UM0886
System overview
Doc ID 16916 Rev 1
13/30
The paper is fed in a forward direction when the motor shaft is rotating in the normal
direction (clockwise) as seen from the motor gear side. The motor is driven by a 2-2 phase
excitation, constant-current chopper method and feeds 0.125 mm of paper (equivalent to a
single dot pitch) every two steps of the motor drive signal. It is not possible to print while the
motor is rotating in the reverse direction.
Excitation sequence
As shown in
, the printer feeds the paper in the normal direction when the motor is
excited in the order of step 1, step 2, step 3, step 4, step 1, step 2... On the other hand, to
rotate the motor in the reverse direction, the motor must be driven in the reverse order: step
4, step 3, step 2, step 1, step 4, step 3, etc.
Figure 10.
Truth table for excitation sequence
Figure 11.
Timing diagram for excitation sequence
4.1.4 Alphanumeric
LCD
A 16 by 2 cm alphanumeric LCD displays the entries entered through the keypad.
4.1.5 EEPROM
The EEPROM maintains records and stores the last 20 entries.