7-4
3. Microprocessor control circuit
3.1 Clock circuit
The X101 is crystal ;it generates an 12MHz output for microprocessor.
3.2 I
2
C buses
IC101 (pin 12) SDA
Serial data
IC101 (pin 13) SCL
Serial clock
This is I
2
C serial communication bus and is used for READ or WRITE data communication of IC101 and
IC401.
3.3 General-purpose port
3.3.1 Key scan status
IC101 pin16 is for “POWER”
IC101 pin17 is for OSD “RESET” adjust
IC101 pin18 is for OSD “SELECT” adjust
IC101 pin19 is for OSD “+” adjust
IC101 pin20 is for OSD “-” adjust
IC101 pin21 is for OSD “
4
” adjust
IC101 pin22 is for OSD “
3
” adjust
IC101 pin23 is for OSD “EXIT” adjust
3.3.2 Scaler control
IC101 pin15 (I/O) for scaler interrupt signal.
IC101 pin14 output scaler reset signal.
3.3.3 LED control
IC101 pin 2 control Q103 for Green LED lit.
IC101 pin 3 control Q102 for RED LED lit.
3.3.4 Data memory
The display control data are held by the EEPROM (IC102) ;These display control data are accessed through
the I
2
C bus of the MCU.
4. Scaler
The scaler IC (IC401) is controlled by MCU through the I
2
C bus.
IC401 embeded the ADC provide with the analog interface input.
X401 output 25MHz fed to IC401.
IC203 schmitt trigger for sync.waveform processor. And fed to IC401 for mode detect.