Cpu; Gate Array - Epson Stylus COLOR 440 Service Manual

EPSON Stylus COLOR 440, 640, and 740

CPU

The 16-bit CPU (IC1) runs at 25 MHz and performs the printer's data
processing and memory management functions. This includes sending
out the CAS and RAS refresh signals required by the DRAM.

Gate Array

The gate array (IC2) is the main hub for transmitting control signals and
receiving data. It interfaces with the following devices:


Paper Feed and Carriage Motor Drivers
The gate array outputs motor control signals to the PF and CR
motor drivers.


Printhead Driver
The gate array outputs control signals to the PH driver.


EEPROM
Default settings, records of previous printhead cleanings, ink
cartridge usage, ink waste pad count, and adjustment values are
stored in the EEPROM. The gate array 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 directly to the
gate array. (The thermistor connects to the CPU.)


Power-Off Timer
The gate array receives information from a timer that monitors how
long the printer is turned off. When the printer is turned back on, the
level of cleaning the printer performs on the printhead depends on
how long the power has been off.


Serial I/F Control (Stylus COLOR 740 only)
The gate array receives serial port data through the transceiver IC.


Parallel I/F control
Using IEEE1284 Nibble mode, the gate array not only receives data
from the host computer but can also return information about the
printer's status.


USB I/F Control (Stylus COLOR 740 only)
The transceiver circuit that controls the USB interface has been
incorporated into the gate array.
Chapter 2 Operating Principles
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