Function Descriptions - Samsung S3C2416 User Manual

S3C2416X RISC MICROPROCESSOR

2.2 FUNCTION DESCRIPTIONS

2.2.1 A/D Conversion Time
When the PCLK frequency is 50 MHz, the prescaler value is 49 and total 10-bit and 12-bit conversion time is
given:
A/D converter freq. = 50 MHz/(49+1) = 1 MHz
Conversion time = 1/(1MHz / (5cycles)) = 1/200 KHz = 5 us
This A/D converter is designed to operate at maximum 5 MHz clock, so the conversion rate can go up to
1MSPS.
2.2.2 Touch Screen Interface Modes (AIN6 ~ AIN9)
1. Normal conversion mode (AUTO_PST = 0, XY_PST = 0)
The operation of this mode is identical with AIN0~AIN5's. It can be initialized by setting the ADC Control
Register (ADCCON) and ADC touch screen control register (ADCTSC). All of the switches and pull-up
resister should be turned off (reset value 0x58 makes switches turn-off). The converted data can be read out
from ADC conversion data 0 register (ADCDAT0).
2. Separate X/Y position conversion mode (AUTO_PST = 0, XY_PST : contorl)
This mode consists of two states; one is X-position measurement state and the other is Y-position
measurement state.
X-position measurement state is operated as the following way; set XY_PST is '1' and read out the converted
data (X-position) from ADCDAT0. The end of X-position conversion can be notified by interrupt (INT_ADC).
Y-position measurement state is operated as the following way; set XY_PST is '2' and read out the converted
data (Y-position) from ADCDAT1. The end of Y-position conversion can be notified by interrupt (INT_ADC).
State
X-position measurement
Y-position measurement
3. Auto(Sequential) X/Y position conversion mode (AUTO_PST = 1, XY_PST = 0)
Auto (sequential) X/Y position conversion mode is operated as the following. Touch screen controller
sequentially converts X-position and Y-position that is touched. After touch screen controller converts X-
position data to ADCDAT0 and then converts Y-position data to ADCDAT1, Touch screen interface generates
interrupt (INT_ADC). The measurement states are automatically changed.
NOTE
XP
VDDA_ADC VSSA_ADC
AIN9
ADC AND TOUCH SCREEN INTERFACE
XM YP
AIN7
Hi-z VDDA_ADC
YM
Hi-z
VSSA_ADC
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