Tailor-made solution with A4941 and PIC18F57Q43 for exceptional BLDC motor control
Unleash the force of brushless
Published Feb 13, 2024
Click board™
Brushless 5 Click
Dev. board
Curiosity Nano with PIC18F57Q43
Compiler
NECTO Studio
MCU
PIC18F57Q43
Experience smoother and quieter operation with our brushless motor control system, enhancing user comfort and reducing noise in various applications
A
A
Hardware Overview
How does it work?
Brushless 5 Click is based on the A4941, a three-phase sensorless fan driver from Allegro MicroSystems. This IC features a proprietary sensorless BEMF zero-crossing sensing technique, which provides a speed reading via the FG output pin, routed to the INT pin of the mikroBUS™. The BEMF zero-crossing is the point where the voltage of the undriven motor winding (BEMF is short for Back Electromotive Force) crosses the motor center tap (neutral point) voltage. Neutral point voltage can be approximated using an internally generated reference voltage when the used motor does not provide one. BEMF zero-crossing occurs when a pole of the rotor is aligned with a pole of the stator and is used as a positional reference for the commutation controller section of the A4941. When the zero-crossing occurs, an internal signal is set to a HIGH state, while the beginning of the next phase commutation sets this signal to a LOW state. The signal is latched between the states so that commutation transients do not affect it. This provides a robust and accurate position-sensing system. The internal sequencer is used to commutate the phases based on the position feedback. During the startup period, the internal
oscillator provides the phase commutation instead until a valid BEMF positional signal sequence is detected. The current through the coils is maximum at this stage since the PWM signal with a 100% duty cycle is applied during a startup sequence. The Lock Detect feature prevents the motor from locking up or falling out of synchronization while protecting the coils and the IC from overheating. If a valid FG signal is not detected for 2 seconds, the outputs are turned off for 5 seconds. After this time-out, another restart is attempted. An internal peak overcurrent protection is set to about 1A. If the motor drains more than 1A, especially during the startup, the overcurrent protection will be activated, turning off the output stage for about 25µs. This can prevent the startup of some types of motors, so the longest startup delay of 200ms is chosen for this Click board™. The PWM pin is routed to the same pin of the mikroBUS™ and can be used to control the current through the coils. When the HIGH logic level is applied to the PWM input pin, the current from the power supply flows through the coils. No current is running through the coils when the LOW logic level is applied to the PWM
input pin. Applying a PWM signal with a frequency of 15 kHz to 30 kHz will result in a coil current corresponding to the applied PWM's duty cycle. The minimum pulse width is fixed at 6 μs, allowing the minimum speed to be maintained, even when applying PWM signals with a very low duty cycle. Applying a LOW logic level to the PWM pin for more than 500µs will put the device in low power consumption (standby) mode. The power supply for the motor coils is connected via the external two-pole terminal. VBAT+ input is connected to the positive voltage, while the GND input is connected to the power supply's ground. The voltage of the external power supply should stay between 5V and 16V. The most common use is with 12V motors. The BLDC motor coils should be connected to the four-pole output screw terminal. Respective motor phases are connected to the A, B, and C terminal outputs, while the central point of the BLDC motor can be connected to the output labeled as N. IF the used BLDC motor does not have the central (neutral) point output, the neutral point needed for the BEMF sensing will be generated internally.
Features overview
Development board
PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive
mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI
GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.
Microcontroller Overview
MCU Card / MCU
Architecture
PIC
MCU Memory (KB)
128
Silicon Vendor
Microchip
Pin count
48
RAM (Bytes)
8196
You complete me!
Accessories
Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.
Brushless DC (BLDC) Motor with a Hall sensor represents a high-performance motor from the 42BLF motor series. This motor, wired in a star configuration, boasts a Hall Effect angle of 120°, ensuring precise and reliable performance. With a compact motor length of 47mm and a lightweight design tipping the scales at just 0.29kg, this BLDC motor is engineered to meet your needs. Operating flawlessly at a voltage rating of 24VDC and a speed range of 4000 ± 10% RPM, this motor offers consistent and dependable power. It excels in a normal operational temperature range from -20 to +50°C, maintaining efficiency with a rated current of 1.9A. Also, this product seamlessly integrates with all Brushless Click boards™ and those that require BLDC motors with Hall sensors.
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 Curiosity Nano with PIC18F57Q43 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 Brushless 5 Click driver.
Key functions:
brushless5_set_duty_cycle- Generic sets PWM duty cyclebrushless5_pwm_stop- Stop PWM modulebrushless5_pwm_start- Start PWM module
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
* @brief Brushless5 Click example
*
* # Description
* This library contains an API for the Brushless5 Click driver.
* This example showcases how to initialize and use the Brushless 5 click.
* The click has a brushless 5 motor driver which controls the work
* of the motor through the BLDC terminal.
* In order for this example to work a motor and a power supply are needed.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes the GPIO driver and configures the PWM peripheral for
* controlling the speed of the motor.
*
* ## Application Task
* This is an example that demonstrates the use of a Brushless 5 Click board.
* Brushless 5 Click communicates with the register via the PWM interface.
* Increases and decreasing the speed of the motor demonstrate speed control.
* Results are being sent to the Usart Terminal where you can track their changes.
*
* @author Nikola Peric
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "brushless5.h"
// ------------------------------------------------------------------ VARIABLES
static brushless5_t brushless5;
static log_t logger;
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
brushless5_cfg_t cfg;
/**
* 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 ----" );
Delay_ms( 100 );
// Click initialization.
brushless5_cfg_setup( &cfg );
BRUSHLESS5_MAP_MIKROBUS( cfg, MIKROBUS_1 );
brushless5_init( &brushless5, &cfg );
Delay_ms( 100 );
brushless5_set_duty_cycle ( &brushless5, 0.0 );
brushless5_pwm_start( &brushless5 );
log_info( &logger, "---- Application Task ----" );
Delay_ms( 1000 );
}
void application_task ( void )
{
static int8_t duty_cnt = 1;
static int8_t duty_inc = 1;
float duty = duty_cnt / 10.0;
brushless5_set_duty_cycle ( &brushless5, duty );
log_printf( &logger, "Duty: %d%%\r\n", ( uint16_t )( duty_cnt * 10 ) );
Delay_ms( 500 );
if ( 10 == duty_cnt )
{
duty_inc = -1;
log_printf( &logger, " Slowing down... \r\n" );
}
else if ( 0 == duty_cnt )
{
duty_inc = 1;
log_printf( &logger, " Increasing the motor speed... \r\n" );
}
duty_cnt += duty_inc;
Delay_ms( 500 );
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
