Fukuda Denshi DS-8400, Service Manual

Page: 76 / 274

4-2
Main Unit (DSC-8400)
The diagram below explains the block diagram of the DSC-8400 and its function.
Circuit Description of Main CPU Board (PCB-7673)
The Main CPU Board controls, displays, and records the monitor. The input signal operation of the touch
panel, remote control, etc are processed by the CPU and then the display of the monitor or each measurement
condition will change.
MAIN CPU
SH7763 (RENESAS, internal clock 266MHz RISC processor) is used as the CPU. This CPU controls
memories such as DRAM, each peripheral IC, and sound source, displays the waveform, numeric data, and
menu, and processes manipulated input signals from the Touch Panel/Remote Control Unit. The inside CPU
includes DMAC (Direct Memory Access), Timer, and SCI (Serial Communication Interface).
Flash Memory
The flash memory has a capacity of 64 MByte and the program is saved in this Flash Memory. And using
Flash Memory, the program can be easily upgraded.
SDRAM
SDRAM has a capacity of 128MByte, conducts backup operation for approximately 5 minutes, and backs up
the recall and short trend data. Also, the program stored in the flash memory is loaded in the SDRAM and
executed after starting.
SRAM
The SRAM has a capacity of 2MByte performing storage of the monitor setup. Backup for 6 years is possible
using a lithium battery.
EEPROM
EEPROM stores equipment-specific information such as serial number, MAC address, and operation time of
system and components.
Monitoring WDT and Power Supply
WDT/ Monitoring Power Supply will reset the system when the program functions abnormally or a power
voltage reduction of CPU is detected. The WDT function is disposed in the system control CPLD in this board.
A/D converter
The CPU built-in A/D converter always monitors each power voltage on the board, board temperature, each
status of the recorder unit.
System control CPLD
It includes generation of control signals for CS of peripheral devices and WR etc. generation of reset signals
for peripheral devices and a WDT function. It also performs the charge controlling of the short-term backup
battery during this time.