Avt 3225 User manual

This controller allows the construction of advanced

mock-up mechanisms, extension of machines and

tools such as milling machines or drills but can also

be useful in photography to build a drive for taking

timelapses and 360º photos.

Controller allows stepper motors bipolar (4-wire) and

unipolar (5-, 6- or 8-wire) to be continuously adjusted

in speed and direction using a single potentiometer.

Features

• infinitely variable speed and direction of rotation

(with the same potentiometer)

• speed control divided into two ranges

(1 ÷ 10 and 7 ÷ 100 cycles per second)

• microstep control with 1/64 or 1/8 step resolution

• suitable for bipolar (4 wires) and unipolar

(5 or 6 wires) motors

• timer function, time steplessly adjustable

from 0.5 ÷ 70 s

• supply voltage range (rated motor voltage) 8 ÷ 25 V

• output current up to 2 A per channel (coil)

Range of changes in the speed of the motor axis is

divided into two sub-ranges of 1...10 or 7...100 cycles

per second. This selection can be made using the

appropriate jumper. Microstep control with a

resolution of 1/64 or 1/8 step. Microstep operation

involves rotating the magnetic field of the stator in a

much smoother way than in full and half-step control.

By working with the microstep, smaller steps and

more accurate positioning can be achieved. When the

motor is controlled at low frequencies with a full step

or half-step, the movement becomes discontinuous

and is characterised by high levels of noise and

vibration. With a small step, the energy provided to

the rotor at one step is only a fraction of the energy

of a full step and is so small that it can easily be

absorbed and cushioned by the internal friction in the

motor and its inertia. No vibration is then generated,

and the motor rotor will not run out at any time

beyond its desired position. Microstep control also

enables much quieter motor operation. The controller

Circuit description

Universal Stepper Motor

Controller

AVT 3225

kits

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ASSEMBLY DIFFICULTY

PDF

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described must be supplied with voltage in the range

8...24 VDC and the maximum output current is up to 2

A/channel (coil) with appropriate heat sink. Without

the heat sink, the controller can safely be used with

up to 250 mA per channel/coil. In addition, the

controller is equipped with a timer function (time is

continuously adjustable in the range of 0.5...70 s). The

START/STOP jumper configures the controller for

continuous or timed operation. Time is set using a

potentiometer and the countdown is triggered by

briefly short-circuiting the jumper pinsSTART/STOP.

Figure 1 shows the configuration of the controller

along with the most important elements of its design.

Schematic diagram of the circuit is shown in Figure 2.

Correct power supply is ensured by the 7805 stabiliser

together with capacitances C1-C4. Power stage is

implemented on the well-known L298 IC, which

incorporates two H-bridges. Its operation is

controlled by an ATtiny261 microcontroller, or more

precisely by a program in its memory. Micro-step

control is achieved by controlling the motor windings

with a PWM waveform. The PWM modulation

characteristics are triangular in shape. Such a solution

is uncomplicated and effective in most cases of motor

operation. Jumpers on the controller board are used

to configure the circuit. The jumper described as

HFRQ/L-FRQ is used to change the speed sub-band. If

fitted, a higher sequence frequency will be selected,

approximately 7...100 cycles per second (i.e., full

waveform periods per channel). The circuit operates

at a lower resolution of 1/8 step. Absence of a jumper

means a lower sequence frequency, i.e., approximately

1...10 cycles per second, and a higher microstep

resolution of 1/64. The STAT/DYN jumper determines

whether the motor will be de-energised during

standstill - static standstill (jumper on), or the power

supply will be maintained - dynamic standstill

(jumper off). At a static stop, almost free motor shaft

movement is possible, during dynamic stop, the

motor shaft is locked in its position, and here it must

be remembered that current flows through the coils,

which will cause the motor to heat up. This controller

has a timed operation function. It is switched on when

the START/STOP connector is short-circuited and lasts

for a time proportional to the position of

potentiometer PR1. Time is counted from the

moment the START/STOP jumper is removed. It is best

to replace the jumper with a reset-type monostable

button. If the jumper remains on, the controller will

operate at all times. A potentiometer attached to

screw connector X1 is used to adjust the direction and

speed - in the middle position the motor is stopped,

turning the potentiometer causes a gradual Increase

of its speed. Instead of this potentiometer, a

potentiometer joystick can be attached, in which case

the rotation of the motor will be proportional to the

direction and angle of the joystick.

Fig. 1.

