Epson PhotoPC 800 Service Manual page 45

EPSON PhotoPC 800
Table 2-9. 8-bit Microprocessor Port Specification
Pin Signal Name I/O
91~94 SCAN OUT 0 3 O
95 LCD ON O
96 /ASIC TEST O
97 /ASIC RESET O
98 /MAIN RESET O
99 AVSS --
100 BATTERY I
Operating Principle
Outline
Key matrix output
DC/DC converter (LCD system) ON/OFF
signal
ASIC control signal
ASIC reset signal L:Reset output
SPARC reset signal L: Reset output
Analog GND input terminal
Battery voltage input (analog input)
Operating principles of the Circuit Boards
2.2.3.2 Internal Communication Bus
The SY1 circuit board carries out overall control of camera operation by
detecting the input from the keyboard and the condition of the camera circuits.
The 8-bit microprocessor reads the signals from each sensor element as input
data and outputs this data to the camera circuits (ASIC) or to the LCD display
device as operation mode setting data. The figure below shows the internal
communication between the 8-bit microprocessor, ASIC and SPARC lite
H:ON
circuits.
Microprocessor
Figure 2-14. Internal Bus Communication System
Revision A
45