Circuit Board Components - Canon FAX-L350 Service Manual

FAX-L350 Chapter 2: Technical Reference

5.2 Circuit Board Components

a) System control section
The system controller is made up of the following components, and controls the entire fax system.
a-1) MPU (Micro Processor Unit) (IC26)
The main functions of the NEC µPD703102GJ-A33 MPU are as follows:
• 32 bit CPU
• 16 bit address bus
• 16 bit data bus
• DMA control
• A/D converter
• Software CODEC
• Interrupt control unit
a-2) System controller (IC10)
The system controller is a gate array for controlling MPU peripheral devices. The main functions of the
system controller are as follows:
• Printer resolution conversion (Smoothing)
• LBP video interface
The LBP video interface transfers print signals to or from the printer controller and sends them to the
MPU. The interface transmits an image signal (nVDO) and a vertical sync signal (nTOP) to the printer
section, receives a horizontal sync signal (nBD) and printer section status from the printer section and
transfers them to the MPU.
• OPCNT serial interface
• DRAM/SRAM controller
Controls DRAM/SRAM read/write and refreshing.
• Document feed motor control
• Reduction in vertical scanning
• Recording decoder
• Pickup solenoid control
• RTC (Real Time Clock) control
The RTC is backed up by lithium battery, and counts the data and time.
• SRAM
SRAM is backed up by lithium battery. SRAM holds data registered for system control and communi-
cations management information.
a-3) Main ROM (SOC1)
This 16 Mbit ROM contains the control programs (e.g. operation panel, scanner and communications
section etc.) for this fax.
a-4) DRAM (IC9)
This 64 Mbit is used as memory for storing image data, and as an MPU work area.
b) Communication control section
Modem IC (IC36)
A Conexant R288F-26 (PLCC type) is used as the MODEM IC. The MODEM IC carries out G3 modula-
tion conforming to ITU-T standards V.34, V.29, V.27ter, V.21 and V.8 on transmitted data received from the
MPU during transmission. During reception, the MODEM IC carries out G3 modulation on received
signals from the telephone line, according to the same standards.
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