Epson TM U200D - B/W Dot-matrix Printer, Technical Manual

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2-24 Mechanism Configuration and Operating Principles Rev.B
DIP switch read circuit
There are 8 switches in DIP switch bank 1 and 2 switches in DIP switch bank 2 that are status
readable switches. Each signal is input to the CPU. The signal is read as
LOW when the switch is
On, and HIGH when the switch is Off.
CPU (U5) pin 52 to 55, pin 56 to 59, and pins 1 and 81 are also used for the Motor, carriage drive
circuit, Motor, paper feed drive circuit, and operation panel control circuit. The pins are used to
read DIP switches temporarily immediately after the printer initialization (or the power is
turned on).
(*1): Resistance between E and B is used for pull-up resistors in the transistor.
Figure 2-23 DIP switch read circuit
{
5V
52
53
54
55
56
57
58
59
P20
P21
P22
P23
P90
P91
P92
P93
1 2 3 4 5 7 6 8
DSW1
U5
D24 D23 D22 D21 D20 D19 D18 D17
Q14 Q15 Q16 Q17 Q18 Q19 Q20 Q21 Q36 Q35
D14 D25
1 2
DSW2
1
80
P57
P56
R33
{
5 V
Q39
Q28
Q38
R32
{
5 V
R29
{ 5 V
3
P100
4
P101
( 1)
(*1)