STOP L-FRQDYN

US1

PR1

LED1

STAT H-FRQ

START

X2 X3

US2

US3

STAT

H-FREQ

START

DYN

L-FREQ

STOP

SPEED AND DIRECTION

Fig. 2. Schematic diagram

7805

10k

100n100n220uF 10uF

100n

GND

V+

GND

+5V

1k G

L298

GND

V+

GND

8×1N5817ATTINY261

GND

1N5817

RHW

V+

GND

+5V +5V

+5V

GND

+5V +5V

L-FREQ

DYN

STOP

GND

IN OUT

US1

PR1

C3C2C1 C4

R2 LED1

SEN_B 15

OUT4 14

OUT3 13

INPUT4

ENABLE_B

INPUT3

VCC

GND

INPUT2

ENABLE_A

INPUT1

VS 4

OUT2 3

OUT1 2

SEN_A 1

US3

D1 D2 D3 D4

D5 D6 D7 D8

(ADC8/XTAL2)PB5 8

(ADC7/XTAL1)PB4 7

(SCK/SCL/OC1B)PB2 3

(MISO/DO/OC1A)PB1 2

(MOSI/DI/SDA/OC1A)PB0 1

(ADC6/AIN1)PA7 11

(ADC5/AIN0)PA6 12

(ADC4)PA5 13

(ADC3)PA4 14

(AREF)PA3 17

(ADC2)PA2 18

(ADC1)PA1 19

(ADC0)PA0 20

GND

VCC

AVCC

(ADC10/RESET)PB7 10

(ADC9/INT0/T0)PB6 9

GND

US2

2STAT

2H-FRQ

X1-1

X1-2

X1-3

2START

X2-1

X2-2

X3-1

X3-2

X3-3

X3-4

RST

LED

JP1

JP2

JP3

DIR

TIME

Mounting and start-up

Appearance of the printed circuit is shown in Figure 3.

Controller board dimensions are 33×83 mm. The

circuit is built using through-hole components, so this

mounting can be performed by even less experienced

hobbyists. Correctly assembled circuit is operational

as soon as it is energized. If the motor will draw more

than 250 mA per channel, the L298 circuit requires an

additional heat sink. It is recommended to

additionally solder 0.8-1 mm silver foil on the

exposed, i.e., not soldermasked, tracks to further

improve the current-carrying capacity of the tracks.

This applies when the current of one coil/channel will

exceed 500 mA. The circuit has been designed to

control the propulsion of the camera trolley

. It is perfect for achieving very low stepper motor

speeds. Note, however, that despite the high

resolution of the microstep control, on some motors

the shaft movement may not be perfectly smooth and

slight vibrations may occur. Therefore, it is best to

choose motors with a high number of steps per

revolution, e.g. 200 (1.8°) or 400 (0.9°).

Fig. 3 Mounting diagram

List of components

Resistors:

R1, R2:..................1 kΩ

PR1:.......................mounting potentiometer 10 kΩ

Capacitors:

C1: .........................220 μF

C2, C3, C5: ..........100 nF

C4: .........................100 μF

Semiconductors:

D1-D9:..................1N5817

LED1:.....................LED 3mm (any colour)

US1:.......................7805

US2:.......................ATtiny261

US3:.......................L298

Other:

L1: .........................ferrite bead

X1: .........................ARK3/5 + potentiometer 10 kΩ

X2: .........................ARK2/5

X3: .........................2×ARK2/5

goldpin 6 straight pins + 3 Jumpers

Start mounting from soldering the components onto the board in order of size from

smallest to largest. Photographs of the mounted kit may be helpful. To access the high-

resolution images as links, download the PDF.

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AVT SPV reserves the right to make changes without prior notice.Installation and connection of the appliance not in accordance with the instructions, unauthorised modification of

components and any structural alterations may cause damage to the appliance and endanger persons using it. In such a case, the manufacturer and its authorised representatives shall

not be liable for any damage arising directly or indirectly from the use or malfunction of the product.

The self-assembly kits are intended for educational and demonstration purposes only. They are not intended for use in commercial applications. If they are used in such applications, the

purchaser assumes all responsibility for ensuring compliance with all regulations

This symbol means do not dispose of your

product with your other household waste.

Instead, you should protect human health

and the environment by handing over your

waste equipment to a designated collection

point for the recycling of waste electrical

and electronic equipment.

Leszczynowa 11 Street,

03-197 Warsaw, Poland

https://sklep.avt.pl/

AVT SPV Sp. z o.o.