Plug Presence Detect - Cirrus Logic CS42L42 Manual

• If HSDET_CTRL = 10 or 11, the SW_x_y bits do not affect the state of the internal switches.
These settings are stored in the VP power domain, so that the switches remain correctly configured, even if the VCP, VL,
VA, or VD_FILT supplies are powered off. The HSDET logic and status bits are stored in the VD_FILT power domain.
To prevent audible pop/clicks in the HPs, it may be desirable in some applications to precharge the HSBIAS and HSBIAS_
FILT capacitors before setting the switches to their final values. Set SW_HSB_HS3/4 and SW_HSB_FILT_HS3/4 to
minimize transients at the HPs associated with charging capacitors. After the capacitors are charged, the switches can be
changed to their desired states.
Note that headset S0 button-detect features are not available until internal switches have been configured. Also,
depending on the headset type detected, switch settings, and board connections, it may be necessary to set
(see p. 153) to have the proper signal polarity.
HSDET_TYPE
Pin 1
1 Left audio
2 Left audio
3 Left audio
4
1.After performing an automatic headset-detection sequence, the output of the headset comparators may not be valid even if switch configurations
are correct for a given plugged-in headset type.
Table 4-23. Headset Type Detect—Switch States after Autodetection (0 = Switch Open; 1 = Switch Closed)
HSDET_TYPE
HS3
1 1
2 0
3 1
4 1

4.14 Plug Presence Detect

The CS42L42 uses TIP_SENSE and RING_SENSE to detect plug presence. The sense pins are debounced to filter out
brief events before being reported to the corresponding presence-detect bit and generating an interrupt if appropriate.
4.14.1 Plug Types
The plug-sense scheme supports the following plug types:
• Tip–Ring–Sleeve (TRS)—Consists of a segmented metal barrel with the tip connector used for HPOUTA, a ring
connector used for HPOUTB, and a sleeve connector used for HSGND.
DS1083F2
Section 5
Start State
HSDET_
TYPE 1
Switch
States
Collect Comparator
State Data 2
(H or L)
Type
L then L
HSDET_
3
TYPE 2
Switch
States
Type
L then H
2
Figure 4-44. Automatic Headset Detect Flowchart
Table 4-22. Automatic Headset Detect Decode
Headset Plug
Pin 2 Pin 3 Pin 4
Right audio GND MIC
Right audio MIC GND
Right audio GND GND
Optical
REF_
HS4 HS3
0 1
1 0
1 1
0 1
provides a recommended headset-type detection sequence.
Note: Flow can be automatic, as
shown here, or stepped through
Collect
in any fashion via a manual -
Comparator
override mode to accommodate
State Data 1
unforeseen headsets
(H or L)
Type
H then L
1
Type
H then H
4
DC Test Comparator Results
HSDET_TYPE 1 Switch State
High
Low
Low
High
SW_
HSB_FILT_
HS4 HS3
0 0
1 1
1 0
0 0
4.14 Plug Presence Detect
Report state
to control port
so processor can
ask user for
headset definition
1
HSDET_TYPE 2 Switch State
Low
High
Low
High
HSB_ GNDHS_
HS4 HS3
1 1
0 0
0 1
1 1
CS42L42
ADC_INV
HS4
0
1
1
0
79