servo.c

#include <stdio.h>

#include "stm32f4xx_hal.h"

#include "nlr.h"
#include "misc.h"
#include "mpconfig.h"
#include "qstr.h"
#include "obj.h"
#include "runtime.h"
#include "timer.h"
#include "servo.h"

// this servo driver uses hardware PWM to drive servos on PA0, PA1, PA2, PA3 = X1, X2, X3, X4
// TIM2 and TIM5 have CH1, CH2, CH3, CH4 on PA0-PA3 respectively
// they are both 32-bit counters with 16-bit prescaler
// we use TIM5

#define PYB_SERVO_NUM (4)

typedef struct _pyb_servo_obj_t {
    mp_obj_base_t base;
    uint8_t servo_id;
    uint8_t pulse_min;          // units of 10us
    uint8_t pulse_max;          // units of 10us
    uint8_t pulse_centre;       // units of 10us
    uint8_t pulse_angle_90;     // units of 10us; pulse at 90 degrees, minus pulse_centre
    uint8_t pulse_speed_100;    // units of 10us; pulse at 100% forward speed, minus pulse_centre
    uint16_t pulse_cur;         // units of 10us
    uint16_t pulse_dest;        // units of 10us
    int16_t pulse_accum;
    uint16_t time_left;
} pyb_servo_obj_t;

STATIC pyb_servo_obj_t pyb_servo_obj[PYB_SERVO_NUM];

void servo_init(void) {
    timer_tim5_init();

    // reset servo objects
    for (int i = 0; i < PYB_SERVO_NUM; i++) {
        pyb_servo_obj[i].base.type = &pyb_servo_type;
        pyb_servo_obj[i].servo_id = i + 1;
        pyb_servo_obj[i].pulse_min = 64;
        pyb_servo_obj[i].pulse_max = 242;
        pyb_servo_obj[i].pulse_centre = 150;
        pyb_servo_obj[i].pulse_angle_90 = 97;
        pyb_servo_obj[i].pulse_speed_100 = 70;
        pyb_servo_obj[i].pulse_cur = 150;
        pyb_servo_obj[i].pulse_dest = 0;
        pyb_servo_obj[i].time_left = 0;
    }
}

void servo_timer_irq_callback(void) {
    bool need_it = false;
    for (int i = 0; i < PYB_SERVO_NUM; i++) {
        pyb_servo_obj_t *s = &pyb_servo_obj[i];
        if (s->pulse_cur != s->pulse_dest) {
            // clamp pulse to within min/max
            if (s->pulse_dest < s->pulse_min) {
                s->pulse_dest = s->pulse_min;
            } else if (s->pulse_dest > s->pulse_max) {
                s->pulse_dest = s->pulse_max;
            }
            // adjust cur to get closer to dest
            if (s->time_left <= 1) {
                s->pulse_cur = s->pulse_dest;
                s->time_left = 0;
            } else {
                s->pulse_accum += s->pulse_dest - s->pulse_cur;
                s->pulse_cur += s->pulse_accum / s->time_left;
                s->pulse_accum %= s->time_left;
                s->time_left--;
                need_it = true;
            }
            // set the pulse width
            switch (s->servo_id) {
                case 1: TIM5->CCR1 = s->pulse_cur; break;
                case 2: TIM5->CCR2 = s->pulse_cur; break;
                case 3: TIM5->CCR3 = s->pulse_cur; break;
                case 4: TIM5->CCR4 = s->pulse_cur; break;
            }
        }
    }
    if (need_it) {
        __HAL_TIM_ENABLE_IT(&TIM5_Handle, TIM_IT_UPDATE);
    } else {
        __HAL_TIM_DISABLE_IT(&TIM5_Handle, TIM_IT_UPDATE);
    }
}

STATIC void servo_init_channel(pyb_servo_obj_t *s) {
    uint32_t pin;
    uint32_t channel;
    switch (s->servo_id) {
        case 1: pin = GPIO_PIN_0; channel = TIM_CHANNEL_1; break;
        case 2: pin = GPIO_PIN_1; channel = TIM_CHANNEL_2; break;
        case 3: pin = GPIO_PIN_2; channel = TIM_CHANNEL_3; break;
        case 4: pin = GPIO_PIN_3; channel = TIM_CHANNEL_4; break;
        default: return;
    }

