UM10208_2
© NXP B.V. 2007. All rights reserved.
User manual
Rev. 02 — 1 June 2007
279 of 362
NXP Semiconductors
UM10208
Chapter 22: LPC2800 DDAC
4.3 Dual DAC status register (DDACSTAT - 0x8020 039C) Read Only
4.4 Dual DAC Settings Register (DDACSET - 0x8020 03A0)
Table 316. Valid combinations in the MODE and ROLLOFF fields
MODE ROLLOFF Rolloff Filter in Use
Passband
Stopband
00
00 Sharp
HB, FIR (1 or 2 fs) < 0.4535 fs > 0.5465 fs
01
01 Slow
FIR (2 fs)
< 0.2268 fs > 0.7619 fs
01
10 Sharp
FIR (2 fs)
< 0.2268 fs > 0.6094 fs
Table 317. Dual DAC status register (DDACSTAT - 0x8020 039C) Read Only
Bit(s) Name
Description
Reset
value
0
MUTED
A 1 in this field indicates that both DDAC channels are muted. This
bit is 0 while the channels are being de-muted.
0
1
PDOWN
A 1 in this field indicates that both DDAC channels are powered
down. This bit is 0 while the channels are being powered down.
0
2
RSILENT
When the ENSILDET bit in DDACCTRL is 1, this bit will be set when
the right channel detects the number of consecutive all-zero input
values indicated by the SILDET_T field in DDACCTRL. This bit is
cleared by a non-zero input value.
0
3
LSILENT
When the ENSILDET bit in DDACCTRL is 1, this bit will be set when
the left channel detects the number of consecutive all-zero input
values indicated by the SILDET_T field in DDACCTRL. This bit is
cleared by a non-zero input value.
31:4
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
Table 318. Dual DAC Settings Register (DDACSET - 0x8020 03A0)
Bit(s) Name
Description
Reset
Value
7:0
-
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-
8
RDYNPON When this bit is 1, power is applied to the right DAC.
0
9
LDYNPON When this bit is 1, power is applied to the left DAC.
0
10
LBI_DWA
When this bit is 1, the Data Weighting Algorithm (DWA) for the left
channel is bidirectional, which minimizes distortion. When this bit is 0,
the left channel DWA is unidirectional, which maximizes the
signal-to-noise ratio.
0
11
RBI_DWA
This bit selects the DWA for the right channel, as described above for
LBI_DWA.
0
12
-
Note: user software must always write a 1 to this bit.
0
31:13 -
Reserved, user software should not write ones to reserved bits. The
value read from a reserved bit is not defined.
-