Getting to know the SimpleFOClibrary code

Once when you have your SimpleFOClibrary installed and you have all the necessary hardware, we can finally start to get to know with the Arduino code that will run your motor. Here are all the most important steps when writing the code!

Step 0. Include the library

Let’s start by including the library header file:

#include <SimpleFOC.h>

Step 1. Position sensor setup

First step when writing the code is initializing and configuring the position sensor. The library supports these position sensors:

• Encoders: Optical, Capacitive, Magnetic encoders (ABI)
• Magnetic sensors: SPI, I2C, Analog or PWM
• Hall sensors: 3xHall sonde, Magnetic sensor (UVW interface)

Choose position sensor to use with this example:

Magnetic sensor Encoder

#include <SimpleFOC.h>

// Encoder(pin_A, pin_B, PPR)
Encoder sensor = Encoder(2, 3, 2048);
// channel A and B callbacks
void doA(){sensor.handleA();}
void doB(){sensor.handleB();}

 
void setup() {  
  // initialize encoder hardware
  sensor.init();
  // hardware interrupt enable
  sensor.enableInterrupts(doA, doB);

}

void loop() {
  
}

#include <SimpleFOC.h>

// SPI example
// MagneticSensorSPI(int cs, float bit_resolution, int angle_register)
MagneticSensorSPI sensor = MagneticSensorSPI(10, 14, 0x3FFF);

void setup() {
  // initialize magnetic sensor hardware
  sensor.init();
}

void loop() {

}

Sensor is initialized hardware pins by running sensor.init().

For full documentation of the setup and all configuration parameters please visit the position sensors docs .

Step 2. Driver setup

After the position sensor we proceed to initializing and configuring the driver. The library supports BLDC drivers handled by BLDCDriver3PWM and BLDCDriver6PWM classes as well as the stepper drivers handled by StepperDriver4PWM class.

BLDCDriver3PWM class instantiated by providing:

• phase A, B and C pin number
• enable pin number (optional)

For example:

#include <SimpleFOC.h>

//  BLDCDriver3PWM( pin_pwmA, pin_pwmB, pin_pwmC, enable (optional))
BLDCDriver3PWM driver = BLDCDriver3PWM(9, 5, 6, 8);

// instantiate sensor 

void setup() {  

  // init sensor

  // power supply voltage
  driver.voltage_power_supply = 12;
  // driver init
  driver.init();

}

void loop() {

}

For full documentation of the setup and all configuration parameters please visit the driver docs .

Step 3. Current sense setup

After the position sensor and the driver we can proceed to initializing and configuring the current sense, if available of course. If current sense is not available you can skip this step. The library supports two types of current sense architecture:

• in-line current sensing InlineCurrentSense.
• low-side current sensing LowsideCurrentSense.

InlineCurrentSense and LowsideCurrentSense classes are instantiated by providing:

• shunt resistor value shunt_resistance
• amplifier gain gain
• `phase A, B (and optionally C) pin number

For example:

#include <SimpleFOC.h>

// instantiate driver
// instantiate sensor

//  InlineCurrentSense(shunt_resistance, gain, adc_a, adc_b)
InlineCurrentSense current_sense = InlineCurrentSense(0.01, 50, A0, A2);


void setup() {  

  // init sensor

  // init driver

  // init current sense
  current_sense.init();

}

void loop() {

}

For full documentation of the setup and all configuration parameters please visit the current sense docs .

Step 4. Motor setup

After the position sensor and the driver we proceed to initializing and configuring the motor. The library supports BLDC motors handled by BLDCMotor class as well as the stepper motors handled by StepperMotor class. Both classes are instantiated by providing just the pole_pairs number of the motor

// StepperMotor(int pole_pairs)
StepperMotor motor = StepperMotor(50);

// BLDCMotor(int pole_pairs)
BLDCMotor motor = BLDCMotor(11);

In this example we will use BLDC motor:

#include <SimpleFOC.h>

//  BLDCMotor( int pole_pairs )
BLDCMotor motor = BLDCMotor( 11);
 
// instantiate driver
// instantiate sensor 
// instantiate current sensor   

void setup() {  
  // init sensor
  // link the motor to the sensor
  motor.linkSensor(&sensor);

  // init driver
  // link the motor to the driver
  motor.linkDriver(&driver);
  
  // init current sense
  // link to the motor
  motor.linkCurrentSense(&current_sese);

  // set control loop type to be used
  motor.controller = MotionControlType::velocity;
  // initialize motor
  motor.init();

}

void loop() {

}

After the instance of the motor motor has been created we need to link the motor with the sensor motor.linkSensor() and link the motor class to the driver it is connected to motor.linkDriver().
The next step is the configuration step, for the sake of this example we will configure only the motion control loop we will be using:

// set control loop type to be used
motor.controller = MotionControlType::velocity;

And to finish the motor setup we run the motor.init() function.

For full documentation of the setup and all configuration parameters please visit the motor docs .

Step 5. FOC routine and real-time motion control

Once when we have initialized the position sensor, driver and the motor, and before we can run the FOC algorithm we need to align the motor and sensor. This is done by calling motor.initFOC(). After this step we have a functional position sensor, we have configured motor and our FOC algorithm knows how to set the appropriate voltages based on position sensor measurements.

For the real-time routine of the FOC algorithm we need to add the motor.loopFOC() and motor.move(target) functions in the Arduino loop().

