Sharp SF-1020, SF-1120 Stepping motor PAM1, PAM2 drive circuit, ADU motor DDM drive circuit

Pin	Used	Sig. Name	I/O	Active	Note
No.	Port
42	A6				Address signal
43	A5				Address signal
44	A4				Address signal
45	A3				Address signal
46	A2				Address signal
47	A1				Address signal
48	A0				Address signal
49	D0				Data signal
50	D1				Data signal
51	D2				Data signal
52	D3				Data signal
53	D4				Data signal
54	D5				Data signal
55	D6				Data signal
56	D7				Data signal
57	P4-0	DPFC	O	H	Take-up roller clutch signal
58	P4-1	DRRC	O	H	Transport roller clutch signal
59	P4-2	PS	O	— Not Used
60	/RD				ROM READ pin
61	/WR				Stepping motor data
					WRITE pin
62	/AS				Address strobe pin
					(H-lev. fixed)
63	/CLK				System clock pin
					(H-lev. fixed)
64	/WAIT				Wait pin (H-lev. fixed)

(3) Stepping motor (PAM1, PAM2) drive circuit

The write data is latched by the HC374 at the writing timing of exter- nal address. When the stepping motor output signal (P6-0) becomes LOW, the excitement signal of the stepping motor is sent to the transistor array IC of IC2, 3, driving PAM1 and PAM2.

Write address	Data bus	Drive signal	ACT
H'FF80	D0	PAM1 A	H
H'FF80	D1	PAM1/A	H
H'FF80	D2	PAM1 B	H
H'FF80	D3	PAM1/B	H
H'FF80	D4	PAM2 A	H
H'FF80	D5	PAM2/A	H
H'FF80	D6	PAM2 B	H
H'FF80	D7	PAM2/B	H

*The power source is driven by VB.

Stepping motor time chart

A

B

A

B

A

Phase A

+24V

Phase A

A Phase B Phase B

B +24V B

A:Stepping motor phase A coil drive circuit

B:Stepping motor phase B coil drive circuit

A:Stepping motor phase A coil drive circuit

B:Stepping motor phase B coil drive circuit

(4) ADU motor (DDM) drive circuit

The CPU supplies signals of two systems, which are process by the hardware to drive DDM.

Drive and non-drive speed control is performed with DDM_PWM, and normal/reverse rotation of the motor is performed with DDM_DIR. When paper enters the ADU, DDM is driven with DDM_DIR at LOW, Q3 ON, and Q1 OFF.

When paper enters the ADU, DDM is driven with DDM_DIR at LOW, Q3 is turned ON and Q1 is turned OFF.

When DDM_PWM is HIGH, Q2 is turned OFF and Q4 is turned ON by Q3.

In IC8, therefore, A-OFF, B-ON, D-OFF. The motor current flows through VH → B → M → C → GND to drive the motor.

The motor rotation is controlled with the PWM control.

When paper is discharged from the ADU, DDM_DIR is HIGH, Q3 is turned OFF and Q1 is turned ON.

When DDM_PWM is HIGH, Q4 is turned OFF and Q2 is turned ON by Q1.

In IC8, therefore, A-ON, B-OFF, C-OFF, D-ON. The motor current flows through VH → A → M → GND to drive the motor.

The motor rotation is controlled with the PWM control.

When the motor is not driven, DDM_PWM and DDM_DIR are LOW.

12 – 20