Specifications

Appendix B
CR Motor Drive Circuit
Figure B-7 shows the CR motor drive circuit, which uses an open-loop, constant-
current drive control to drive the CR motor. The motor is driven with 2-2 phase
excitation and 1-2 phase excitation. The 2-2 phase excitation corresponds to two 1-2
phase excitation steps, so for each single step phase change of a 2-2 phase excitation
motor, the carriage moves 1/120 inch. For each single step phase change of a 1-2
phase excitation motor, the carriage moves l/240 inch.
The CR motor drive circuit of the STK-67128 detects the amount of current flow in
the CR motor coil and regulates it. The current flowing through the coil varies
depending on the speed of the CR motor. The amount of current is set by the CPU
via the E05A50 I/O port. Signals are sent to Vrefl or Vret2 on the STK-67128. The
SIX-67128 sets the coil current to correspond to the CR motor speed. Ports P60 to
P63 on the CPU are used exclusively as phase control ports for the stepping motor.
TMP90CO41
ml) I
STK6712
P62
P63
IAl
60
ml
E05A50
MC
AX
Figure B-7. CR Motor Drive Circuit
CR MOTOR
Drive Mode
Table B-9. CR Motor Drive Modes
Excitation Type
Type Drive Frequency
Standard Print Character
3 x speed
2-2 phase
2 x speed
2-2 phase
1.5 x speed
2-2 phase
443 x speed l-2 phase
1 x speed
l-2 phase
314 x speed l-2 phase
2l3 x speed l-2 phase
II2 x speed l-2 phase
2695 pulses per second (pps)
1773 pps
1347 pps
1191 pps
1796 pps
1347 pps
119opps
698 pps
Drafi
High speed LO
Draft (emphasized, condensed)
LQ
B-12
Epson LQ-570+/1 070+