MSC8113 Reference Manual, Rev. 0
12-20
Freescale Semiconductor
Memory Controller
12.2.8 SDRAM Read/Write Transactions
The SDRAM interface handles the following read/write transactions:
Single-beat reads/writes up to 64 bits (8 bytes)
Bursts of 128 bits (16 bytes), 192 bits (24 bytes), or 256 bits (32 bytes)
SDRAM devices perform bursts for each transaction. The burst length depends on the port size.
For 64-bit ports, it is a burst of 4. For 32-bit ports, it is a burst of 8. For reads that require less than
the full burst length, extraneous data in the burst is ignored. For writes that require less than the
full burst length, the MSC8113 protects non-targeted addresses by driving
PSDDQMx
high on the
irrelevant cycles of the burst. However, system performance is not compromised since the
MSC8113 immediately begins executing any pending transaction, effectively terminating the
burst early.
12.2.9 SDRAM Refresh
The memory controller supplies auto (CBR) refreshes to SDRAM according to the interval
specified in PSRT. This represents the time period required between refreshes. The value of
PSRT depends on the specific SDRAM devices and the operating frequency of the MSC8113
bus. This value should allow for a potential collision between memory accesses and refresh
cycles. The period of the refresh interval must be greater than the access time to ensure that read
and write operations complete successfully.
There are two levels of refresh request priority, low and high. The low-priority request is
generated as soon as the refresh timer expires and is granted only if no other requests to the
memory controller are pending. If the request is not granted (memory controller is busy) and the
refresh timer expires two more times, the request becomes high-priority and is served when the
current memory controller operation finishes.
12.2.10 SDRAM Signals: Device-Specific Parameters
Software must assign correct values to some device-specific parameters that can be extracted
from the data sheet. The values are stored in the ORx and PSDMR registers. These parameters
include the following:
Summary of Contents for MSC8113
Page 1: ...MSC8113 Reference Manual Tri Core 16 Bit Digital Signal Processor MSC8113RM Rev 0 May 2008 ...
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Page 56: ...MSC8113 Reference Manual Rev 0 1 28 Freescale Semiconductor MSC8113 Overview ...
Page 76: ...MSC8113 Reference Manual Rev 0 2 20 Freescale Semiconductor SC140 Core Overview ...
Page 134: ...MSC8113 Reference Manual Rev 0 4 30 Freescale Semiconductor System Interface Unit SIU ...
Page 168: ...MSC8113 Reference Manual Rev 0 6 18 Freescale Semiconductor Boot Program ...
Page 180: ...MSC8113 Reference Manual Rev 0 7 12 Freescale Semiconductor Clocks ...
Page 260: ...MSC8113 Reference Manual Rev 0 8 80 Freescale Semiconductor Memory Map ...
Page 300: ...MSC8113 Reference Manual Rev 0 9 40 Freescale Semiconductor Extended Core ...
Page 304: ...MSC8113 Reference Manual Rev 0 10 4 Freescale Semiconductor MQBus and M2 Memory ...
Page 308: ...MSC8113 Reference Manual Rev 0 11 4 Freescale Semiconductor SQBus ...
Page 590: ...MSC8113 Reference Manual Rev 0 17 46 Freescale Semiconductor Interrupt Processing ...
Page 614: ...MSC8113 Reference Manual Rev 0 18 24 Freescale Semiconductor Debugging ...
Page 622: ...MSC8113 Reference Manual Rev 0 19 8 Freescale Semiconductor Internal Peripheral Bus IPBus ...
Page 724: ...MSC8113 Reference Manual Rev 0 21 32 Freescale Semiconductor UART ...
Page 920: ...MSC8113 Reference Manual Rev 0 25 150 Freescale Semiconductor Ethernet Controller ...
Page 1171: ...MSC8113 Reference Manual Rev 0 Freescale Semiconductor C 61 EF wait_rts P 01077FFC 9F rts 71 ...
Page 1172: ...MSC8113 Reference Manual Rev 0 C 62 Freescale Semiconductor MSC8113 Boot Code ...
Page 1202: ...MSC8113 Reference Manual Rev 0 Index 30 Freescale Semiconductor Index ...