EPSON Stylus COLOR 440, 640, and 740 Chapter 2 Operating Principles
54
CPU
The 16-bit CPU
IC1
runs at 25 MHz and performs the printer’s data
processin
and memor
mana
ement functions. This includes sendin
out the CAS and RAS refresh si
nals re
uired b
the DRAM.
Gate Array
The
ate arra
IC2
is the main hub for transmittin
control si
nals and
receivin
data. It interfaces with the followin
devices:
Paper Feed and Carria
e Motor Drivers
The
ate arra
outputs motor control si
nals to the PF and CR
motor drivers.
Printhead Driver
The
ate arra
outputs control si
nals to the PH driver.
EEPROM
Default settin
s, records of previous printhead cleanin
s, ink
cartrid
e usa
e, ink waste pad count, and ad
ustment values are
stored in the EEPROM. The
ate arra
retrieves these data when
the printer is first turned on, and writes data to the EEPROM at
power-off.
Sensors
The printer contains 6 sensors. Of these, 5 feed data directl
to the
ate arra
.
The thermistor connects to the CPU.
Power-Off Timer
The
ate arra
receives information from a timer that monitors how
lon
the printer is turned off. When the printer is turned back on, the
level of cleanin
the printer performs on the printhead depends on
how lon
the power has been off.
Serial I/F Control
St
lus COLOR 740 onl
The
ate arra
receives serial port data throu
h the transceiver IC.
Parallel I/F control
Usin
IEEE1284 Nibble mode, the
ate arra
not onl
receives data
from the host computer but can also return information about the
printer’s status.
USB I/F Control
St
lus COLOR 740 onl
The transceiver circuit that controls the USB interface has been
incorporated into the
ate arra
.
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