Beginner
10 min

Drive unipolar stepper motors with ULN2003A and ATmega3250

Ideal for projects that require precise control over stepper motors, such as automated machinery, robotics, and precision positioning systems

Stepper 3 Click with EasyAVR PRO v8

Published Mar 15, 2024

Click board™

Stepper 3 Click

Dev. board

EasyAVR PRO v8

Compiler

NECTO Studio

MCU

ATmega3250

High-voltage, high-current Darlington transistor array designed to control the current flow from a supply voltage through the motor coil by activating one of its seven high-power Darlington output stages

A

A

Hardware Overview

How does it work?

Stepper 3 Click is based on the ULN2003A, a high-voltage, high-current Darlington transistor array from Texas Instruments. Motor step progression is performed by alternating the active driver, which sinks the current through the coil connected to the respective driver. The MCU performs the alteration cycle, which controls the driver inputs: a HIGH logic level on the input pin will set the corresponding driver to a LOW logic level, allowing it to sink current. Besides driving a unipolar stepper motor as the primary function, this Click board™ can also be used for driving relays and brushed DC motors

or as the logic buffer for various applications. Combining more than one driver makes it possible to sink more than 500mA. Stepper 3 Click uses four GPIOs to allow the host MCU to control the stepper motor or other mentioned device. Those pins are labeled as INA, INB, INC, and IND. Four output channels from the ULN2203A and a motor power supply are routed to the unpopulated 5-pin header. The motor can be powered over the 5V rail of the mikroBUSTM socket or the external power supply terminal with voltages of 5 – 30V. The selection can be made over the MOTOR PWR jumper. In

addition, the ULN2003As output channels are also routed to the four output LEDs (outA, outB, outC, and outD) for a visual presentation. This Click board™ can be operated only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Stepper 3 Click hardware overview image

Features overview

Development board

EasyAVR PRO v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 8/16-bit AVR® MCUs from Microchip, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over a WiFi network. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, EasyAVR PRO v8 provides a fluid and immersive working experience, allowing access

anywhere and under any circumstances at any time. Each part of the EasyAVR PRO v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via

the USB Type-C (USB-C) connector. Communication options such as USB-UART and USB DEVICE are also included, alongside the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. EasyAVR PRO v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

EasyAVR PRO v8 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

AVR

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

2048

You complete me!

Accessories

The 28BYJ-48 is an adaptable 5VDC stepper motor with a compact design, ideal for various applications. It features four phases, a speed variation ratio of 1/64, and a stride angle of 5.625°/64 steps, allowing precise control. The motor operates at a frequency of 100Hz and has a DC resistance of 50Ω ±7% at 25°C. It boasts an idle in-traction frequency greater than 600Hz and an idle out-traction frequency exceeding 1000Hz, ensuring reliability in different scenarios. With a self-positioning torque and in-traction torque both exceeding 34.3mN.m at 120Hz, the 28BYJ-48 offers robust performance. Its friction torque ranges from 600 to 1200 gf.cm, while the pull-in torque is 300 gf.cm. This motor makes a reliable and efficient choice for your stepper motor needs.

Stepper 3 Click accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Channel A Control Input
PF0
AN
Channel B Control Input
PG0
RST
Channel C Control Input
PG1
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
NC
NC
3.3V
Ground
GND
GND
Channel D Control Input
PB4
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Stepper 3 Click Schematic schematic

Step by step

Project assembly

EasyAVR PRO v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyAVR PRO v8 as your development board.

EasyAVR PRO v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for ATmega6450 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
Board mapper by product7 hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for Stepper 3 Click driver.

Key functions:

  • stepper3_set_step_mode - This function sets the step mode resolution settings in ctx->step_mode

  • stepper3_set_direction - This function sets the motor direction to clockwise or counter-clockwise in ctx->direction

  • stepper3_drive_motor - This function drives the motor for the specific number of steps at the selected speed

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief Stepper 3 Click Example.
 *
 * # Description
 * This example demonstrates the use of the Stepper 3 Click board by driving the 
 * motor in both directions for a desired number of steps.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes the driver and logger.
 *
 * ## Application Task
 * Drives the motor clockwise for 64 full steps and then counter-clockiwse for 128 half
 * steps with 2 seconds delay before changing the direction. All data is being logged on
 * the USB UART where you can track the program flow.
 *
 * @note
 * Step Motor 5v [MIKROE-1530] is a fully compatible stepper motor for this Click board:
 * https://www.mikroe.com/step-motor-5v
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "stepper3.h"

static stepper3_t stepper3;   /**< Stepper 3 Click driver object. */
static log_t logger;    /**< Logger object. */

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    stepper3_cfg_t stepper3_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    stepper3_cfg_setup( &stepper3_cfg );
    STEPPER3_MAP_MIKROBUS( stepper3_cfg, MIKROBUS_1 );
    if ( DIGITAL_OUT_UNSUPPORTED_PIN == stepper3_init( &stepper3, &stepper3_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    log_printf ( &logger, " Move 64 full steps clockwise \r\n\n" );
    stepper3_set_step_mode ( &stepper3, STEPPER3_MODE_FULL_STEP );
    stepper3_set_direction ( &stepper3, STEPPER3_DIR_CW );
    stepper3_drive_motor ( &stepper3, 64, STEPPER3_SPEED_FAST );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );

    log_printf ( &logger, " Move 128 half steps counter-clockwise \r\n\n" );
    stepper3_set_step_mode ( &stepper3, STEPPER3_MODE_HALF_STEP );
    stepper3_set_direction ( &stepper3, STEPPER3_DIR_CCW );
    stepper3_drive_motor ( &stepper3, 128, STEPPER3_SPEED_VERY_FAST );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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