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NUC970 Technical Reference Manual
Publication Release Date: Dec. 15, 2015
- 920 -
Revision V1.30
NUC97
0
T
E
CHNIC
A
L
RE
F
E
RE
N
CE
MA
NUA
L
SD Host Control and Status Register (SDH_CTL)
Register
Offset
R/W
Description
Reset Value
SDH_CTL
0x820
R/W
SD Host Control and Status Register
0x0101_0000
31
30
29
28
27
26
25
24
CLK_KEEP1
SDPORT
Reserved
SDNWR
23
22
21
20
19
18
17
16
BLK_CNT
15
14
13
12
11
10
9
8
DBW
SW_RST
CMD_CODE
7
6
5
4
3
2
1
0
CLK_KEEP0
CLK8_OE
CLK74_OE
R2_EN
DO_EN
DI_EN
RI_EN
CO_EN
Bits
Description
[31]
CLK_KEEP1
SD Host Port 1 Clock Keep Running Enable
0 = SD host port 1 clock generation controlled by SD host automatically.
1 = SD host port 1 clock always keeps free running.
[30:29]
SDPORT
SD Port Selection
00 = SD host port 0 is selected.
01 = SD host port 1 is selected.
10 = Reserved.
11 = Reserved.
[28]
Reserved
Reserved.
[27:24]
SDNWR
NWR Parameter for Block Write Operation
This value indicates the NWR parameter for data block write operation in SD clock counts.
The actual clock cycle will be SDNWR+1.
[23:16]
BLK_CNT
Block Counts to Be Transferred or Received
This field contains the block counts for data-in and data-out transfer. For
READ_MULTIPLE_BLOCK and WRITE_MULTIPLE_BLOCK command, software can use
this function to accelerate data transfer and improve performance. Don't fill 0x0 to this field.
Note:
For READ_MULTIPLE_BLOCK and WRITE_MULTIPLE_BLOCK command, the
actual total length is BLK_CNT * (BLKLEN (SDH_BLEN[10:0]) +1).
[15]
DBW
SD Data Bus Width (for 1-bit / 4-bit Selection)
0 = Data bus width is 1-bit.
1 = Data bus width is 4-bit.
[14]
SW_RST
Software Engine Reset
0 = Writing 0 to this bit has no effect.
1 = Writing 1 to this bit will reset the internal state machine and counters. The contents of
control register will not be cleared (but RI_EN (SDH_CTL[1]), DI_EN (SDH_CTL[2]), DO_EN
(SDH_CTL[3]) and R2_EN (SDH_CTL[4]) will be cleared). This bit will be auto cleared after
few clock cycles.