main_servo.cpp

#include "mbed.h"

// pes board pin map
#include "PESBoardPinMap.h"

// drivers
#include "DebounceIn.h"
#include "Servo.h"

bool do_execute_main_task = false; // this variable will be toggled via the user button (blue button) and
                                   // decides whether to execute the main task or not
bool do_reset_all_once = false;    // this variable is used to reset certain variables and objects and
                                   // shows how you can run a code segment only once

// objects for user button (blue button) handling on nucleo board
DebounceIn user_button(BUTTON1);   // create DebounceIn to evaluate the user button
void toggle_do_execute_main_fcn(); // custom function which is getting executed when user
                                   // button gets pressed, definition at the end

// main runs as an own thread
int main()
{
    // attach button fall function address to user button object
    user_button.fall(&toggle_do_execute_main_fcn);

    // while loop gets executed every main_task_period_ms milliseconds, this is a
    // simple approach to repeatedly execute main
    const int main_task_period_ms = 20; // define main task period time in ms e.g. 20 ms, therefore
                                        // the main task will run 50 times per second
    Timer main_task_timer;              // create Timer object which we use to run the main task
                                        // every main_task_period_ms

    // led on nucleo board
    DigitalOut user_led(LED1);

    // additional led
    // create DigitalOut object to command extra led, you need to add an additional resistor, e.g. 220...500 Ohm
    // a led has an anode (+) and a cathode (-), the cathode needs to be connected to ground via the resistor
    DigitalOut led1(PB_9);

    // --- adding variables and objects and applying functions starts here ---

    // servo
    Servo servo_D0(PB_D0);
    Servo servo_D1(PB_D1);

    // minimal pulse width and maximal pulse width obtained from the servo calibration process
    // futuba S3001
    float servo_D0_ang_min = 0.0150f; // carefull, these values might differ from servo to servo
    float servo_D0_ang_max = 0.1150f;
    // reely S0090
    float servo_D1_ang_min = 0.0325f;
    float servo_D1_ang_max = 0.1175f;

    // servo.setPulseWidth: before calibration (0,1) -> (min pwm, max pwm)
    // servo.setPulseWidth: after calibration (0,1) -> (servo_D0_ang_min, servo_D0_ang_max)
    servo_D0.calibratePulseMinMax(servo_D0_ang_min, servo_D0_ang_max);
    servo_D1.calibratePulseMinMax(servo_D1_ang_min, servo_D1_ang_max);

    // default acceleration of the servo motion profile is 1.0e6f
    servo_D0.setMaxAcceleration(0.3f);
    servo_D1.setMaxAcceleration(0.3f);

    // variables to move the servo, this is just an example
    float servo_input = 0.0f;
    int servo_counter = 0; // define servo counter, this is an additional variable
                           // used to command the servo
    const int loops_per_seconds = static_cast<int>(ceilf(1.0f / (0.001f * static_cast<float>(main_task_period_ms))));

    // start timer
    main_task_timer.start();

    // this loop will run forever
    while (true) {
        main_task_timer.reset();

        // --- code that runs every cycle at the start goes here ---

        if (do_execute_main_task) {

            // --- code that runs when the blue button was pressed goes here ---

            // visual feedback that the main task is executed, setting this once would actually be enough
            led1 = 1;

            // enable the servos
            if (!servo_D0.isEnabled())
                servo_D0.enable();
            if (!servo_D1.isEnabled())
                servo_D1.enable();

            // command the servos
            servo_D0.setPulseWidth(servo_input);
            servo_D1.setPulseWidth(servo_input);

            // calculate inputs for the servos for the next cycle
            if ((servo_input < 1.0f) &&                     // constrain servo_input to be < 1.0f
                (servo_counter % loops_per_seconds == 0) && // true if servo_counter is a multiple of loops_per_second
                (servo_counter != 0))                       // avoid servo_counter = 0
                servo_input += 0.005f;
            servo_counter++;
        } else {
            // the following code block gets executed only once
            if (do_reset_all_once) {
                do_reset_all_once = false;

                // --- variables and objects that should be reset go here ---

                // reset variables and objects
                led1 = 0;
                servo_D0.disable();
                servo_D1.disable();
                servo_input = 0.0f;
            }
        }

        // toggling the user led
        user_led = !user_led;

        // --- code that runs every cycle at the end goes here ---

        // print to the serial terminal
        printf("Pulse width: %f \n", servo_input);

        // read timer and make the main thread sleep for the remaining time span (non blocking)
        int main_task_elapsed_time_ms = duration_cast<milliseconds>(main_task_timer.elapsed_time()).count();
        if (main_task_period_ms - main_task_elapsed_time_ms < 0)
            printf("Warning: Main task took longer than main_task_period_ms\n");
        else
            thread_sleep_for(main_task_period_ms - main_task_elapsed_time_ms);
    }
}

void toggle_do_execute_main_fcn()
{
    // toggle do_execute_main_task if the button was pressed
    do_execute_main_task = !do_execute_main_task;
    // set do_reset_all_once to true if do_execute_main_task changed from false to true
    if (do_execute_main_task)
        do_reset_all_once = true;
}