Discover the magic of brushless motor control with MTD6508 and STM32F091RC
Harness the speed, tame the power
Published Feb 26, 2024
Click board™
Brushless 22 Click
Dev Board
Nucleo-64 with STM32F091RC MCU
Compiler
NECTO Studio
MCU
STM32F091RC
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Hardware Overview
How does it work?
Brushless 22 Click is based on the MTD6508, a 3-phase full-wave sensorless driver for brushless DC motors from Microchip Technology. It features a 180° sinusoidal drive, high torque output, and silent drive. CMOS transistors and a synchronous rectification drive type achieve high efficiency and low power consumption. With adaptive features and parameters, the MTD6508 is intended to cover a broad range of motor characteristics, making this Click board™ extremely cost-efficient in fan applications that require low acoustic noise and low mechanical vibration and are highly efficient. This device provides start-up output slew rate and PWM duty cycle control, allowing designers to balance acoustic performance and reliability. The rotational speed of the motor is controlled through the mikroBUS™ PWM signal. When the PWM signal is high, the motor rotates at full speed, and when the PWM signal is low, the MTD6508 outputs are set to a high impedance state, and the motor is stopped. The sinusoidal start-up open-loop phase current amplitude is controlled via the SS pin, routed on the CS pin of the mikroBUS™ socket, which according to its logic state, chooses whether it is defined by the PWM input duty cycle or fixed at 100%. The output
PWM slew rate can be adjusted with the R4 resistor during Start-Up, which is not populated in a default configuration to reduce motor vibration. By default configuration, the output PWM slew rate can be set via the digital potentiometer from Microchip Technology, which establishes communication with the MCU via I2C serial communication. The MCP4661 also allows the choice of the least significant bit (LSB) of its I2C slave address by positioning SMD jumpers labeled as ADDR SEL to an appropriate position marked as 0 and 1. Once the Start-Up open loop is finished, the MTD6508 will automatically switch to a fixed slew rate. When choosing MCP4661 and not R4 for setting the output PWM slew rate, you need to unpopulate the R4 resistor and leave populated R5 and R8. In addition to the output PWM slew rate and its setting method, the user is also given the option of setting the electromechanical coupling coefficient of the motor (also referred to as “motor constant” or “BEMF constant”) via R9 resistor, which is populated in default configuration or by R6 and R7 voltage divider. The MTD6508 defines the BEMF coefficient as the peak value of the phase-to-phase BEMF voltage normalized to the electrical speed of the motor. Choosing MCP4661
and not voltage divider for setting BEMF constant, unpopulate R9 resistor and leave populated R6 and R7. Alongside I2C communication, several GPIO pins connected to the mikroBUS™ socket pins are also used to forward the information to the MCU. The DIR pin, routed on the RST pin of the mikroBUS™ socket, is used to select the direction of motor rotation (clockwise/counterclockwise). The RT pin, routed on the AN pin of the mikroBUS™ socket, adjusts the phase regulation parameters to allow more stability in applications using 3-Phase BLDC motors attached to a light load, while the FG pin routed on the INT pin serves as a rotation speed indicator, gives information about the speed and phase of the motor. With R12 populated, the rotor speed rotation per minute (RPM) has to be multiplied by three because the FG signal frequency will be divided by three. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. 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
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.
2207V-2500kV BLDC Motor is an outrunner brushless DC motor with a kV rating of 2500 and an M5 shaft diameter. It is an excellent solution for fulfilling many functions initially performed by brushed DC motors or in RC drones, racing cars, and much more.
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 via Debug Mode
1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.
2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.
Software Support
Library Description
This library contains API for Brushless 22 Click driver.
Key functions:
brushless22_set_slew_rate_resistance- This function sets the slew rate resistance by configuring the onboard digital potentiometerbrushless22_set_duty_cycle- This function sets the PWM duty cycle in percentages ( Range[ 0..1 ] )brushless22_switch_direction- This function switches the direction by toggling the DIR pin 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 Brushless22 Click example
*
* # Description
* This example demonstrates the use of the Brushless 22 click board by driving the
* motor in both directions at different speeds.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the driver and performs the click default configuration.
*
* ## Application Task
* Controls the motor speed by changing the PWM duty cycle every 500ms.
* The duty cycle ranges from 0% to 100%. At the minimal speed, the motor switches direction.
* Each step will be logged on the USB UART where you can track the program flow.
*
* @author Stefan Filipovic
*
*/
#include "board.h"
#include "log.h"
#include "brushless22.h"
static brushless22_t brushless22;
static log_t logger;
void application_init ( void )
{
log_cfg_t log_cfg; /**< Logger config object. */
brushless22_cfg_t brushless22_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.
brushless22_cfg_setup( &brushless22_cfg );
BRUSHLESS22_MAP_MIKROBUS( brushless22_cfg, MIKROBUS_1 );
if ( PWM_ERROR == brushless22_init( &brushless22, &brushless22_cfg ) )
{
log_error( &logger, " Communication init." );
for ( ; ; );
}
if ( BRUSHLESS22_ERROR == brushless22_default_cfg ( &brushless22 ) )
{
log_error( &logger, " Default configuration." );
for ( ; ; );
}
log_info( &logger, " Application Task " );
}
void application_task ( void )
{
static int8_t duty_cnt = 1;
static int8_t duty_inc = 1;
float duty = duty_cnt / 10.0;
brushless22_set_duty_cycle ( &brushless22, duty );
log_printf( &logger, "> Duty: %d%%\r\n", ( uint16_t )( duty_cnt * 10 ) );
if ( 10 == duty_cnt )
{
duty_inc = -1;
}
else if ( 0 == duty_cnt )
{
duty_inc = 1;
log_printf( &logger, " Switch direction\r\n\n" );
brushless22_switch_direction ( &brushless22 );
}
duty_cnt += duty_inc;
Delay_ms( 500 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
