...
Page 362: ...I2 C Modules MCF5253 Reference Manual Rev 1 18 18 Freescale Semiconductor...
Page 370: ...Boot ROM MCF5253 Reference Manual Rev 1 19 8 Freescale Semiconductor...
