micropython/ports/rp2/machine_pwm.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2020-2021 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "py/runtime.h"
#include "py/mphal.h"
#include "modmachine.h"

#include "hardware/clocks.h"
#include "hardware/pwm.h"

/******************************************************************************/
// MicroPython bindings for machine.PWM

const mp_obj_type_t machine_pwm_type;

typedef struct _machine_pwm_obj_t {
    mp_obj_base_t base;
    uint8_t slice;
    uint8_t channel;
} machine_pwm_obj_t;

STATIC machine_pwm_obj_t machine_pwm_obj[] = {
    {{&machine_pwm_type}, 0, PWM_CHAN_A},
    {{&machine_pwm_type}, 0, PWM_CHAN_B},
    {{&machine_pwm_type}, 1, PWM_CHAN_A},
    {{&machine_pwm_type}, 1, PWM_CHAN_B},
    {{&machine_pwm_type}, 2, PWM_CHAN_A},
    {{&machine_pwm_type}, 2, PWM_CHAN_B},
    {{&machine_pwm_type}, 3, PWM_CHAN_A},
    {{&machine_pwm_type}, 3, PWM_CHAN_B},
    {{&machine_pwm_type}, 4, PWM_CHAN_A},
    {{&machine_pwm_type}, 4, PWM_CHAN_B},
    {{&machine_pwm_type}, 5, PWM_CHAN_A},
    {{&machine_pwm_type}, 5, PWM_CHAN_B},
    {{&machine_pwm_type}, 6, PWM_CHAN_A},
    {{&machine_pwm_type}, 6, PWM_CHAN_B},
    {{&machine_pwm_type}, 7, PWM_CHAN_A},
    {{&machine_pwm_type}, 7, PWM_CHAN_B},
};

STATIC void machine_pwm_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    machine_pwm_obj_t *self = MP_OBJ_TO_PTR(self_in);
    mp_printf(print, "<PWM slice=%u channel=%u>", self->slice, self->channel);
}

// PWM(pin)
STATIC mp_obj_t machine_pwm_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
    // Check number of arguments
    mp_arg_check_num(n_args, n_kw, 1, 1, false);

    // Get GPIO to connect to PWM.
    uint32_t gpio = mp_hal_get_pin_obj(all_args[0]);

    // Get static peripheral object.
    uint slice = pwm_gpio_to_slice_num(gpio);
    uint8_t channel = pwm_gpio_to_channel(gpio);
    const machine_pwm_obj_t *self = &machine_pwm_obj[slice * 2 + channel];

    // Select PWM function for given GPIO.
    gpio_set_function(gpio, GPIO_FUNC_PWM);

    return MP_OBJ_FROM_PTR(self);
}

STATIC mp_obj_t machine_pwm_deinit(mp_obj_t self_in) {
    machine_pwm_obj_t *self = MP_OBJ_TO_PTR(self_in);
    pwm_set_enabled(self->slice, false);
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_pwm_deinit_obj, machine_pwm_deinit);

// PWM.freq([value])
STATIC mp_obj_t machine_pwm_freq(size_t n_args, const mp_obj_t *args) {
    machine_pwm_obj_t *self = MP_OBJ_TO_PTR(args[0]);
    uint32_t source_hz = clock_get_hz(clk_sys);
    if (n_args == 1) {
        // Get frequency.
        uint32_t div16 = pwm_hw->slice[self->slice].div;
        uint32_t top = pwm_hw->slice[self->slice].top;
        uint32_t pwm_freq = 16 * source_hz / div16 / top;
        return MP_OBJ_NEW_SMALL_INT(pwm_freq);
    } else {
        // Set the frequency, making "top" as large as possible for maximum resolution.
        // Maximum "top" is set at 65534 to be able to achieve 100% duty with 65535.
        #define TOP_MAX 65534
        mp_int_t freq = mp_obj_get_int(args[1]);
        uint32_t div16_top = 16 * source_hz / freq;
        uint32_t top = 1;
        for (;;) {
            // Try a few small prime factors to get close to the desired frequency.
            if (div16_top >= 16 * 5 && div16_top % 5 == 0 && top * 5 <= TOP_MAX) {
                div16_top /= 5;
                top *= 5;
            } else if (div16_top >= 16 * 3 && div16_top % 3 == 0 && top * 3 <= TOP_MAX) {
                div16_top /= 3;
                top *= 3;
            } else if (div16_top >= 16 * 2 && top * 2 <= TOP_MAX) {
                div16_top /= 2;
                top *= 2;
            } else {
                break;
            }
        }
        if (div16_top < 16) {
            mp_raise_ValueError(MP_ERROR_TEXT("freq too large"));
        } else if (div16_top >= 256 * 16) {
            mp_raise_ValueError(MP_ERROR_TEXT("freq too small"));
        }
        pwm_hw->slice[self->slice].div = div16_top;
        pwm_hw->slice[self->slice].top = top;
        return mp_const_none;
    }
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_pwm_freq_obj, 1, 2, machine_pwm_freq);

