Controlling the Speed of a 28BYJ-48 Stepper Motor with a Potentiometer T174
In this tutorial, we’ll show you how to turn a simple potentiometer into a real-time speed controller for the 28BYJ-48 stepper motor using an Arduino. Rather than a fixed, “one-speed†step sequence, you’ll learn how to read an analog knob and translate its position into a variable delay between coil steps—giving you smooth, twist-to-control motion. All the full Arduino sketch is provided below the article; here we’ll focus on the key concepts and code highlights you saw in the video.
When we jump to 02:31 Wiring Explained, you’ll see the straightforward hookup: the 28BYJ-48 driver’s four inputs go to four digital pins on the Arduino, and the potentiometer’s wiper goes to A0 (with its ends tied to 5 V and GND). A second digital pin simply feeds 5 V to the pot, so everything shares a common ground. This five-wire setup gives you both the motor stepping interface and a live analog control signal.
At 05:38 Code Explained, the sketch’s structure becomes clear:
Desired Speed Baseline
A variable
desiredValuerepresents the target seconds per full revolution (e.g. 20 s). A helper function converts that into a maximum delay (N) between individual half-steps—so you can dial in any slowest speed without hard-coding magic numbers.Analog-to-Delay Mapping
Inside
loop(), we readanalogRead(A0)(0–1023) and usemap()to scale it into the range1…Nmilliseconds. That mapped value becomes thedelay()after each step, so turning the pot from minimum to maximum smoothly sweeps the speed from its slowest crawl up to its fastest spin.Half-Step Drive Sequence
Rather than rely on a library, the code defines four arrays—one per coil—encoding an 8-step half-drive pattern. A small helper function
driveStepper(stepIndex)sets the four output pins accordingly, energizing the coils in the correct order for smooth motion.
By organizing the sketch around these pieces—baseline delay computation, real-time mapping, and a clean drive function—you get full analog control in just a few dozen lines of code.
In 12:25 Motor Speed Formula Explained, we break down the math: the 28BYJ-48’s internal gearbox means 2048 half-steps per output revolution. To achieve any RPM, you calculate the total steps per minute and derive a per-step delay. Our calcDelayfromTime() function generalizes this so you can simply pick “10 s per rev,†“20 s per rev,†etc., without re-deriving the math each time.
Finally, at 15:03 Demonstration of speed control, you’ll see how responsive the system feels: twist the pot slowly and the motor inches forward; crank it to maximum and you’ll approach around 60 RPM. The serial monitor even echoes the mapped delay or RPM in real time, so you can confirm the mapping is linear and jitter-free.
All of the code snippets and helper functions mentioned here—calcDelayfromTime(), driveStepper(), the mapping logic, and the half-step arrays—are included in full below. Feel free to copy, tweak your desiredValue, or experiment with different step patterns.
🎬 Video Chapters
00:00 – Start
00:39 – Introduction
02:31 – Wiring Explained
05:38 – Code Explained
12:25 – Motor Speed Formula Explained
15:03 – Demonstration of speed control
/*
* This is Arduino code to control the speed of a 28BYJ-48
* stepper motor with a potentiometer.
*
* Written by Ahmad Shamshiri for Robojax Robojax.com
* on June 30, 2019 at 19:04 in Ajax, Ontario, Canada
Watch the video instruction for this sketch:
https://youtu.be/lrEW8xlSnuY
You can get the wiring diagram from my Arduino Course at Udemy.com
Learn Arduino step by step with all libraries, codes, and wiring diagrams all in one place
visit my course now http://robojax.com/L/?id=62
Watch main stepper motor video: https://youtu.be/Sl2mzXfTwCs
If you found this tutorial helpful, please support me so I can continue creating
content like this.
or make a donation using PayPal http://robojax.com/L/?id=64
If you found this tutorial helpful, please support me so I can continue creating
content like this.
or make a donation using PayPal http://robojax.com/L/?id=64
*
* Code is available at http://robojax.com/learn/arduino
* This code is "AS IS" without warranty or liability. Free to be used as long as you keep this note intact.*
* This code has been downloaded from Robojax.com
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
const int desiredValue = 20;//time in sec for a Revolution
const int dir = 2; // 1 for CW and 2 for CCW
int Pin1 = 10;//IN1 is connected to 10
int Pin2 = 11;//IN2 is connected to 11
int Pin3 = 12;//IN3 is connected to 12
int Pin4 = 13;//IN4 is connected to 13
int potPin = A0;// center pin of pot is connected to this pin
int vcc2 = 2;// additional 5V for potentiometer
int pole1[] ={0,0,0,0, 0,1,1,1, 0};//pole1, 8 step values
int pole2[] ={0,0,0,1, 1,1,0,0, 0};//pole2, 8 step values
int pole3[] ={0,1,1,1, 0,0,0,0, 0};//pole3, 8 step values
int pole4[] ={1,1,0,0, 0,0,0,1, 0};//pole4, 8 step values
int poleStep = 0;
int calcDelayfromTime(int t);
void driveStepper(int c);
int N = calcDelayfromTime(desiredValue);
void setup()
{
pinMode(Pin1, OUTPUT);//define pin for ULN2003 in1
pinMode(Pin2, OUTPUT);//define pin for ULN2003 in2
pinMode(Pin3, OUTPUT);//define pin for ULN2003 in3
pinMode(Pin4, OUTPUT);//define pin for ULN2003 in4
pinMode(vcc2, OUTPUT);//define pin as output for 5V for pot
digitalWrite(vcc2, HIGH);//set vcc2 pin HIGH to have 5V for pot
Serial.begin(9600);
Serial.println("Robojax Stepper Control");
Serial.print("Max time per rev set: ");
Serial.print(desiredValue);
Serial.print(" loop delay: ");
Serial.println(N);
delay(4000);//give use time to read
}// setup
void loop()
{
// Robojax Stepper code S8BYJ-48
if(dir ==1){
poleStep++;
driveStepper(poleStep);
}else if(dir ==2){
poleStep--;
driveStepper(poleStep);
}else{
driveStepper(8);
}
if(poleStep>7){
poleStep=0;
}
if(poleStep<0){
poleStep=7;
}
int potValue =analogRead(potPin);// read potentiometer value
int speed = map(potValue,0, 1023, 1,N);
delay(speed);
}// loop
int calcDelayfromTime(int t){
return ((t-5)/4)+1;
}//
/*
* @brief sends signal to the motor
* @param "c" is an integer representing the pole of the motor
* @return does not return anything
*
* www.Robojax.com code June 2019
*/
void driveStepper(int c)
{
digitalWrite(Pin1, pole1[c]);
digitalWrite(Pin2, pole2[c]);
digitalWrite(Pin3, pole3[c]);
digitalWrite(Pin4, pole4[c]);
}//driveStepper end here资源与参考
文件📁
没有可用的文件。
