April 9, 2024

Implementing a Simple Stepper Motor Control with AVR Atmega-328

Stepper motors are widely used in various applications ranging from robotics, CNC machines, 3D printers, to automation systems. These motors provide precise control over position and speed, making them suitable for projects requiring accurate motion control.

In this blog post, we will explore how to implement a simple stepper motor control using the AVR Atmega-328 microcontroller. We will dive into the necessary components, circuitry, code, and explanations. So, let’s get started!

Components Required

To begin, let’s gather the required components for our project:

1. AVR Atmega-328 microcontroller
2. Stepper motor
3. ULN2003A stepper motor driver
4. Breadboard and jumper wires

Circuit Setup

The ULN2003A is a popular and simple stepper motor driver that can be easily interfaced with microcontrollers. It provides the necessary current and voltage amplification to drive the stepper motor. Here’s how to set up the circuit:

1. Connect the VCC and GND pins of the ULN2003A to the +5V and GND respectively on the Atmega-328.
2. Connect pins IN1, IN2, IN3, and IN4 of the ULN2003A to digital pins 8, 9, 10, and 11 on the Atmega-328 respectively.
3. Connect the stepper motor to the ULN2003A as per the datasheet specifications.

Make sure to double-check all connections and refer to the datasheets for pin configurations of the stepper motor and the ULN2003A.

Stepper Motor Control Code

Now that our circuitry is set up, let’s dive into the code. We will program the Atmega-328 microcontroller in C using the AVR-GCC compiler. Here’s an example code to rotate the stepper motor in one direction:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

#include <avr/io.h>
#include <util/delay.h>

int main(void) {
  // Configure pins as outputs
  DDRB |= (1 << PB0) | (1 << PB1) | (1 << PB2) | (1 << PB3);

  // Define the stepping sequence
  unsigned char sequence[] = {0x01, 0x02, 0x04, 0x08};

  // Number of steps and delay between steps
  int numSteps = 2048;
  int delay_ms = 2;

  // Step the motor in one direction
  for (int i = 0; i < numSteps; i++) {
    for (int j = 0; j < 4; j++) {
      PORTB = sequence[j];
      _delay_ms(delay_ms);
    }
  }

  return 0;
}

In the code above, we first configure the digital pins connected to the ULN2003A outputs as outputs using the DDRB register. We then define a stepping sequence that determines the coil energization pattern. In this example, we use a full-step sequence.

Next, we set the number of steps and the delay between each step. These values determine the speed and rotation angle of the stepper motor. Adjusting these parameters allows you to control the motor’s behavior precisely.

Finally, we loop through the stepping sequence for the desired number of steps, setting the corresponding outputs of the ULN2003A using the PORTB register, and adding a delay between steps to achieve smooth movement.

Conclusion

In this blog post, we explored how to implement a simple stepper motor control using the AVR Atmega-328 microcontroller. We covered the necessary components, circuit setup, and provided an example code snippet.

Remember that stepper motors require proper current and voltage matching while connecting to the microcontroller. Always consult the datasheets of the motor, driver, and microcontroller to ensure correct interfacing.

This implementation is just scratching the surface of what you can do with stepper motors. You can expand upon this project by adding sensor inputs, implementing acceleration profiles, or even incorporating microstepping for smoother motion.

So, go ahead and experiment with stepper motors to enhance your projects' precision and control. Happy coding!

➡️ A primer on Jinja2

⬅️ Guides on learning Rust

Go back to Posts.