// PWM.duty_u16([value])
STATIC mp_obj_t machine_pwm_duty_u16(size_t n_args, const mp_obj_t *args) {
    machine_pwm_obj_t *self = MP_OBJ_TO_PTR(args[0]);
    uint32_t top = pwm_hw->slice[self->slice].top;
    if (n_args == 1) {
        // Get duty cycle.
        uint32_t cc = pwm_hw->slice[self->slice].cc;
        cc = (cc >> (self->channel ? PWM_CH0_CC_B_LSB : PWM_CH0_CC_A_LSB)) & 0xffff;
        return MP_OBJ_NEW_SMALL_INT(cc * 65535 / (top + 1));
    } else {
        // Set duty cycle.
        mp_int_t duty_u16 = mp_obj_get_int(args[1]);
        uint32_t cc = duty_u16 * (top + 1) / 65535;
        pwm_set_chan_level(self->slice, self->channel, cc);
        pwm_set_enabled(self->slice, true);
        return mp_const_none;
    }
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_pwm_duty_u16_obj, 1, 2, machine_pwm_duty_u16);

// PWM.duty_ns([value])
STATIC mp_obj_t machine_pwm_duty_ns(size_t n_args, const mp_obj_t *args) {
    machine_pwm_obj_t *self = MP_OBJ_TO_PTR(args[0]);
    uint32_t source_hz = clock_get_hz(clk_sys);
    uint32_t slice_hz = 16 * source_hz / pwm_hw->slice[self->slice].div;
    if (n_args == 1) {
        // Get duty cycle.
        uint32_t cc = pwm_hw->slice[self->slice].cc;
        cc = (cc >> (self->channel ? PWM_CH0_CC_B_LSB : PWM_CH0_CC_A_LSB)) & 0xffff;
        return MP_OBJ_NEW_SMALL_INT((uint64_t)cc * 1000000000ULL / slice_hz);
    } else {
        // Set duty cycle.
        mp_int_t duty_ns = mp_obj_get_int(args[1]);
        uint32_t cc = (uint64_t)duty_ns * slice_hz / 1000000000ULL;
        if (cc > 65535) {
            mp_raise_ValueError(MP_ERROR_TEXT("duty larger than period"));
        }
        pwm_set_chan_level(self->slice, self->channel, cc);
        pwm_set_enabled(self->slice, true);
        return mp_const_none;
    }
}
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(machine_pwm_duty_ns_obj, 1, 2, machine_pwm_duty_ns);

STATIC const mp_rom_map_elem_t machine_pwm_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&machine_pwm_deinit_obj) },
    { MP_ROM_QSTR(MP_QSTR_freq), MP_ROM_PTR(&machine_pwm_freq_obj) },
    { MP_ROM_QSTR(MP_QSTR_duty_u16), MP_ROM_PTR(&machine_pwm_duty_u16_obj) },
    { MP_ROM_QSTR(MP_QSTR_duty_ns), MP_ROM_PTR(&machine_pwm_duty_ns_obj) },
};
STATIC MP_DEFINE_CONST_DICT(machine_pwm_locals_dict, machine_pwm_locals_dict_table);

const mp_obj_type_t machine_pwm_type = {
    { &mp_type_type },
    .name = MP_QSTR_PWM,
    .print = machine_pwm_print,
    .make_new = machine_pwm_make_new,
    .locals_dict = (mp_obj_dict_t *)&machine_pwm_locals_dict,
};