Samsung S5PC100 User Manual page 1734

S5PC100 USER'S MANUAL (REV1.0)
4 FUNCTION DESCRIPTIONS
A/D Conversion Time
If the PCLK frequency is 66MHz and the prescaler value is 65, total 10-bit or 12-bit conversion time is as follows.
A/D converter freq. = 66MHz/(65+1) = 1MHz
Conversion time = 1/(1MHz / 5cycles) = 1/200kHz = 5 us
NOTE: This A/D converter was designed to operate at maximum 5MHz clock, therefore the conversion rate can go up to
1MSPS.
Touch Screen Interface Mode
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 ADCCON (ADC
Control Register) and ADCTSC (ADC touch screen control register). 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
ADCDAT0 (ADC conversion data 0 register).
2. Separate X/Y position conversion Mode (AUTO_PST = 0, XY_PST:control)
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 '2b'01' and read out the
converted data (X-position) from ADCDAT0. When XY_PST is '1', XP and XM switch is automatically on and
ADC channel selection bits are automatically changed to '5'. 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. When XY_PST is '2', YP and YM switch is automatically on and ADC
channel selection bits are automatically changed to '7'. 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 in the following method: Touch screen controller
sequentially converts X-Position and Y-Position that is touched. After Touch screen controller writes X-
measurement data to ADCDAT0 and writes Y-measurement data to ADCDAT1, Touch screen interface
generates Interrupt (INT_ADC). The measurement states are automatically changed. When X-Position is
detected, XP and XM switch is automatically on and ADC channel selection bits are automatically changed
to '5'. And then when X-Position is detected, YP and YM switch is automatically on and ADC channel
selection bits are automatically changed to '7'. After Auto X/Y position conversion, mode is changed for pull-
up interrupt detection (ADCTSC = 0x173)
.
XP
VDDA_ADC VSSA_ADC
AIN9
ADC AND TOUCH SCREEN INTERFACE
XM YP
AIN7
Hi-z VDDA_ADC
YM
Hi-z
VSSA_ADC
10.7-3