Eeprom Control Circuit; Sensor Circuit - Epson Stylus Color C70 Service Manual

EPSON Stylus COLOR C70/C80

2.2.2.5 EEPROM Control Circuit

Since EEPROM is nonvolatile memory, it keeps written information if the printer
power is turned off. When the printer is turned ON, CPU (IC7) reads data from
EEPROM (IC6 : Stylus COLOR C70, IC18 : Stylus COLOR C80) via the RAM and
when the power is turned OFF it stores data to EEPROM via the RAM.
Information stored in EEPROM is listed below.
Various ink counter (I/C consumption counter, waste pad counter, etc.)
Mechanical setting value (Head ID, Bi-D adjustment, USB ID, etc.)
See Table 7-8, "EEPROM Address Map," on page 187 that provides detailed
information on the values stored in EEPROM.
IC18 (IC6)
+5V
EEPROM-93C
8
VCC
7
NC
6
ORG
5
GND
Figure 2-31. EEPROM Circuit Diagram
EEPROM is connected to CPU with 4 lines and each line has the following function.
CS: Chip selection signal
SK (CLK): Data synchronism clock pulse
DI: Data writing line (serial data) at power off.
DO: Data reading line (serial data) aPEPEt power on.
NOTE: Items with brackets are for the C80, and items without brackets are for
the C70.
Operating Principles
+5V
IC7
E01A27CA
1 (5)
166
ECS
CS
167
SK 2 (4)
ECK
(CLK)
3 (3) 168
EDO
DI
171
4 (2)
EDI
DO
Electrical Circuit Operating Principles

2.2.2.6 Sensor Circuit

C424 MAIN-B is equipped with the following one sensor to detect the status of the
printer. Unlike the previous product, ASF HP sensor and HP sensor are not equipped
and the ASF HP is determined with the clutch mechanism ("Paper Feeding
Mechanism").
PE Sensor
This sensor uses photo interrupter method and detects the following two status.
The photo interrupt component and two detection levers consists of this sensor.
Paper Top & End position
When the Paper is in the paper path, this sensor outputs the HIGH signal.
When the Paper is not in the paper path, this sensor outputs the LOW signal.
This status is always monitored during the printer is in the power on status
with this sensor.
Thermistor (THM)
The thermistor is attached directly on the printhead driver board. It monitors the
temperature around the printhead and determines the proper head drive voltage
according to the ink viscosity that varies by the temperature. This information is
fed back to the CPU analog port. When the temperature rises, the head drive
circuit lowers the drive voltage: When the temperature lowers, the head drive
circuit rises the drive voltage. This circuit is different from head inside
temperature detection circuit. (Please refer to page -56 for details.)
Linear Scale & CR Encoder
To make the current CR position manage, CR encoder always monitors the bar-
code on the linear scale during CR motor drivers. Also this model has no HP
sensor and judges the home position when the CR goes out of step at right side.
Rotary Scale & PF Encoder
To make the paper feed pitch precisely. PF encoder always monitors the bar-code
on the rotary scale during PF motor drivers.
The block diagram for the sensor circuit is shown below
Revision A
58