4255 查看數據表（PDF） - Allegro MicroSystems

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产品描述 (功能)

生产厂家

4255

8-Bit microcontroller

Allegro MicroSystems 

4255

8-BIT

MICROCONTROLLER

FUNCTIONAL DESCRIPTION (cont’d)

format, reset, 1/8th vs 1/16th sub-steps, etc. Note that

during power up, shift clock (SCLK) is sampled for a pull-

up or pull-down resistor to establish the fractional step

limit. A pull up sets up a 1/8th-step format (for the

A3955) and pull down sets up 1/16th-operation (for the

A3957).

Table 2 lists the microcontroller terminal descriptions

and provides the essence of the circuit operation (a

schematic illustrating a typical stepper design follows). A

brief description of the microcontroller I/O should clarify

the connections of the various elements of the drive

electronics.

Table 1 — Controller/sequencer IC operational logic

Binary inputs

DIR MS2 MS1 MS0

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

1011

1100

1101

1110

1111

Operating mode

(Command executed on L → H of CLK)

CW, Full step (single-phase)

CW, Half step (constant torque)

CW, 1/4 step (constant torque)

CW, 1/8th step (constant torque)

CW, 1/16th step (constant torque)

Disable A3955/57 holding torque

Enable A3955/57 holding torque

Reset A4255 sequencer IC

CCW, full step (single-phase)

CCW, half step (constant torque)

CCW, 1/4 step (constant torque)

CCW, 1/8th step (constant torque)

CCW, 1/16th step (constant torque)

Disable A3955/57 holding torque

Enable A3955/57 holding torque

Reset A4255 sequencer IC

Comments

(Applicable power ICs)

A3955/57

A3955/57

A3955/57

A3955/57

A3957 only

At present position

From present position

A3955/57

A3955/57

A3955/57

A3955/57

A3955/57

A3957 only

At present position

From present position

A3955/57

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