Production Data
WM8945
Record mode enables the entire set of Signal Enhancement functions in the ADC path. The direct
DAC path is also active, without any Signal Enhancement functions; this allows basic audio playback
and digital beep generation.
Playback mode enables the entire set of DSP functions in the DAC path. The direct ADC path is also
active, without any DSP functions; this allows basic audio record functions to the host system.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R64 (40h)
SE_CONFIG
[3:0]
DSP Configuration Mode select
0000 = Record mode
0001 = Playback mode
0010 = Reserved
3:0
0000
SE Config
Selection
0011 = Reserved
Table 12 DSP Configuration Mode Select
LOW-PASS / HIGH-PASS FILTER (LPF/HPF)
The Low-pass / High-pass filter is part of the SE1 block. This first-order filter can be configured to be
high-pass, low-pass; it can also be bypassed. The cut-off frequency is programmable; the default
setting is bypass (OFF). The filter is enabled using the SE1_LHPF_L_ENA register bit defined in
Table 13. For the derivation of the other associated registers, refer to the configuration tools supplied
with the WM8945 Evaluation Kit.
Example plots of the Low-pass / High-pass filter response are shown in Figure 14.
3
0
-3
-6
-9
-12
-15
-18
-21
-24
-27
20
39.91
79.62
158.9
317
632.5
1.262k
2.518k
5.024k
10.02k
20k
1kLPF.res Magnitude(dB)
5kHPF.res Magnitude(dB)
1kHPF.res Magnitude(dB)
200LPF.res Magnitude(dB)
5kLPF.res Magnitude(dB)
200HPF.res Magnitude(dB)
Figure 14 Low-pass / High-pass Filter Responses
PD, May 2011, Rev 4.1
33
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
