Brother LX-200 Service Manual page 114

Port
P61
P60
P77
P76
P75
P74
P73
P72
P71
P70
Clock Circuit
The main CPU incorporates a clock-generation circuit which uses externally
mounted components. This circuit and the main CPU internal circuit generate an 8
MHz clock signal.
Reset Circuit
This circuit resets the main CPU when the power is turned ON or OFF. M51953 is
used as the reset IC in this circuit.
When the power is turned ON, the reset IC holds the reset output Low for
approximately 30 ms after the +5V DC power supply applied voltage reaches 4.25 V.
After this period the reset output becomes High to clear the main CPU reset status.
When the power is turned OFF, after the +5V DC power supply applied voltage
drops to 4.25 V, or below, the reset IC sets the reset output Low to reset the main
CPU.
Pin No. I/O
57 IN
56 IN
8 OUT
7 OUT
6 OUT
5 OUT
4 OUT
3 OUT
2 OUT
1 OUT
Fig. 5.3-2 Clock Circuit
Fig. 5.3-3 Reset Circuit
5-6
CSEL A
TPS
T/C MOTOR PHASE B
T/C MOTOR PHASE A
T/C MOTOR PHASE D
T/C MOTOR PHASE C
LF MOTOR PHASE B
LF MOTOR PHASE A
LF MOTOR PHASE D
LF MOTOR PHASE C