Principles of Operation

Control Circuit Operation

The control circuit consists of two circuit boards: the CO94 MAIN (main control circuit board) and the CO94 PNL (control panel circuit board). This section describes the operation of these boards.

Control Circuit Operation Overview

The CPU on the CO94 MAIN is an 8-bit TMP9OCO41F microprocessor (9.83 MHz). It oversees control of all the components of the printer. The E05A66YA gate array contains various memory management functions that control the memory assignment and J/O areas. The output signals fkom each detector are sent to the analog input port of the CPU. The signals from the control panel are sent to the gate array, which in turn, sends LED signals to the control panel. The two motors (CR and PF) are controlled by signals sent from the stepping motor control port of the CPU. Figure 6-23 shows the control circuits in block diagram form.

II

-I-

E’PROM

 

 

PSRAM

MASK

 

 

‘-1 pzG=L

I 4K BIT

 

I

 

ROM

I

I 1M BIT

I I -.* -.-

 

-

w

1

CONTROL

1

I

I

PANEL

 

 

 

BUlTONS

 

 

 

AND LEDS

I

I

+j1 ~i%k%E

 

 

 

 

 

 

 

 

s +6VDC

m Data bus

-

 

w +36VDC

Address

bus

 

 

 

Figure! 6-23. Control Circuit Block Diagram

6-22

Epson FX-87W1170