Control Section Components - Canon BJC-55 Service Bulletin

Part 4: Technical Reference

4.2.2 Control section components

a) ASIC (IC6)
The ASIC is comprised of the MPU section and the printer controller section. It has
a built-in 16-bit CPU and the operating synchronized frequency is 23.04 MHz. The
printer controller's operating synchronized frequencies are 23.04 MHz and 24.00
MHz. The MPU section and the printer controller section operate in synchronization.
1) MPU
Address bus
The 21-bit address bus ports is connected to an 4 M-byte flash ROM and 8 M-byte
FONT ROM. The flash ROM/FONT ROM synchronizes with the read signals output by
the MPU and the 23.04 MHz clock signal. The printer controller then selects the chip.
Data bus
Like the address bus, the 16-bit data bus port is connected to the 8 M-byte FONT
ROM.
Stepping motor controller
The stepping motor controller outputs the carriage motor micro-step control
signals and paper feed motor's double-phase exciter drive signals and single-and
double-phase exciter drive signals.
Interrupt controller
For external interruption, the MPU has POWER button on/off switch, data
reception, initial interrupt request and other signals. Each signal is inputted to
each port and interrupt processing is executed.
A/D converter
The following analog signals are detected by the built-in A/D converter. The
signals from four A/D ports are divided into two groups (A and B) with 4 signals
per group. Use the external analog switch to select a group.
A/D port
AD0
AD1
AD2
AD3
Use the output LPC2 as the analog switch. All inputs will be connected to the A/D
port of ASIC when LPC2 is set to either "0" for Group A or "1" for Group B.
EEPROM write/read control
The TE-CLK signal output from the ASIC is EEPROM's clock signal. The recorded
data in the EEPROM is read using the TOE signals. The read-out data is output
from the ASIC by the TEDIO signals and written on the EEPROM using EDO
signals.
I/O port
The following signals are inputted to the input port: (i) signals from the POWER ,
RESUME and CARTRIDGE buttons and (ii) EEPROM read signals. The output
signals outputs flash ROM rewrite signals and recharge LED ON/OFF signals.
Group A
Head ID
Head Temperature
Head Rank
Printer Internal Temperature
Group B
Voltage input
Recharging Battery Voltage
Recharge Current
Battery Temperature
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