12. DDR2-SDRAM Interface (DBSC2)
Rev.1.00 Jan. 10, 2008 Page 504 of 1658
REJ09B0261-0100
12.4.11
SDRAM Refresh Status Register (DBRFSTS)
The SDRAM refresh status register (DBRFSTS) is a readable/writable register. It is initialized
only upon power-on reset.
16
17
18
19
20
21
22
23
24
25
26
27
28
29
31
30
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIt:
Initial value:
R/W:
0
1
2
3
4
5
6
7
8
9
10
11
12
13
15
14
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RFUDF
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
R/W
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIt:
Initial value:
R/W:
Bit Bit
Name
Initial
Value R/W
Description
31 to 1
⎯
All 0
R
Reserved
These bits are always read as 0. The write value should
always be 0.
Operation when a value other than 0 is written is not
guaranteed.
0
RFUDF
0
R/W
Refresh Counter Underflow Bit
Set to 1 to indicate that the refresh counter has
underflows when the refresh counter changes from 1 to
0. This bit is cleared to 0 by writing 0 to it.
Underflow may occur because the LV0TH bit value is
smaller than the maximum number of command
execution cycles, so that refresh cannot be issued until
the counter value reaches 0. In this case, the value of
the LV0TH bit should be changed.
For details on the refresh counter, refer to section
12.5.5, Auto-Refresh Operation.
0: Indicates that no underflow occurs.
1: Indicates that an underflow occurs.
Содержание SH7781
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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 ...
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