NEC LCD1501-BK Service Manual page 63

3. Microprocessor control circuit
3.1 Clock circuit
The X101 is crystal ;it generates an 12MHz output for microprocessor.
2
3.2 I C buses
IC101 (pin 12) SDA
IC101 (pin 13) SCL
2
This is I 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
2
the I C bus of the MCU.
4. Scaler
The scaler IC (IC401) is controlled by MCU through the I
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.
Serial data
Serial clock
2
C bus.
7-4