WM9713L_06 WOLFSON [Wolfson Microelectronics plc], WM9713L_06 Datasheet - Page 71

• Manufacturer Part Number: WM9713L_06
• Description: AC 97 Audio + Touchpanel CODEC
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

Pre-Production
ADDITIONAL FEATURES
AUXILIARY ADC INPUTS
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The ADC used for touchpanel digitisation can also be used for the sole purpose of auxiliary
measurements, provided that it is enabled (register 78h, PRP = 11). The WM9713L has three pins
that can be used as auxiliary ADC inputs:
Additionally, the speaker supply (SPKVDD) can be used as an auxillary ADC input through an on-
chip potential divider giving an input to the auxillary ADC of SPKVDD/3. This input is referred to as
the AUX3 input (see Figure 16).
Note that pin 12 connects to the wiper of a 5-wire touchpanel wiper function. Auxiliary measurements
taken on pin 12 are only meaningful when it is not connected to a touchpanel (i.e. a 4-wire
touchpanel, or no touchpanel at all, is used). Pins 29 and 30 are also used as comparator inputs (see
Battery Alarm and Battery Measurement), but auxiliary measurements can still be taken on these
pins at any time. The ADCSEL control bits select between different ADC inputs, as shown in Table
57.
The ADCSEL control bits determine which type of measurement is performed (see below). When
performing auxiliary conversions the co-ordinate mode bit, COO, should be off (0).
If CTC=0 then only one of the ADCSEL[7:1] bits should be set. If operating in continuous mode
(CTC=1), then more than one ADCSEL[7:1] bit may be set, and conversions will be performed
cyclically in the following order => “AUX1,AUX2,AUX3,AUX4…” – dependent on which bits are set.
Table 57 Auxiliary ADC Measurements
Auxiliary ADC measurements are initiated in the same way as touchpanel measurements, and the
data is returned in the same manner. Please refer to the “Controlling the Touchpanel Interface”
section.
74h
REGISTER
ADDRESS
MIC2A / COMP1 / AUX1 (pin 29)
MIC2B / COMP2 / AUX2 (pin 30)
WIPER / AUX4 (pin 12)
BIT
7
6
5
4
0
ADCSEL_AUX4
ADCSEL_AUX3
ADCSEL_AUX2
ADCSEL_AUX1
COO
LABEL
DEFAULT
0
0
0
0
0
Enable AUX4 measurement (pin12)
Enable AUX3 measurement (SPKVDD)
Enable AUX2 measurement (pin30)
Enable AUX1 measurement (pin29)
Enable co-ordinate mode – for touchpanel
conversions only (see “Controlling the
Touchpanel Interface”)
DESCRIPTION
PP Rev 3.0 June 2006
WM9713L
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