Cirrus Logic EP93xx - Manual (Page 752)

25-14 DS785UM1
Copyright 2007 Cirrus Logic
Analog Touch Screen Interface
EP93xx User’s Guide
2
5
2
5
25
The register values for TSDirect can be derived from the switch positions shown in Figure 25-
8 . A “1” in the register bit position indicates that the switch is made or closed. Therefore, the
TSDirect value for battery sampling should be set to 0x4000_0700, the TSDirect value for the
measuring the DAC feedback example should be set to 0x2000_0600, and the TSDirect
value for measuring a miscellaneous input example should be set to 0x0000_0601.
To use the miscellaneous measurement input, TSDIRECT should be set to 0x0000_0601 and
the input should be on Xp pin. By using this configuration, we can measure the FULL range,
from 0 to 3.3 V. Also, to use this function we need to configure 2 items in Syscon:
• Enable the Clock for the Touch Screen (KTDIV register in Syscon)
• Set the TIN bit in DeviceCfg in Syscon. This sets the Touch Screen controller to an
inactive state.
Figure 25-8. Other Switching Diagrams
Test DAC Measure Other Misc Input
Not
Used
SW12
SW14
SW13
SW20
A/D CONVERTER
IN
REF+
REF-
VDD
SW21
SW19
SW11
SW0
SW1
SW2
SW3
SW24
SW25
SW26
SW27
100K SW23
SW22 100K
SW9
SW10
SW6
SW7
SW4
SW5
SW15
SW16
SW17
SW18
Not
Used
IN
Not
Used
SW12
SW14
SW13
SW20
A/D CONVERTER
IN
REF+
REF-
VDD
SW21
SW19
SW11
SW0
SW1
SW2
SW3
SW24
SW25
SW26
SW27
100K SW23
SW22 100K
SW9
SW10
SW6
SW7
SW4
SW5
SW15
SW16
SW17
SW18
Not
Used
SW8
VBAT
TOUCH_PRESS
SW28
SW30
DAC SW29
SW8
VBAT
TOUCH_PRESS
SW28
SW30
DAC SW29
SAMPLE VBAT
Not
Used
SW12
SW14
SW13
SW20
A/D CONVERTER
IN
REF+
REF-
VDD
SW21
SW19
SW11
SW0
SW1
SW2
SW3
SW24
SW25
SW26
SW27
100K SW23
SW22 100K
SW9
SW10
SW6
SW7
SW4
SW5
SW15
SW16
SW17
SW18
Not
Used
SW8
VBAT
TOUCH_PRESS
SW28
SW30
DAC SW29