![Samsung S3C2451X Скачать руководство пользователя страница 644](http://html.mh-extra.com/html/samsung/s3c2451x/s3c2451x_user-manual_340826644.webp)
Preliminary
ADC AND TOUCH SCREEN INTERFACE
S3C2451X RISC MICROPROCESSOR
24-4
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
4. Waiting for interrupt mode (ADCTSC = 0xd3)
Touch screen controller generates interrupt (INT_TC) signal when the stylus is down. The value of ADC touch
screen control register (ADCTSC) is ‘0xd3’; PULL_UP is ‘0’, XP_SEN is ‘1’, XM_SEN is ‘0’, YP_SEN is ‘1’ and
YM_SEN is ‘1’. Touch interrupt can be generated when stylus pen is down or up.
After touch screen controller generates interrupt signal (INT_TC), waiting for interrupt mode must be cleared.
(XY_PST sets to the No operation Mode)
Mode XP
XM
YP
YM
Waiting for Interrupt Mode VDDA_ADC(Pull-up enable)
Hi-z
Hi-z
VSSA_ADC
Standby Mode
Standby mode is activated when ADCCON [2] is set to '1'. In this mode, A/D conversion operation is halted and
ADCDAT0, ADCDAT1 register contains the previous converted data.
Programming Notes
1. The A/D converted data can be accessed by means of interrupt or polling method. With interrupt method,
the overall conversion time - from A/D converter start to converted data read - may be delayed because of
the return time of interrupt service routine and data access time. With polling method, by checking the
ADCCON[15] - end of conversion flag-bit, the read time from ADCDAT register can be determined.
2. A/D conversion can be activated in different way: After ADCCON[1] - A/D conversion start-by-read
mode-is set to 1, A/D conversion starts simultaneously whenever converted data is read.
Stylus Down
X-Conversion
Y-Conversion
Stylus Up
A
B
C
= x (1/X-tal clock) or x (1/EXTCLK clock)
= x (1/PCLK clock) + 5 x (1/PCLK clock) x (1)
= x (1/PCLK clock) + 5 x (1/PCLK clock) x (1)
= Delay value of ADCDLY register
XP
YP
Figure 24-2. Timing Diagram in Auto (Sequential) X/Y Position Conversion Mode