Owner manual

VmodTFT Reference Manual
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Touch
Corner
X Reading Y Reading
Top Left 096h 12Ch
Top Right F6Eh 12Ch
Bottom Left 096h ED8h
Bottom Right F6Eh ED8h
Table 4 Actual 12-Bit Voltage Readings
Using these experimental values, the touch
coordinates scaled to the LCD active area can
be easily determined. Use the following
equations, where V
x
and V
y
are the voltage
readings for the X and Y plates.
Equation 1 Convert Voltage Readings to
Coordinates
Touch can be detected on the PENIRQ
interrupt signal. A low value indicates the
screen is being touched.
You can also measure the pressure of the
touch, referred to as the Z coordinate. The
measurement requires a different biasing of
the touchscreen and requires some
calculation. The equation uses the X and Y
plate resistance, which for this panel can be
approximated by 1024 and 256 ohms,
respectively.
For information on how to use the touch
controller to measure touch pressure, refer to
the AD7873 datasheet at
http://www.analog.com/static/imported-
files/data_sheets/AD7873.pdf
VHDCI Connector
The VmodTFT is only compatible with system
boards using 3.3V-level signaling and should
only be attached to the system board once the
signals driven by the system board are
defined.
VHDCI VmodTFT VHDCI VmodTFT
IO1-P TP_BUSY IO1-N NC
IO2-P TP_DIN IO2-N TP_DOUT
IO3-P TP_CS IO3-N TP_PENIRQ
IO4-P TFT_B[5] IO4-N TFT_B[7]
IO5-P TFT_B[4] IO5-N TFT_B[6]
IO6-P TFT_B[2] IO6-N TFT_B[3]
IO7-P TFT_B[0] IO7-N TFT_B[1]
IO8-P TFT_G[6] IO8-N TFT_G[7]
IO9-P TFT_G[5] IO9-N TFT_G[4]
IO10-P TP_DCLK IO10-N NC
IO11-P TFT_CLK IO11-N NC
IO12-P TFT_G[1] IO12-N TFT_G[3]
IO13-P TFT_G[0] IO13-N TFT_G[2]
IO14-P TFT_R[6] IO14-N TFT_R[7]
IO15-P TFT_R[4] IO15-N TFT_R[5]
IO16-P TFT_R[2] IO16-N TFT_R[3]
IO17-P TFT_R[1] IO17-N TFT_R[0]
IO18-P TFT_DISP IO18-N TFT_DE
IO19-P TFT_EN IO19-N LED_EN
IO20-P NC IO20-N NC
Table 5 VHDCI Connector Pin-Out
Camera Output Camera Input