Chapter 9 SDRAM Controller
9-9
9.3.3 Initialization
of
SDRAM
The TX4937 Command Register has functions for generating the cycles required for initializing
SDRAM. Using software to set each register makes it possible to execute initial settings at a particular
timing.
1
Set the SDRAM Channel Control Register (SDCCRn).
2
Set the SDRAM Timing Register (SDCTR). This timing setting is applied to all channels, so please
set it to the slowest memory device.
3
Use the SDRAM Command Register (SDCCMD) to issue the Pre-charge All command.
4
Issue the Set Mode Register command in the same manner.
5
Set the refresh count required to initialize SDRAM to the refresh counter (SDCTR.RC)
1
and set the
refresh cycle (SDCTR.RP).
2
3
6
Wait until the refresh counter returns to “0.”
7
Set the refresh cycle (SDCTR.RP) to the proper value.
1
The number of refresh operations can be counted using the refresh counter. With this function, it is no longer
necessary to assemble special timing groups in the software when counting refresh operations.
2
Setting the refresh cycle to a small value makes it possible to expedite completion of the refresh cycle required for
SDRAM initialization. As described above, please set normal values after the required number of refresh cycles have
been generated.
3
Refresh requests have priority over all other SDRAM Controller access requests. Please do not set the memory
refresh cycle to an unnecessarily short value.
Summary of Contents for TX49 TMPR4937
Page 1: ...64 Bit TX System RISC TX49 Family TMPR4937 Rev 2 0 ...
Page 4: ......
Page 13: ...Table of Contents ix TMPR4937 Revision History 1 ...
Page 14: ...Table of Contents x ...
Page 15: ...Handling Precautions ...
Page 16: ......
Page 18: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 40: ...3 General Safety Precautions and Usage Considerations 3 18 ...
Page 42: ...4 Precautions and Usage Considerations 4 2 ...
Page 43: ...TMPR4937 2005 3 Rev 2 0 ...
Page 44: ......
Page 52: ...Chapter 1 Overview and Features 1 6 ...
Page 156: ...Chapter 7 External Bus Controller 7 56 ...
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Page 506: ...Chapter 20 Extended EJTAG Interface 20 8 ...
Page 530: ...Chapter 22 Pinout and Package Information 22 10 ...
Page 542: ...Chapter 24 Parts Number when Ordering 24 2 ...