    // GPIO configuration
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.Pin = pin;
    GPIO_InitStructure.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStructure.Speed = GPIO_SPEED_FAST;
    GPIO_InitStructure.Pull = GPIO_NOPULL;
    GPIO_InitStructure.Alternate = GPIO_AF2_TIM5;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStructure);

    // PWM mode configuration
    TIM_OC_InitTypeDef oc_init;
    oc_init.OCMode = TIM_OCMODE_PWM1;
    oc_init.Pulse = s->pulse_cur; // units of 10us
    oc_init.OCPolarity = TIM_OCPOLARITY_HIGH;
    oc_init.OCFastMode = TIM_OCFAST_DISABLE;
    HAL_TIM_PWM_ConfigChannel(&TIM5_Handle, &oc_init, channel);

    // start PWM
    HAL_TIM_PWM_Start(&TIM5_Handle, channel);
}

/******************************************************************************/
// Micro Python bindings

STATIC mp_obj_t pyb_servo_set(mp_obj_t port, mp_obj_t value) {
    int p = mp_obj_get_int(port);
    int v = mp_obj_get_int(value);
    if (v < 50) { v = 50; }
    if (v > 250) { v = 250; }
    switch (p) {
        case 1: TIM5->CCR1 = v; break;
        case 2: TIM5->CCR2 = v; break;
        case 3: TIM5->CCR3 = v; break;
        case 4: TIM5->CCR4 = v; break;
    }
    return mp_const_none;
}

MP_DEFINE_CONST_FUN_OBJ_2(pyb_servo_set_obj, pyb_servo_set);

STATIC mp_obj_t pyb_pwm_set(mp_obj_t period, mp_obj_t pulse) {
    int pe = mp_obj_get_int(period);
    int pu = mp_obj_get_int(pulse);
    TIM5->ARR = pe;
    TIM5->CCR3 = pu;
    return mp_const_none;
}

MP_DEFINE_CONST_FUN_OBJ_2(pyb_pwm_set_obj, pyb_pwm_set);

STATIC void pyb_servo_print(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t self_in, mp_print_kind_t kind) {
    pyb_servo_obj_t *self = self_in;
    print(env, "<Servo %lu at %luus>", self->servo_id, 10 * self->pulse_cur);
}

STATIC mp_obj_t pyb_servo_make_new(mp_obj_t type_in, uint n_args, uint n_kw, const mp_obj_t *args) {
    // check arguments
    mp_arg_check_num(n_args, n_kw, 1, 1, false);

    // get servo number
    machine_int_t servo_id = mp_obj_get_int(args[0]) - 1;

    // check servo number
    if (!(0 <= servo_id && servo_id < PYB_SERVO_NUM)) {
        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "Servo %d does not exist", servo_id + 1));
    }

    // get and init servo object
    pyb_servo_obj_t *s = &pyb_servo_obj[servo_id];
    s->pulse_dest = s->pulse_cur;
    s->time_left = 0;
    servo_init_channel(s);

    return s;
}

STATIC mp_obj_t pyb_servo_pulse_width(uint n_args, const mp_obj_t *args) {
    pyb_servo_obj_t *self = args[0];
    if (n_args == 1) {
        // get pulse width, in us
        return mp_obj_new_int(10 * self->pulse_cur);
    } else {
        // set pulse width, in us
        self->pulse_dest = mp_obj_get_int(args[1]) / 10;
        self->time_left = 0;
        servo_timer_irq_callback();
        return mp_const_none;
    }
}

STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_servo_pulse_width_obj, 1, 2, pyb_servo_pulse_width);

