Measuring Analog Input With The Touch Screen Controls Disabled; Figure 25-7. Power Down Detect Press Switching Diagram - Cirrus Logic EP93 Series User Manual

The register values for TSDirect can be derived from the switch positions in the diagram. A
"1" in the register bit position indicates that the switch is made or closed. When
TSSetup.S28EN is low, the TSDirect value for 4- or 8-wire touch press detection should be
set to 0x0040_4601. Otherwise, when TSSetup.S28EN is high, the TSDetect value should be
0x1040_4601. And, when TSSetup.S28EN is low, the TSDirect value for 5-wire touch press
detection should be set to 0x0042_0601. Otherwise, when TSSetup.S28EN is high, the
TSDirect value should be 0x1042_0601.
4/8 wire detect Press
SW28
100K
SW22
100K
SW23
SW19
SW11
SW20
SW13
SW21
SW0
X+
SW1
X-
Y+ SW2
Y-
SW3
SW12
SW14
SW4
SW5
SW6
SW7
SW24
SW25
SW26
SW27
SW15
SW16
SW17
SW18

Figure 25-7. Power Down Detect Press Switching Diagram

25.2.4 Measuring Analog Input with the Touch Screen Controls Disabled

The analog switch array can be used to measure the chip battery voltage, Digital to Analog
Converter feedback, or other miscellaneous analog inputs when the touch screen controller is
disabled. Figure 25-8
extra reference lines that are not used for 4-wire or 5-wire touch screens can be read from
the APB bus by temporarily disabling the touch screen controller. Please note that the initial
read should be viewed as a convert command where the data provided is stale and should be
discarded.
DS785UM1
TOUCH_PRESS
SW29
DAC
VDD
VBAT
SW8
SW30
A/D CONVERTER
IN
SW9
REF+
REF-
SW10
shows the switch configuration for reading these values. Note that any
Copyright 2007 Cirrus Logic
Analog Touch Screen Interface
5 wire detect Press
TOUCH_PRESS
SW28
VDD
100K
SW22
100K
SW23
SW19
SW11
SW20
SW13
SW21
SW0
V+
SW1
V-
SW2
Z+/-
SW3
Z-/+
SW12
SW14
SW4
SW5
SW6
SW7
SW24
Not used
SW25
Not used
SW26
Wiper
SW27
Not used
SW15
SW16
SW17
SW18
EP93xx User's Guide
25
SW29
DAC
VBAT
SW8
SW30
A/D CONVERTER
IN
SW9
REF+
REF-
SW10
25-13