Circuit Operation - Olympus OEP-3 Service Manual

4-4. Circuit Operation Description of SY-282 and IF-767 Boards
Contents
. Address map

. Circuit operation

. Communication with other boards in unit
. VPR (analog video block) control
. RS communication control
Address map
Address Contents
00000h to 3ffffh 256k-byte UV-EPROM
60000h to 60003h LCD
80000h to 81fffh 16k-byte EEPROM
A0000h to A0001 SCI
C0000h Expansion port
FF710h to FFF0Fh 2k-byte SRAM
FFF10h to FFF13 Main and operation keys
FFF17h REMOTE3
FFF1Ch to FFFFFh I/O
4-4-1. Circuit Operation
Reset circuit
The reset circuit uses PST572CMT (IC190). This circuit outputs a low pulse of about 60 msec when Vcc
becomes less than 4.5 V during the power-on or off sequence. The reset pulse is input to the reset pin
(pin 63) of CPU (IC100). The CPU on the SY-282 board is then reset. After the reset is released, the
CPU outputs the reset pulses for other boards from the reset output pins (pins 59 and 60).
C100 TP
Pin 63 TP953:RESET1
Pin 59 TP594:RESET2
Pin 60 TP596:RESET
Oscillator circuit
The basic clock (9.8304 MHz) of the SY-282 board that is generated using an oscillator circuit
incorporating a crystal oscillator (X100) and CPU (IC100) can be confirmed at pin 61 [TP955 CLOCK]
of IC100. The clock and frequency-divided clock [TP951 SCI-CLK] are sent to a serial communication
circuit (IC250). The frequency-divided clock varies depending on the baud rate setting.
Baud rate [TP951 SCI-CLK]
1200 19.2 kHz
2400 38.4 kHz
4800 76.8 kHz
9600 153.6 kHz
OEP-3 V1 (UC)
IC
IC200
IC230
IC220
IC250
IC408
IC100
IC270
IC407
IC100
Object to be reset
CPU on SY board
VPR board and peripheral circuit on SY board
PRT board
CS Remarks
0 & 1
2
3
4
5
6
CPU built-in
7
7
CPU built-in
Remarks
Output of reset circuit
4-39