Handle the driving of stepper motors with DRV8886 and STM32F091RC
PWM microstepping stepper motor driver with integrated current sense
Published Mar 15, 2024
Click board™
Stepper 6 click
Dev. board
Nucleo-64 with STM32F091RC MCU
Compiler
NECTO Studio
MCU
STM32F091RC
A solution for driving bipolar stepper motors that ensures quiet operation, precise control, and easy setup is ideal for projects requiring reliable performance
A
A
Hardware Overview
How does it work?
Stepper 6 Click is based on the DRV8886, a highly integrated bipolar step motor driver with current sensing from Texas Instruments. This integrated driver offers a simple interface featuring a set of pins used to control the functions of the step motor. Since the number of pins exceeds the available mikroBUS™ general purpose pins, an additional port expander IC is used, exposing a 2-wire I2C interface to communicate with the host MCU. The port expander IC is the PCA9538, an 8-bit port expander with the I2C interface, an interrupt, and a reset from NXP Semiconductor. The high efficiency of the integrated N-Channel power MOSFET H-Bridges allows for high efficiency: Stepper 6 click can withstand peaks of current up to 3A, while the internal current limiter is set to 1.4 A per bridge. The Click board™ can work within the range from 8V up to 35V. However, component heating is expected when operated near the upper current and voltage limits. If the temperature threshold of 150° is reached, thermal protection will be engaged, while the fault condition will be indicated with the default pin of the DRV8886 IC. The nFAULT pin is routed to the port expander IC, allowing its state to be read over the I2C interface. The I2C interface bus of the PCA9538 is routed to the appropriate mikroBUS™ pins (SCA, SDL), allowing the host MCU to control it and read the states of its pins. The PCA9538 is also connected to other pins: M0 and M1 pins are routed to this IC, allowing the microstepping configuration over the I2C interface. These two pins set the microstepping size from 1 to 1/6 of a step. The current through the
coils is indexed and depends on a position, so the angle of 0° will allow 100% of the current to run through the coil, scaling it down to 0% for the 90°. These current values change with the step position, and the microstepping current on an H-Bridge output is a sine function. An additional non-circular half-stepping mode is also available when more torque is required at higher motor RPM. The current in this mode is switched from 0% to 100% with no indexed values in between. One of the key features of the DRV8886 IC is the integration of the sensing resistors, which reduces the design complexity. The current decay through the coil for the circular microstepping modes is controlled by the DRV8886 IC, which offers three different decaying modes: slow decay, slow-mixed decay, and all mixed decay. The correct decay mode is necessary to prevent loss of the current regulation through the coil, which might degrade the efficiency of the stepper motor control. The DECAY pin offers control over the decay mode, and it is routed to the SMD jumper JP3, allowing it to be either pulled up (to the DVDD) or to the GND. The DRV8886 offers detailed information about the decay modes and how to set this pin for each. The maximum current is limited by setting the current through the RREF pin. A DAC converter is used to set the voltage at this pin. The pin is typically used with the resistor connected to the GND, but the Stepper 6 click uses the MCP4921, a dedicated 12-bit DAC with SPI interface, from Microchip. This way, the firmware can change the maximum current limit. The SPI interface of the MCP4921 is routed to the
mikroBUS™, allowing the host MCU to control the maximum current limit. The maximum current is additionally scaled down by the TRQ pin, which can have three different states. A logic LOW state on this pin will not scale the current limit at all. A logic HIGH will scale the current limiting factor down to 50%. If the pin is in the HIGH-Z mode (floating), the current limiting factor will be 75%. The STEP, DIR, and EN pins of the DRV8886 are directly routed to the mikroBUS™ pins AN, PWM, and RST, respectively. These pins comprise the basic stepper motor driving interface, typically used on many similar devices: a rising edge on the STEP input pin will advance the internal sequencer (indexer) for one step; the DIR pin sets the direction, while the EN pin enables the output drives. A LOW logic level on this pin disables the H-Bridges at the output, leaving the logic section operational. A rising edge on the STEP input will still advance the internal sequencer, yet the connected motor will not act, as the H-Bridges are disabled. Stepper 6 click has additional SMD jumpers that are used to set up the I2C slave address for the PCA9538 port expander (JP1 and JP2), as well as the logic voltage level selection SMD jumper, which allows selecting either 3.3V or 5V, allowing interfacing with a wide range of different MCUs. The motor power supply, as well as the two coils of a bipolar stepper motor (A and B), are connected to the Click board™ via the screw terminal block, according to the labeling on the bottom side of the Click board™, beneath the terminal.
Features overview
Development board
Nucleo-64 with STM32F091RC MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M0
MCU Memory (KB)
256
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
32768
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. 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 STM32 Nucleo-64 board with our Click Shield for Nucleo-64, 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 Nucleo-64 with STM32F091RC MCU 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 6 Click driver.
Key functions:
stepper6_set_direction- This function sets the motor direction by setting the DIR pin logic statestepper6_set_step_mode- This function sets the step mode resolution settingsstepper6_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 6 Click example
*
* # Description
* This example demonstrates the use of the Stepper 6 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 200 full steps and then counter-clockiwse for 200 half
* steps and 400 quarter steps with 2 seconds delay on driving mode change. All data is
* being logged on the USB UART where you can track the program flow.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "stepper6.h"
static stepper6_t stepper6;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
stepper6_cfg_t stepper6_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.
stepper6_cfg_setup( &stepper6_cfg );
STEPPER6_MAP_MIKROBUS( stepper6_cfg, MIKROBUS_1 );
err_t init_flag = stepper6_init( &stepper6, &stepper6_cfg );
if ( ( I2C_MASTER_ERROR == init_flag ) || ( SPI_MASTER_ERROR == init_flag ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( STEPPER6_ERROR == stepper6_default_cfg ( &stepper6 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
log_printf ( &logger, " Move 200 full steps clockwise, speed: slow\r\n\n" );
stepper6_set_direction ( &stepper6, STEPPER6_DIR_CW );
stepper6_set_step_mode ( &stepper6, STEPPER6_MODE_FULL_STEP );
stepper6_drive_motor ( &stepper6, 200, STEPPER6_SPEED_SLOW );
Delay_ms ( 2000 );
log_printf ( &logger, " Move 200 half steps counter-clockwise, speed: medium\r\n\n" );
stepper6_set_direction ( &stepper6, STEPPER6_DIR_CCW );
stepper6_set_step_mode ( &stepper6, STEPPER6_MODE_HALF_STEP );
stepper6_drive_motor ( &stepper6, 200, STEPPER6_SPEED_MEDIUM );
Delay_ms ( 2000 );
log_printf ( &logger, " Move 400 quarter steps counter-clockwise, speed: fast\r\n\n" );
stepper6_set_direction ( &stepper6, STEPPER6_DIR_CCW );
stepper6_set_step_mode ( &stepper6, STEPPER6_MODE_QUARTER_STEP );
stepper6_drive_motor ( &stepper6, 400, STEPPER6_SPEED_FAST );
Delay_ms ( 2000 );
}
int main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
return 0;
}
// ------------------------------------------------------------------------ END
