wm9705seft-v Wolfson Microelectronics plc, wm9705seft-v Datasheet - Page 43

• Manufacturer Part Number: wm9705seft-v
• Description: Multimedia Ac?97 Codec With Integrated Touch Screen Controller
• Manufacturer: Wolfson Microelectronics plc

WM9705
CONVERSION CONTROL
w
Table 24 Conversion Address to Channel Map
If BUSY flag is enabled (BSEN bit in reg 78h set ‘1’) then the BUSY pin will remain high until the
conversion in complete, whereby it will transition low.
This signal is output onto pin 47, EAPD/BUSY where it may be observed by the controller if
required as an interrupt. (Note that use of this BUSY flag clearly precludes use of the EAPD
external amplifier power down bit, but as the WM9705 has integrated headphone amplifier with it’s
own power down bit PR6 in register 26h, this should not be a problem. If BSEN is not set, then
EAPD operates as normal)
If SLOT method is enabled (SLEN bit in register 76h is set ‘1’) then the data is output into the
chosen slot and the appropriate slot tag bit set. Choice of which slot the data is written into is
made by setting bits SLT[2-0] in register 76h. The following table shows which slot versus [2-0]
value.
Table 25 Pen ADC Slot Select
When the conversion result has been read, then another conversion may be commenced as
required. In the event of another conversion being requested, then the stored result from the last
conversion will be overwritten when the new conversion has been completed.
However, if the WAIT bit is set in register 78h, then once a conversion is complete, the current
conversion result may not be written into the results register, until the previous conversion result
has been read. The sequence will halt at the finish of this current conversion, waiting for the
results register to be cleared. Note that this does allow the controller to slow down the rate of
conversions, so effectively determining the overall rate of conversion.
Control of ADC conversions, and screen driving functions, is by one of three methods:
•
•
•
000
001
010
011
100
101
110
111
000
001
010
011
100
101
110
Polling method
Polled Co-ordinate method
Continuous method
ADR[2-0]
SLT[2-0]
none
X- plate
Y-plate
Pressure Conversion
BMON
AUXADC
PHONE
PCBEEP
5
6
7
8
9
10
11
OUTPUT SLOT FOR
DIGITISER DATA
CHANNEL
PD Rev 4.5 July 2008
Production Data
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