Logic Section Components - Canon BJC-5000 Service Manual

Part 4: Technical Reference
BJC-5000

4.2.2 Logic section components

1) MPU & printer controller
The MPU contains a 16-bit CPU, 512K-byte work RAM, 24-bit address bus port, 16-
bit data bus port, stepping motor controller, A-D converter, interface controller,
printhead controller, buffer controller, DRAM controller, EEPROM controller, I/O
ports, and other components.
Built-in CPU
The 16-bit CPU operation is synchronized with a 25MHz external clock input.
Address bus
Bits A1 to A20 of the 24-bit address bus port are connected to an 8M-bit control
ROM (the 4 bits from A21 to A23 and A0 are not used). Chip selection of the control
ROM is performed by the read signal output by the MPU & printer controller.
Data bus
Like the address bus, the 16-bit data bus port is also connected to the 8M-bit
control ROM.
Stepping motor controller
The stepping motor controller outputs the two-phase excitation drive signals of the
carriage motor and paper feed motor.
A-D converter
The following analog signals are detected after they pass through the built-in A-D
converter:
AN0: The printer's internal temperature, print position information, and ink
reflection density are detected by the thermistor on the logic board selected by the
multiplexer, and the auto-alignment sensor on the carriage.
AN1: The head temperature and head rank in the RIGHT BJ cartridge are detected
by the rank resistor and head temperature sensor in the RIGHT BJ cartridge
selected by the multiplexer.
AN2: The head temperature and head rank in the LEFT BJ cartridge are detected by
the rank resistor and head temperature sensor in the LEFT BJ cartridge selected by
the multiplexer.
Interface controller
The interface controller receives, from the computer, 8-bit parallel data which is
synchronized with the data strobe pulse (STROBE) through the BUSY/ACKNLG
handshake. It also controls other interface signals.
Data received through the interface is stored in the DRAM's receive buffer and
analyzed by the MPU & printer controller.
When the printer initialization signal INIT is input through the interface to the MPU
& printer controller, the MPU & printer controller output a BUSY signal. Also, after
the print data in the print buffer is printed, the printer is initialized.
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