wm9713 Wolfson Microelectronics plc, wm9713 Datasheet - Page 70

• Manufacturer Part Number: wm9713
• Description: Ac?97 Audio + Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

WM9713L
CONTROLLING THE TOUCHPANEL DIGITISER
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All touchpanel functions are accessed and controlled through the AC-Link interface.
PHYSICAL CHARACTERISTICS
The physical characteristics of the touchpanel interface are controlled through register 78h, as shown
below.
Table 46 Touchpanel Digitiser Control (Physical Characteristics)
POWER MANAGEMENT
To save power, the touchpanel digitiser and the pen-down detector can be independently disabled
when they are not used. The power consumption of the pen-down detector is normally negligible,
except when the pen is down.
The pen ADC is powered-down using PADCPD, register 3Ch bit 15.
The state of the digitiser and pen down detector is controlled by the following bits.
Table 47 Touchpanel Digitiser Control (Power Management)
78h
3Ch
78h
REGISTER
REGISTER
ADDRESS
ADDRESS
12
8
0:5
15
15:14
13
BIT
BIT
45W
PIL
RPU
LABEL
PADCPD
PRP
RPR
LABEL
0 (4-wire)
0 (200µA)
000001
(64kΩ)
DEFAULT
1 = off
00
0
DEFAULT
Touchpanel Type Control
0 = 4-wire
1 = 5-wire
Pressure Measurement Current Control
0 = I
1 = I
Internal Pull-up Resistor Control
000000 = Reserved
000001 = 64kΩ/1 (most sensitive)
000010 = 64kΩ/2
000011 = 64kΩ/3
… (64kΩ/binary value of RPU)
111111 = 64kΩ/63 (least sensitive)
Note: used to adjust sensitivity of Pen Down
detection
Touchpanel / AUXADC Disable Control
1 = Disabled
0 = Enabled
Touchpanel Digitiser Power State
Control
00 = Pen digitiser off, pen detect off, no
wake-up on pen down (default)
01 = Pen digitiser powered off, pen detect
enabled, touchpanel digitiser wakes up
(changes to state 11) on pen-down
10 = Pen digitiser off, pen detect enabled,
no wake-up on pen down
11 = Pen digitiser and pen detect enabled
Pen Detect Wake-up Mode Control
0 = Wake-up the AC-Link only (hold
SDATAIN high until controller sends warm
reset or cold reset)
1 = Wake-up the WM9713L without
waiting for a reset signal from the
controller
P
P
= 200µA
= 400µA
DESCRIPTION
DESCRIPTION
PP Rev 3.2 September 2008
Pre-Production
70