WM8948 Datasheet, PDF (35/189 Pages) Wolfson Microelectronics plc – Stereo Low-Power CODEC with Video Buffer and Touch Panel Controller

Production Data
WM8948
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
R64 (40h)
SE Config
Selection
BIT
LABEL
3:0 SE_CONFIG
[3:0]
Table 12 DSP Configuration Mode Select
DEFAULT
DESCRIPTION
0000
DSP Configuration Mode select
0000 = Record mode
0001 = Playback mode
0010 = Reserved
0011 = Reserved
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 or low-pass; it can also be bypassed. The cut-off frequency is programmable; the default
setting is bypass (OFF). The left and right channel parameters may be programmed individually. The
left and right filters are enabled using the SE1_LHPF_L_ENA and SE1_LHPF_R_ENA register bits
defined in Table 13. For the derivation of the other associated registers, refer to the configuration
tools supplied with the WM8948 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)
Figure 14 Low-pass / High-pass Filter Responses
5kLPF.res Magnitude(dB)
200HPF.res Magnitude(dB)
w
PD, May 2011, Rev 4.1
35