Control stepper motors with A4988 and ATmega2560
Microstepping driver for controlling bipolar stepper motors with a built-in translator for easy operation
Published Mar 05, 2024
Click board™
Stepper 2 Click
Dev. board
Arduino Mega 2560 Rev3
Compiler
NECTO Studio
MCU
ATmega2560
Achieve bidirectional movement of the stepper motors with just two signals, one for controlling the rotation direction and the other for controlling the steps
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Hardware Overview
How does it work?
Stepper 2 Click is based on the A4988, a DMOS micro-stepping driver from Allegro Microsystems. Additional features of the Stepper click include under-voltage, shoot-through, short circuit, overcurrent, and thermal protection so that the Click board™ can operate reliably. Its input voltage range of up to 35V can drive a wide range of stepper motors. This highly integrated IC offers a very simple bipolar stepper motor control interface, thanks to the integrated translator section. This section controls the output drivers, providing smooth action of the stepper motor. By controlling the current intensity and its decay throughout the rotation cycle, a constant torque is achieved for every position. The current regulator uses an internal comparator, DA converter (DAC), and external sensing resistor. The sensing resistor limits the current to about 1.6A (for a reference voltage of 3.3V). The Click board™ is equipped
with the input and output screw terminals. The right terminal connects the external power supply, which should stay within the range from 8V to 35V. The stepper motor can be connected via screw terminals, with their input terminals labeled 1A, 1B, and 2A, 2B. Stepper 2 Click uses the GPIO pins to allow the host MCU to control the motor. A LOW to HIGH transition on the ST pin will perform one rotational step. The logic state on the DIR pin controls the direction of the rotation. The step size is determined by three pins: MS1, M2, and MS3. It is possible to work with five-movement step sizes, ranging from full step size up to sixteenth step size. MS1, MS2, and MS3 pins are routed to the SMD jumpers labeled as STEP MODE (J1, J2, and J3), allowing step size to be selected by moving each of them according to the micro-stepping resolution truth table. This device supports the sleep mode, activated by a LOW logic level on the sleep SL pin.
This will power down the unused sections of the A4988 IC, reducing power consumption to a minimum. After the wake-up event (logic HIGH on the SL pin), at least 1ms of delay is required until the charge pump capacitors are recharged, allowing normal operation of the output stage drivers. The EN pin allows the host MCU to turn ON or OFF the output stage MOSFETs of the A4988 IC. Asserting this pin to a LOW logic level enables the output stage. The RST pin sets DACs and the phase current polarity to the initial Home state. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.
Features overview
Development board
Arduino Mega 2560 is a robust microcontroller platform built around the ATmega 2560 chip. It has extensive capabilities and boasts 54 digital input/output pins, including 15 PWM outputs, 16 analog inputs, and 4 UARTs. With a 16MHz crystal
oscillator ensuring precise timing, it offers seamless connectivity via USB, a convenient power jack, an ICSP header, and a reset button. This all-inclusive board simplifies microcontroller projects; connect it to your computer via USB or power it up
using an AC-to-DC adapter or battery. Notably, the Mega 2560 maintains compatibility with a wide range of shields crafted for the Uno, Duemilanove, or Diecimila boards, ensuring versatility and ease of integration.
Microcontroller Overview
MCU Card / MCU
Architecture
AVR
MCU Memory (KB)
256
Silicon Vendor
Microchip
Pin count
100
RAM (Bytes)
8192
You complete me!
Accessories
Click Shield for Arduino Mega comes equipped with four mikroBUS™ sockets, with two in the form of a Shuttle connector, allowing all the Click board™ devices to be interfaced with the Arduino Mega board with no effort. Featuring an AVR 8-bit microcontroller with advanced RISC architecture, 54 digital I/O pins, and Arduino™ compatibility, the Arduino Mega board offers limitless possibilities for prototyping and creating diverse applications. This board is controlled and powered conveniently through a USB connection to program and debug the Arduino Mega board efficiently out of the box, with an additional USB cable connected to the USB B port on the board. Simplify your project development with the integrated ATmega16U2 programmer and unleash creativity using the extensive I/O options and expansion capabilities. There are eight switches, which you can use as inputs, and eight LEDs, which can be used as outputs of the MEGA2560. In addition, the shield features the MCP1501, a high-precision buffered voltage reference from Microchip. This reference is selected by default over the EXT REF jumper at the bottom of the board. You can choose an external one, as you would usually do with an Arduino Mega board. There is also a GND hook for testing purposes. Four additional LEDs are PWR, LED (standard pin D13), RX, and TX LEDs connected to UART1 (mikroBUS™ 1 socket). This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino Mega board with Click Shield for Arduino Mega, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
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.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Arduino Mega 2560 Rev3 as your development board.
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 2 Click driver.
Key functions:
stepper2_drive_motor- This function drives the motor for the specific number of steps at the selected speedstepper2_set_direction- This function sets the motor direction by setting the DIR pin logic statestepper2_enable_device- This function enables the device by setting the ENABLE pin to low logic state
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 2 Click Example.
*
* # Description
* This example demonstrates the use of the Stepper 2 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 performs the Click default configuration.
*
* ## Application Task
* Drives the motor clockwise for 64 steps and then counter-clockiwse for 32 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 compatible stepper motor for this Click board:
* https://www.mikroe.com/step-motor-5v
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "stepper2.h"
static stepper2_t stepper2; /**< Stepper 2 Click driver object. */
static log_t logger; /**< Logger object. */
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
stepper2_cfg_t stepper2_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.
stepper2_cfg_setup( &stepper2_cfg );
STEPPER2_MAP_MIKROBUS( stepper2_cfg, MIKROBUS_1 );
if ( DIGITAL_OUT_UNSUPPORTED_PIN == stepper2_init( &stepper2, &stepper2_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
stepper2_default_cfg ( &stepper2 );
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
log_printf ( &logger, " Move 64 steps clockwise\r\n\n" );
stepper2_set_direction ( &stepper2, STEPPER2_DIR_CW );
stepper2_drive_motor ( &stepper2, 64, STEPPER2_SPEED_VERY_FAST );
Delay_ms ( 1000 );
Delay_ms ( 1000 );
log_printf ( &logger, " Move 32 steps counter-clockwise\r\n\n" );
stepper2_set_direction ( &stepper2, STEPPER2_DIR_CCW );
stepper2_drive_motor ( &stepper2, 32, STEPPER2_SPEED_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
Category:Stepper
