Functions Of The Cpu - Epson LX-HOO Technical Manual

2 . 4 . 1 F u n c t i o n s o f t h e C P U
The core of the control circuit is the 78 10H CPU (IC2B). Table 2-3 shows the function of each pin and
the related circuits.
Pin Port
Assignment
Number
2
3
4
' - 5
6
7
8
9
16
17
18
19
20
21
22
23
24
Table 2-3. CPU Port Assignments
Signal Line
Name
o
holding voltage. When this signal is HIGH (LOW), the drive
voltage (holding voltage) is applied to the carriage motor.
Not used.
o
holding voltage. When this signal is HIGH (LOW),
voltage (holding voltage) is applied to the paper feed motor.
LF SW
I
control panel.
control panel.
I PE SW
paper is loaded, this signal goes LOW.
Not used.
- 8
I
o
in the CPU to the TXD (transmit data to the host computer)
terminal of the optional interface.
I
optional serial interface board (for serial/parallel data conver-
sion) is connected. (Data reception detection)
o ONLINE LP
this signal is LOW, the LED lights.
INT2 input port. Reads the state of the ON LINE switch on the
I
control panel. Connected to the interrupt controller in the CPU,
which executes the ON LINE/OFF LINE switch interrupt routine
when this signal is LOW.
o
the printer is in an error state. When this signal is LOW, the
printer is in an error state.
port.
ACKNLG
o
signal is LOW active.
0 FIRE COO output port. Outputs the drive pulse width signal, which is
determined by the timer/event counter in the CPU, to the FIRE
terminal of gate array E05A03. This
0 BUZZER
this signal is LOW, the buzzer rings.
Description
Outputs the acknowledge signal to the interface. This
2-11
REV.-B
drive
the
signal
is LOW active.