• motor.loopFOC(): FOC algorithm execution - should be executed as fast as possible > 1kHz
• motor.move(target): motion control routine - depends of the motor.controller parameter

Here is how it looks in code:

#include <SimpleFOC.h>

// instantiate motor
// instantiate driver
// instantiate sensor 
// instantiate current sensor   

void setup() {  
  
  // init sensor
  // link motor and sensor

  // init driver
  // link motor and driver

  // init current sense
  // link motor and current sense

  // configure motor
  // init motor

  // align encoder and start FOC
  motor.initFOC();
}

void loop() {
  // FOC algorithm function
  motor.loopFOC();

  // velocity control loop function
  // setting the target velocity or 2rad/s
  motor.move(2);
}

For full documentation of the setup and all configuration parameters for BLDC motors please visit the BLDCMotor docs , and for Stepper motors please visit the StepperMotor docs

Step 6. Monitoring

BLDCMotor and StepperMotor classes provide monitoring functionality. For enabling the monitoring feature make sure you call motor.useMonitoring() with the Serial port instance you want to output to. It uses Serial class to output motor initialization status during the motor.init() function, as well as in motor.initFOC() function.

If you are interested to output motors state variables in real-time (even though it will impact the performance - writing the Serial port is slow!) add the motor.monitor() function call to the Arduino loop() function.

#include <SimpleFOC.h>

// instantiate motor
// instantiate driver
// instantiate senor

void setup() {  
  
  // init sensor
  // link motor and sensor

  // init driver
  // link motor and driver

  // init current sense
  // link motor and current sense

  // use monitoring with the BLDCMotor
  Serial.begin(115200);
  // monitoring port
  motor.useMonitoring(Serial);
  
  // configure motor
  // init motor
  
  // align encoder and start FOC
}

void loop() {
  
  // FOC execution
  // motion control loop

  // monitoring function outputting motor variables to the serial terminal 
  motor.monitor();
}

For full documentation of the setup and all configuration parameters please visit the Monitoring docs.

Step 7. Commander Interface

Finally in order to configure the control algorithm, set the target values and get the state variables in the user-friendly way (not just dumping as using motor.monitor()) Arduino SimpleFOClibrary provides you with the g-code like communication interface in a form of Commander class.

The following code is one basic implementations of the full communication interface with the user:

#include <SimpleFOC.h>

// instantiate motor
// instantiate senor

//instantiate commander
Commander commander = Commander(Serial);
void doMotor(char* cmd){commander.motor(&motor, cmd);}

void setup() {  
  
  // init sensor
  // link motor and sensor

  // init driver
  // link motor and driver

  // init current sense
  // link motor and current sense
  
  // enable monitoring
  
  // subscribe motor to the commands
  commander.add('M',doMotor,"motor");

  // init motor
  
  // align encoder and start FOC
}

void loop() {
  
  // FOC execution
  // motion control loop
  // monitor variables

  // read user commands
  commander.run();
}

For full documentation of the setup and all configuration parameters please visit the Communication docs.

Step 8. Getting started step by step guide

Now when you are familiar with the structure of the SimpleFOClibrary code you can finally start writing your own application. In order to make this step less complicated we have provided you a detailed step by step guide. Make sure to go through our step by step getting started guide when first time dealing with the library.

🎨 Full Arduino code of the example

Now when you have learned what are all the parts of the Arduino program and what are they for, here is the full code example with some additional configuration. Please go through the code to better understand how to integrate all previously introduced parts together. This is the code of the library example motor_full_control_serial_examples/magnetic_sensor/full_control_serial.ino.

#include <SimpleFOC.h>

// magnetic sensor instance - SPI
MagneticSensorSPI sensor = MagneticSensorSPI(AS5147_SPI, 10);

// BLDC motor & driver instance
BLDCMotor motor = BLDCMotor(11);
BLDCDriver3PWM driver = BLDCDriver3PWM(9, 5, 6, 8);

// commander interface
Commander command = Commander(Serial);
void onMotor(char* cmd){ command.motor(&motor, cmd); }

void setup() {

  // initialise magnetic sensor hardware
  sensor.init();
  // link the motor to the sensor
  motor.linkSensor(&sensor);

  // driver config
  // power supply voltage [V]
  driver.voltage_power_supply = 12;
  driver.init();
  // link driver
  motor.linkDriver(&driver);

  // set control loop type to be used
  motor.controller = MotionControlType::torque;

  // contoller configuration based on the control type 
  motor.PID_velocity.P = 0.2;
  motor.PID_velocity.I = 20;
  motor.PID_velocity.D = 0;
  // default voltage_power_supply
  motor.voltage_limit = 12;

  // velocity low pass filtering time constant
  motor.LPF_velocity.Tf = 0.01;

  // angle loop controller
  motor.P_angle.P = 20;
  // angle loop velocity limit
  motor.velocity_limit = 50;

  // use monitoring with serial for motor init
  // monitoring port
  Serial.begin(115200);
  // comment out if not needed
  motor.useMonitoring(Serial);

  // initialise motor
  motor.init();
  // align encoder and start FOC
  motor.initFOC();

  // set the inital target value
  motor.target = 2;

  // define the motor id
  command.add('A', onMotor, "motor");

  // Run user commands to configure and the motor (find the full command list in docs.simplefoc.com)
  Serial.println(F("Motor commands sketch | Initial motion control > torque/voltage : target 2V."));
  
  _delay(1000);
}


void loop() {
  // iterative setting FOC phase voltage
  motor.loopFOC();

  // iterative function setting the outter loop target
  // velocity, position or voltage
  // if tatget not set in parameter uses motor.target variable
  motor.move();
  
  // user communication
  command.run();
}

Library source code

If you are interested in extending and adapting the SimpleFOClibrary source code you can find full documentation on library source docs