Commodore MPS-801 - Page 12

4. Carrier Return Operation
After printing a line, the CPU sets the MOT signal (P5/30) HIGH and the HC signal (P5/29) LOW.
The motor then stops and the print head begins to return to the home position because it is pulled
by the recovery spring. If a carrier return operation includes a line feed, the CPU sets the LFPW signal
(P5/28) LOW and drives the stepping motor about 10ms later. Refer to the linefeed flowchart.
After performing a line feed, the CPU waits until the HOME signal goes HIGH, which means the print
head has returned to the home position.
When the HOME signal becomes HIGH, the CPU sets the HC signal HIGH, about 160ms later, ending
the carrier return operation.
MOT (P5/30)
HC (P5/29)
HOME (TEST PIN)
LFPW
DRIVE
TIMING
LF1 (P3/4)
LF2 (P3/3)
LF3 (P3/6)
LF4 (P3/5)
~----------~!i~-------------~---1-w-m~s~
I I
r----110ms
I
I 20V
t
I I
1 3 5 7 9 11 13 15 17 19 21 23 24
8.4 msl:-:H II I I I I I I I I I I I I I I I I I H
1
2
.
5
y-3.0V
i
I
1/144 inch is the smallest unit of movement and occurs when the LF stepping motor is driven one
step. 24 pulses of the DRIVE TIMING perform a line feed of 24 X 1/144 = 116 inch.
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