wm9712l Wolfson Microelectronics plc, wm9712l Datasheet - Page 45

• Manufacturer Part Number: wm9712l
• Description: Ac?97 Audio And Touchpanel Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
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If the SLEN bit is set to ‘1’, then the touchpanel data appears on the AC-Link slot selected by the
SLT control bits, as shown below. The Slot 0 ‘tag’ bit corresponding to the selected time slot is
asserted whenever there is new data on that slot.
Table 30 Returning Touchpanel Data Through an AC-Link Time Slot
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 WM9712L and can be programmed as shown below.
Table 31 Touchpanel Settling Time Control (1)
Table 32 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).
76h
76h
REGISTER
ADDRESS
REGISTER
ADDRESS
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
DEL
7:4
(AC-LINK FRAMES)
3
2:0
BIT
BIT
No delay, switch matrix always on
DELAY
128
160
192
224
256
288
16
32
48
64
96
SLEN
SLT
1
2
4
8
LABEL
DEL
LABEL
0
110
DEFAULT
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
Slot Readback Enable
0: Disabled (readback through register only)
1: Enable (readback slot selected by SLT)
AC’97 Slot Selection for Touchpanel Data
000: Slot 5
001: Slot 6
…
101: Slot 10
110: Slot 11
111: RESERVED
Touchpanel ADC Settling Time
DESCRIPTION
DESCRIPTION
PD Rev 4.5 August 2006
WM9712L
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