12. DDR2-SDRAM Interface (DBSC2)
Rev.1.00 Jan. 10, 2008 Page 549 of 1658
REJ09B0261-0100
5. The SDRAM configuration setting register (DBCONF), SDRAM timing register 0 (DBTR0),
SDRAM timing register 1 (DBTR1), and SDRAM timing register 2 (DBTR2) should be set.
6. By writing to the DDRPAD frequency setting register DBFREQ, DLL settings are made.
A. Set DLLRST = 0.
B. Set the FREQ bits to the DDRPAD frequency.
C. After setting DLLRST = 1, the software waits for the DLL stabilization time of 100
μ
s or
more required by DDRPAD.
7. Write to the DDRPAD DIC, ODT, OCD setting register DBDICODTOCD. Values to be
written should match values set in SDRAM EMRS(1).
8. Use the CMD bits in the SDRAM command control register (DBCMDCNT) to set the MCKE
signal to high level, and have the software wait for the time, requested by the respective
memory manufacturers, from cancellation of the self-refresh state until issue of a non-read
command (time tXSNR).
9. Write to DBCMDCNT to issue a REF (auto-refresh) command.
10. Set the ACEN bit in the SDRAM operation enable register (DBEN) to 1 (access enabled).
11. Set the SDRAM refresh control registers 1 and 2 (DBRFCNT1 and DBRFCNT2).
12. Set the ARFEN bit in the SDRAM refresh control register 0 (DBRFCNT0) to 1 (automatic
issue of auto-refresh enabled). Thereafter, normal access is possible.
12.5.11
Method for Securing Time Required for Initialization, Self-Refresh Cancellation,
etc.
When using DBSC2 register settings to set initialization, cancel self-refresh and the like, it is
necessary to wait a time stipulated by the SDRAM specifications. One example of this waiting is
the method used to read the DBSC2 status register (DBSTATE). Upon executing reading of the
DBSC2 status register (DBSTATE), a minimum of 8 cycles of the memory clock elapse. If
operation is at 300 MHz, then approximately 26 ns elapses in a single DBSTATE read operation.
This can be utilized to secure the required time, by repeating read access the necessary number of
times.
12.5.12
Regarding the Supported Clock Ratio
The only clock ratio supported by the DBSC2 is a ratio of 1:1 between the SuperHyway clock and
the DDR clock. Clock ratios other than 1:1 are not supported.
Содержание SH7781
Страница 4: ...Rev 1 00 Jan 10 2008 Page iv of xxx REJ09B0261 0100 ...
Страница 74: ...2 Programming Model Rev 1 00 Jan 10 2008 Page 44 of 1658 REJ09B0261 0100 ...
Страница 272: ...8 Caches Rev 1 00 Jan 10 2008 Page 242 of 1658 REJ09B0261 0100 ...
Страница 376: ...10 Interrupt Controller INTC Rev 1 00 Jan 10 2008 Page 346 of 1658 REJ09B0261 0100 ...
Страница 694: ...13 PCI Controller PCIC Rev 1 00 Jan 10 2008 Page 664 of 1658 REJ09B0261 0100 ...
Страница 762: ...14 Direct Memory Access Controller DMAC Rev 1 00 Jan 10 2008 Page 732 of 1658 REJ09B0261 0100 ...
Страница 788: ...15 Clock Pulse Generator CPG Rev 1 00 Jan 10 2008 Page 758 of 1658 REJ09B0261 0100 ...
Страница 828: ...17 Power Down Mode Rev 1 00 Jan 10 2008 Page 798 of 1658 REJ09B0261 0100 ...
Страница 846: ...18 Timer Unit TMU Rev 1 00 Jan 10 2008 Page 816 of 1658 REJ09B0261 0100 ...
Страница 1292: ...24 Multimedia Card Interface MMCIF Rev 1 00 Jan 10 2008 Page 1262 of 1658 REJ09B0261 0100 ...
Страница 1326: ...25 Audio Codec Interface HAC Rev 1 00 Jan 10 2008 Page 1296 of 1658 REJ09B0261 0100 ...
Страница 1482: ...28 General Purpose I O Ports GPIO Rev 1 00 Jan 10 2008 Page 1452 of 1658 REJ09B0261 0100 ...
Страница 1538: ...30 User Debugging Interface H UDI Rev 1 00 Jan 10 2008 Page 1508 of 1658 REJ09B0261 0100 ...
Страница 1688: ...Appendix Rev 1 00 Jan 10 2008 Page 1658 of 1658 REJ09B0261 0100 ...
Страница 1691: ......
Страница 1692: ...SH7785 Hardware Manual ...