Chapter 6. MPC8240 Memory Interface
6-21
SDRAM Interface Operation
6.2.7.1 SDRAM Paging in Sleep Mode
Systems attempting to go to sleep with SDRAM paging enabled must ensure that the
following sequence of events occurs in software before the processor core enters sleep
mode:
•
Disable page mode by writing 0x00 to MPMR[PGMAX].
•
Wait for any open pages to close by allowing a SDRAM refresh interval to elapse;
MCCR[REFINT], bits (15:2)
•
Processor core enters sleep mode.
Upon waking from sleep, software must perform the following sequence to re-enable
paging (if so desired).
•
Awake from sleep
•
Enable page mode by writing the appropriate maximum page open interval based
upon the system design to MPMR[PGMAX] (optional).
6.2.8 SDRAM Interface Timing
To accommodate available memory technology across a wide spectrum of operating
frequencies, the MPC8240 allows the following SDRAM interface timing intervals to be
programmable with granularity of 1 memory clock cycle:
•
RDLAT—internal processor core bus data latency from read command
•
REFREC—refresh command to activate command interval
•
ACTORW—activate command to read or write command interval
•
ACTOPRE—activate command to precharge command interval
•
PRETOACT—precharge command to activate command interval
•
BSTOPRE—burst to precharge command interval (page open interval)
The SDRAM interface timing intervals are defined in Table 6-11.
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...