STATIC mp_obj_t pyb_servo_calibration(uint n_args, const mp_obj_t *args) {
    pyb_servo_obj_t *self = args[0];
    if (n_args == 1) {
        // get calibration values
        mp_obj_t tuple[5];
        tuple[0] = mp_obj_new_int(10 * self->pulse_min);
        tuple[1] = mp_obj_new_int(10 * self->pulse_max);
        tuple[2] = mp_obj_new_int(10 * self->pulse_centre);
        tuple[3] = mp_obj_new_int(10 * (self->pulse_angle_90 + self->pulse_centre));
        tuple[4] = mp_obj_new_int(10 * (self->pulse_speed_100 + self->pulse_centre));
        return mp_obj_new_tuple(5, tuple);
    } else if (n_args >= 4) {
        // set min, max, centre
        self->pulse_min = mp_obj_get_int(args[1]) / 10;
        self->pulse_max = mp_obj_get_int(args[2]) / 10;
        self->pulse_centre = mp_obj_get_int(args[3]) / 10;
        if (n_args == 4) {
            return mp_const_none;
        } else if (n_args == 6) {
            self->pulse_angle_90 = mp_obj_get_int(args[4]) / 10 - self->pulse_centre;
            self->pulse_speed_100 = mp_obj_get_int(args[5]) / 10 - self->pulse_centre;
            return mp_const_none;
        }
    }

    // bad number of arguments
    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "calibration expecting 1, 4 or 6 arguments, got %d", n_args));
}

STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_servo_calibration_obj, 1, 6, pyb_servo_calibration);

STATIC mp_obj_t pyb_servo_angle(uint n_args, const mp_obj_t *args) {
    pyb_servo_obj_t *self = args[0];
    if (n_args == 1) {
        // get angle
        return mp_obj_new_int((self->pulse_cur - self->pulse_centre) * 90 / self->pulse_angle_90);
    } else {
#if MICROPY_ENABLE_FLOAT
        self->pulse_dest = self->pulse_centre + self->pulse_angle_90 * mp_obj_get_float(args[1]) / 90.0;
#else
        self->pulse_dest = self->pulse_centre + self->pulse_angle_90 * mp_obj_get_int(args[1]) / 90;
#endif
        if (n_args == 2) {
            // set angle immediately
            self->time_left = 0;
        } else {
            // set angle over a given time (given in milli seconds)
            self->time_left = mp_obj_get_int(args[2]) / 20;
            self->pulse_accum = 0;
        }
        servo_timer_irq_callback();
        return mp_const_none;
    }
}

STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_servo_angle_obj, 1, 3, pyb_servo_angle);

STATIC mp_obj_t pyb_servo_speed(uint n_args, const mp_obj_t *args) {
    pyb_servo_obj_t *self = args[0];
    if (n_args == 1) {
        // get speed
        return mp_obj_new_int((self->pulse_cur - self->pulse_centre) * 100 / self->pulse_speed_100);
    } else {
#if MICROPY_ENABLE_FLOAT
        self->pulse_dest = self->pulse_centre + self->pulse_speed_100 * mp_obj_get_float(args[1]) / 100.0;
#else
        self->pulse_dest = self->pulse_centre + self->pulse_speed_100 * mp_obj_get_int(args[1]) / 100;
#endif
        if (n_args == 2) {
            // set speed immediately
            self->time_left = 0;
        } else {
            // set speed over a given time (given in milli seconds)
            self->time_left = mp_obj_get_int(args[2]) / 20;
            self->pulse_accum = 0;
        }
        servo_timer_irq_callback();
        return mp_const_none;
    }
}

STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(pyb_servo_speed_obj, 1, 3, pyb_servo_speed);

STATIC const mp_map_elem_t pyb_servo_locals_dict_table[] = {
    { MP_OBJ_NEW_QSTR(MP_QSTR_pulse_width), (mp_obj_t)&pyb_servo_pulse_width_obj },
    { MP_OBJ_NEW_QSTR(MP_QSTR_calibration), (mp_obj_t)&pyb_servo_calibration_obj },
    { MP_OBJ_NEW_QSTR(MP_QSTR_angle), (mp_obj_t)&pyb_servo_angle_obj },
    { MP_OBJ_NEW_QSTR(MP_QSTR_speed), (mp_obj_t)&pyb_servo_speed_obj },
};

STATIC MP_DEFINE_CONST_DICT(pyb_servo_locals_dict, pyb_servo_locals_dict_table);

const mp_obj_type_t pyb_servo_type = {
    { &mp_type_type },
    .name = MP_QSTR_Servo,
    .print = pyb_servo_print,
    .make_new = pyb_servo_make_new,
    .locals_dict = (mp_obj_t)&pyb_servo_locals_dict,
};