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ADC AND TOUCH SCREEN INTERFACE S3C2410A
16-4
FUNCTION DESCRIPTIONS
A/D Conversion Time
When the PCLK frequency is 50 MHz and the prescaler value is 49, total 10-bit conversion time is given:
A/D converter freq. = 50 MHz/(49+1) = 1 MHz
Conversion time = 1/(1 MHz / 5cycles) = 1/200 kHz = 5 us
NOTE
This A/D converter is designed to operate at maximum 2.5 MHz clock, so the conversion rate can go up to
500 KSPS.
Touch Screen Interface Mode
1. Normal Conversion Mode
Normal Conversion Mode (AUTO_PST = 0, XY_PST = 0) is generally used for General Purpose ADC Conversion.
This mode can be initialized by setting the ADCCON and ADCTSC and completed with a read the XPDATA
(Normal ADC) value of ADCDAT0 (ADC Data Register 0).
2. Separate X/Y Position Conversion Mode
Separate X/Y Position Conversion Mode is consist of two Conversion Modes: X-Position Mode and Y-Position
Mode.
The first mode is operated in the following way:
X-Position Mode (AUTO_PST = 0 and XY_PST = 1) writes X-position conversion data to XPDATA of ADCDAT0
register. After conversion, The Touch Screen Interface generates the Interrupt source (INT_ADC) to Interrupt
Controller.
Y-Position Mode (AUTO_PST = 0 and XY_PST = 2) writes Y-position conversion data to YPDATA of ADCDAT1.
After the conversion, the Touch Screen Interface also generates the Interrupt source (INT_ADC) to Interrupt
Controller.
Table 16-1. Condition of Touch Screen Panel Pads in Separate X/Y Position Conversion Mode
XP XM YP YM
X Position Conversion External Voltage GND AIN[5] Hi-Z
Y Position Conversion AIN[7] Hi-Z External Voltage GND