Service manual

BJC-4300
Part 4: Technical Reference
4.2.2
Logic section components
1)
MPU
(ICl)
The MPU contains a 16.bit CPU,
lK-bit
RAM, 24.bit address bus port,
16.bit
data
bus port, stepping motor controller, interrupter controller, A-D converter,
I/O
ports.
and other components.
Built-in CPU
The 16.bit CPU operates in synchronization with a 20 MHz external clock input.
Address bus
The 24.bit address bus port is connected to an 8 M-bit control/CG ROM and printer
controller. The controller/CG ROM synchronizes with the read signals output by the
MPU and the 20 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-bit
control/CG ROM and printer controller.
Stepping motor controller
The stepping motor controller outputs the carriage motor single- and two-phase
exciter drive signals and paper feed motor two-phase drive signals.
The stepping motor controller switches the carriage motor with the B-step peak
current value for optimum drive. The stepping motor controller outputs the
switching control signal to the carriage motor driver.
Interrupt controller
For external interruption, the MPU has ports
PSO.
8
1,
84, 85, and 87 to receive the
POWER button on/off switching, data reception, initial interrupt request. receive
buffer-full warning. and other signals. The MPU executes interrupt processing for
the respective signals.
A-D converter
The following analog signals are detected after they pass through the built-in A-D
converter:
ANO:
The printer’s internal temperature is detected by the thermistor on the logic
board.
AN 1: The head temperature is detected by the head temperature sensor in the EJ
cartridge.
AN3: The head rank is detected by the rank resistor in the
BJ
cartridge.
I/O
port
The setting status determined by the head ID, paper end sensor, home position
sensor. and pick-up roller sensor are input through the input ports. The buzzer, BJ
cartridge detection, head-driving voltage control, and other signals are output from
the output ports.
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