參數(shù)資料
型號(hào)： WM9712LEFL
廠商： Wolfson Microelectronics
元件分類： Codec
英文描述： AC97 Audio and Touchpanel CODEC
中文描述： AC97音頻編解碼器和觸摸屏
文件頁數(shù)： 40/78頁
文件大?。?/td> 689K
代理商： WM9712LEFL
WM9712L
Production Data
w
PD Rev 4.0 December 2003
40
When the touchpanel is not being touched, no current flows in the circuit, and the PENDOWN signal
is low. When the panel is touched with a pen or finger, current flows through R
PU
and the panel, and
the comparator output goes high.
The PENDOWN signal can be read from bit 15 in register 7Ah (labeled PNDN). It can also be
observed on pin 46 (GPIO3 / PENDOWN), if the pin is not used for GPIO (GE3=0). Additionally,
PENDOWN is passed to the GPIO logic block (register 54h, bit 13), where it can generate CPU
interrupts, and / or to wake up the WM9712L from sleep mode (see “GPIO and Interrupt Control”
section).
I
P
Y+ (15)
X+
(14)
Y- (17)
X- (16)
R
X+
R
Y-
pen / finger
R
Y+
R
X-
TPGND
WM9712
TPVDD
ADC
V
- V
= I
R
= proportional to contact resistance
Figure 9 Touch Pressure Measurement on 4-wire Touchpanel
Touch pressure can be determined indirectly by measuring the contact resistance R
C
between the
top and bottom plates. R
C
decreases as the touch pressure on the panel increases. The WM9712L
measures R
C
by sending a constant current I
P
through the touchpanel and measuring the potential
on each plate. The two values are subtracted in the digital domain to obtain the potential difference,
which is proportional to R
C
.
To suit different types of touchpanels, the magnitude of I
P
can be set to either 400
μ
A or 200
μ
A using
the PIL control bit.
PRINCIPLE OF OPERATION - FIVE-WIRE TOUCHPANEL
Five-wire touchpanels are connected to the WM9712Las follows:
Top sheet contact = WIPER/AUX4 (pin 12)
Top left corner of bottom sheet = TL (pin 16)
Top right corner of bottom sheet = TR (pin 15)
Bottom left corner of bottom sheet = BL (pin 17)
Bottom right corner of bottom sheet = BR (pin 14)
V
M
= proportional to X position
WM9712
WIPER (12)
TR (15)
ADC
V
REF+
V
REF-
VM
TPGND
TPGND
TPVDD
TPVDD
BR (14)
BL (17)
TL (16)
Figure 10 X Co-ordinate Measurement on 5-wire Touchpanel
相關(guān)PDF資料
PDF描述
WM9712LEFT AC97 Audio and Touchpanel CODEC
WM9712LEFV AC97 Audio and Touchpanel CODEC
WM9712LSEFL AC97 Audio and Touchpanel CODEC
WM9712LSEFT AC97 Audio and Touchpanel CODEC
WM9712LSEFV AC97 Audio and Touchpanel CODEC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
WM9712LEFL/RV 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
WM9712LEFL/V 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
WM9712LEFT 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
WM9712LEFT/RV 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
WM9712LEFV 制造商:WOLFSON 制造商全稱:WOLFSON 功能描述:AC97 Audio and Touchpanel CODEC
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