Samsung SCX-1100, Service Manual

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3-38
CIRCUIT DESCRIPTION
Samsung Electronics
Repair Manual
3-10 I/O PORT configuration and use usage
It has 32 I/O Ports, and 24 Ports of them are arranged to decide I/O direction with Software Control, and the rest 8 Ports are
arranged to be used for Input or Output only. All of I/O Ports are classified into four Blocks according to the characteristics of
I/O Control, and each Block consists of 8 Ports.
1) Assignment of Port PAX
-. PA0 : LCD VCC CONTROL SIGNAL (POWER ON/OFF)
-. PA1 : LED 1
-. PA2 : RESERVED
-. PA3 : RESERVED
-. PA4 : RESERVED
-. PA5 : RESERVED
-. PA6 : RESERVED
-. PA7 : RESERVED
2) Assignment of port PBX
-. PB0(Output) : LCD Enable
-. PB1(Output) : LCD R/W
-. PB2(Output) : LCD RS
-. PB3(Input) : GND
-. PB4(Input) : Unused (Pull-up)
-. PB5(Input) : GND
-. PB6(Output) : UART TXD in Main UART
-. PB7(Input) : UART RXD from Main UART
LCD ON/OFF
In case of VCC applied to LCD No. 3 PIN (BACKGROUND LEVEL), all the LCD screen will be erased. When the power is
applied, MICOM PA0~7 are Default High LEVEL, so LCD will be OFF. From Jupiter3, LCD will be ON simultaneously with OPE
reset.
Q1, Q2 have the function of simply doing On/off only.
When pressing the Power Key, actual power is not turned Off but 11.75V terminal of Thundervolt Off in the Main, while simply
the LCD DISPLAY should not appear in OPE. At this point, Micom should be operated normally to recognize the Key when
pressing the Power key again. [The same effect as Power save]
Type I/O Control I/O direction USE Remarks
PA X Byte Control I/O => Output LED Control Used as LCD VCCCONTROL in SCX-1100.
PB X Byte Control In : 4, Out : 4 UART, LCD, Sensor SCX-1100 SENSOR not applied.
PC X Byte Control I/O => Input Key Input
PD X Byte Control I/O => Output LCD Data, Key Scan