WM9705_06 WOLFSON [Wolfson Microelectronics plc], WM9705_06 Datasheet - Page 41

• Manufacturer Part Number: WM9705_06
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

Reg Name
76h
78h
7Ah
WM9705
TIMING OF PEN DIGITISER OPERATIONS
CONTROL OF PEN DIGITISER FUNCTIONS
w
Digitizer control
Digitizer control
Pen Digitizer data
POLL
ADR[2-0]
COO
CTC
CR[1-0]
DEL[3-0]
SLEN
SLT[2-0]
BIT
PNDN ADR2 ADR1 ADR0 D11
POLL ADR2 ADR1 ADR0 COO
PRP1 PRP0 RPR PDEN PINV BSEN BINV WAIT
D15
15
14-12
11
10
9,8
7-4
3
2-0
LOCATION
D14
Timing of pen digitiser operations is linked to the AC link frame timing. A single ADC conversion
takes one frame to complete, including taking a sample, converting it, and passing it into the
register ready to be read back. This therefore allows a maximum conversion rate of 48ks/s, but in
practise to allow time for screen plates to settle etc, much lower rates of conversion are
anticipated.
The ADC is powered up only for the duration of each conversion, therefore power consumption is
a linear function of the conversion rate chosen.
Control of the digitiser functions is via control bits written into control registers via the AC link. The
following table shows the name, function and location of the control bits for the pen digitser
section of the WM9705. Address locations are chosen to avoid unexpected corruption of normal
AC’97 audio codec operation, using mostly vendor specific addresses from the AC’97 adddress
map.
INDEX 76H – DIGITISER CONTROL WORD 1 – READ/WRITE REGISTER
D13
D12
Starts a single polled conversion (resets itself at completion)
Sets the address of the single conversion in polled mode, or extra conversions in Co-
ordinate or Continuous mode. See Table 24.
Selects a co-ordinate set of conversions
Starts continuous conversion operation
Sets continuous conversion rate
Sets the delay between screen being driven and X or Y sample being taken
Slot enable bit; allows conversion results to be output onto chosen slot
Slot select bits; choose which slot to output data results in
D11
D10
CTC
D10
CR1
D9
D9
CR0 DEL3 DEL2 DEL1 DEL0 SLEN SLT2 SLT1
D8
D8
D7
PIL
D7
FUNCTION
PHIZ MSK1 MSK0 PDD3 PDD2 PDD1 PDD0
D6
D6
D5
D5
D4
D4
D3
D3
PD Rev 4.4 August 2006
D2
D2
D1
D1
Production Data
SLT0
D0
D0
Default
0006h
0000h
0000h
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