Difference: Motors (2 vs. 3)

Revision 32020-06-25 - UliRaich

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Motors

Introduction

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Gnd	brown	Gnd
Power	red	3.3V
Signal	orange	any GPIO pin, default: D0, on ESP32: GPIO 26

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I wrote and integrated into the MicroPython binary a simple servo driver which makes it extremely simple to control the servo motor:

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I wrote and integrated into the MicroPython binary a simple servo driver which makes it extremely simply to control the servo motor:

from servo import Servo
servo = Servo()
servo.angle(90)

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from servo import Servo 
servo = Servo() 
servo.angle(90)

will move the servo to 90 degrees.

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Stepping Motor

In order to learn about how stepping motors work please refer to the 2017 course on embedded systems lecture 9: UCC_Course/Lecture9:SteppingMotors. We will use a 27BJY-48 stepper motor with its associated ULN-2803 driver module. http://robocraft.ru/files/datasheet/28BYJ-48.pdf is the data sheet of the motor and https://www.sparkfun.com/datasheets/IC/uln2803a.pdf is the datasheet of the ULN-2803 Darlington Transistor array.

The stepping Motor class included in the MicroPython binary uses the following default connections

Pin on the driver module	pin on the ESP32
5-12V	5V
Gnd	Gnd
In1	D1: GPIO 22
In2	D2: GPIO 21
In3	D3: GPIO 17
In4	D4: GPIO 16

A stepper object is created with:

from stepper import steppingMotor 
stepper = steppingMotor() # the parameters p1,p2,p3,p4 are optional and allow to connect the stepping motor to different GPIO lines

The steppingMotor class uses different modes for stepping:

SINGLE_PHASE_FORWARD (default)
SINGLE_PHASE_BACKWARD
DOUBLE_PHASE_FORWARD
DOUBLE_PHASE_BACKWARD
HALF_STEP-FORWARD
HALF_STEP_BACKWARD

You can set the mode with the method stepMode():

stepper.stepMode(stepper.DOUBLE_PHASE_FORWARD)

You can change the movement speed with the method waitAfterSteps() which defines how long to wait after each step in ms. Valid values are 2..1000. Again the method returns the value currently in use if called without a parameter.

The method clrAll() set all coils (IN1..IN4) to zero.

Finally the method move(noOfSteps) moves the stepping motor noOfSteps in the mode and with the speed currently selected.

Uli Raich - 2020-06-25

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