wm9713 Wolfson Microelectronics plc, wm9713 Datasheet - Page 76

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

WM9713L
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TOUCHPANEL SETTLING TIME
For accurate touchpanel measurements, some settling time may be required between the switch
matrix applying a voltage across the touchpanel plate and the ADC sampling the signal. This time
delay function is built into the WM9713L and can be programmed as shown below.
Table 52 Touchpanel Settling Time Control (1)
Table 53 Touchpanel Settling Time Control (2)
The total time for co-ordinate or auxiliary measurements to complete is the delay time DEL, plus one
AC-Link frame (20.8µs). For a pressure measurement, the time taken is DEL plus two AC-Link
frames (41.6µs).
Although the DELAY is variable the maximum value that may be programmed depends on the
number of ADCSEL[7:1] bits set, as shown in the following table. Setting multiple ADCSEL[7:1] bits
leaves less spare AC_Link frames for the DELAY.
76h
REGISTER
ADDRESS
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
DEL
7:4
(AC-LINK FRAMES)
BIT
No delay, switch matrix always on
DELAY
128
160
192
224
256
288
16
32
48
64
96
1
2
4
8
DEL
LABEL
0000
(1 frame)
DEFAULT
1.33ms
2.67ms
3.33ms
4.67ms
5.33ms
DELAY
20.8µs
41.7µs
83.3µs
(TIME)
167µs
333µs
667µs
1ms
2ms
4ms
6ms
Touchpanel Settling Time Control
See Table 53 for details
DESCRIPTION
PP Rev 3.2 September 2008
Pre-Production
76