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S3C2410A ADC AND TOUCH SCREEN INTERFACE
16-3
EXAMPLE FOR TOUCH SCREEN
In this example, AIN[7] is connected with XP and AIN[5]is connected with YP pad of the touch screen panel.
To control pads of the touch screen panel (XP, XM, YP and YM), four external transistors are applied and control
signals including nYPON, YMON, nXPON and XMON are connected with four external transistors.
External
Transistor
Control
Touch Panel
External Voltage Source
nYPON
YMON
nXPON
XMON
S3C2410A
XM
YP
YM
EINT[23]
EINT[22]
EINT[21]
EINT[20]
A[7]
A[5]
XP
Figure 16-2. Example of ADC and Touch Screen Interface
The following procedure is suggested:
1. Connect pads of the touch screen panel to the S3C2410A using external transistor (see Figure 16-2).
2. Select Separate X/Y Position Conversion Mode or Auto (Sequential) X/Y Position Conversion Mode to get X/Y
position.
3. Set Touch Screen Interface to Waiting Interrupt Mode,
4. If interrupt occurs, then appropriate conversion (Separate X/Y Position Conversion Mode or Auto (Sequential) X/Y
Position Conversion Mode) is activated.
5. After get the proper value of X/Y position, return to Waiting for Interrupt Mode.
NOTES
1. External voltage source should be 3.3 V.
2. Internal resistance of the external transistor should be under 5 ohm.