esp32_rmt.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2019 "Matt Trentini" <matt.trentini@gmail.com>
 *
 * 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 "modmachine.h"
#include "mphalport.h"
#include "driver/rmt.h"

// This exposes the ESP32's RMT module to MicroPython. RMT is provided by the Espressif ESP-IDF:
//
//    https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/rmt.html
//
// With some examples provided:
//
//    https://github.com/espressif/arduino-esp32/tree/master/libraries/ESP32/examples/RMT
//
// RMT allows accurate (down to 12.5ns resolution) transmit - and receive - of pulse signals.
// Originally designed to generate infrared remote control signals, the module is very
// flexible and quite easy-to-use.
//
// This current MicroPython implementation lacks some major features, notably receive pulses
// and carrier output.

// Forward declaration
extern const mp_obj_type_t esp32_rmt_type;

typedef struct _esp32_rmt_obj_t {
    mp_obj_base_t base;
    uint8_t channel_id;
    gpio_num_t pin;
    uint8_t clock_div;
    uint16_t carrier_duty_percent;
    uint32_t carrier_freq;
    mp_uint_t num_items;
    rmt_item32_t *items;
    bool loop_en;
} esp32_rmt_obj_t;

STATIC mp_obj_t esp32_rmt_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *all_args) {
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_id,        MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = -1} },
        { MP_QSTR_pin,       MP_ARG_REQUIRED | MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} },
        { MP_QSTR_clock_div,                   MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 8} }, // 100ns resolution
        { MP_QSTR_carrier_duty_percent,        MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 50} },
        { MP_QSTR_carrier_freq,                MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
    };
    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all_kw_array(n_args, n_kw, all_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
    mp_uint_t channel_id = args[0].u_int;
    gpio_num_t pin_id = machine_pin_get_id(args[1].u_obj);
    mp_uint_t clock_div = args[2].u_int;

    bool carrier_en = false;
    mp_uint_t carrier_duty_percent = 0;
    mp_uint_t carrier_freq = 0;

    if (args[4].u_int > 0) {
        carrier_en = true;
        carrier_duty_percent = args[3].u_int;
        carrier_freq = args[4].u_int;
    }

    if (clock_div < 1 || clock_div > 255) {
        mp_raise_ValueError(MP_ERROR_TEXT("clock_div must be between 1 and 255"));
    }

    esp32_rmt_obj_t *self = m_new_obj_with_finaliser(esp32_rmt_obj_t);
    self->base.type = &esp32_rmt_type;
    self->channel_id = channel_id;
    self->pin = pin_id;
    self->clock_div = clock_div;
    self->carrier_duty_percent = carrier_duty_percent;
    self->carrier_freq = carrier_freq;
    self->loop_en = false;

    rmt_config_t config = {0};
    config.rmt_mode = RMT_MODE_TX;
    config.channel = (rmt_channel_t)self->channel_id;
    config.gpio_num = self->pin;
    config.mem_block_num = 1;
    config.tx_config.loop_en = 0;

    config.tx_config.carrier_en = carrier_en;
    config.tx_config.idle_output_en = 1;
    config.tx_config.idle_level = 0;
    config.tx_config.carrier_duty_percent = self->carrier_duty_percent;
    config.tx_config.carrier_freq_hz = self->carrier_freq;
    config.tx_config.carrier_level = 1;

    config.clk_div = self->clock_div;

    check_esp_err(rmt_config(&config));
    check_esp_err(rmt_driver_install(config.channel, 0, 0));

    return MP_OBJ_FROM_PTR(self);
}

STATIC void esp32_rmt_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(self_in);
    if (self->pin != -1) {
        mp_printf(print, "RMT(channel=%u, pin=%u, source_freq=%u, clock_div=%u",
            self->channel_id, self->pin, APB_CLK_FREQ, self->clock_div);
        if (self->carrier_freq > 0) {
            mp_printf(print, ", carrier_freq=%u, carrier_duty_percent=%u)",
                self->carrier_freq, self->carrier_duty_percent);
        } else {
            mp_printf(print, ")");
        }
    } else {
        mp_printf(print, "RMT()");
    }
}

STATIC mp_obj_t esp32_rmt_deinit(mp_obj_t self_in) {
    // fixme: check for valid channel. Return exception if error occurs.
    esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(self_in);
    if (self->pin != -1) { // Check if channel has already been deinitialised.
        rmt_driver_uninstall(self->channel_id);
        self->pin = -1; // -1 to indicate RMT is unused
        m_free(self->items);
    }
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(esp32_rmt_deinit_obj, esp32_rmt_deinit);

// Return the source frequency.
// Currently only the APB clock (80MHz) can be used but it is possible other
// clock sources will added in the future.
STATIC mp_obj_t esp32_rmt_source_freq(mp_obj_t self_in) {
    return mp_obj_new_int(APB_CLK_FREQ);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(esp32_rmt_source_freq_obj, esp32_rmt_source_freq);

// Return the clock divider.
STATIC mp_obj_t esp32_rmt_clock_div(mp_obj_t self_in) {
    esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(self_in);
    return mp_obj_new_int(self->clock_div);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(esp32_rmt_clock_div_obj, esp32_rmt_clock_div);

// Query whether the channel has finished sending pulses. Takes an optional
// timeout (in ticks of the 80MHz clock), returning true if the pulse stream has
// completed or false if they are still transmitting (or timeout is reached).
STATIC mp_obj_t esp32_rmt_wait_done(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_self,    MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = mp_const_none} },
        { MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
    };

    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(args[0].u_obj);

    esp_err_t err = rmt_wait_tx_done(self->channel_id, args[1].u_int);
    return err == ESP_OK ? mp_const_true : mp_const_false;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(esp32_rmt_wait_done_obj, 1, esp32_rmt_wait_done);

STATIC mp_obj_t esp32_rmt_loop(mp_obj_t self_in, mp_obj_t loop) {
    esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(self_in);
    self->loop_en = mp_obj_get_int(loop);
    if (!self->loop_en) {
        bool loop_en;
        check_esp_err(rmt_get_tx_loop_mode(self->channel_id, &loop_en));
        if (loop_en) {
            check_esp_err(rmt_set_tx_loop_mode(self->channel_id, false));
            check_esp_err(rmt_set_tx_intr_en(self->channel_id, true));
        }
    }
    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_2(esp32_rmt_loop_obj, esp32_rmt_loop);

STATIC mp_obj_t esp32_rmt_write_pulses(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_self,   MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = mp_const_none} },
        { MP_QSTR_pulses, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = mp_const_none} },
        { MP_QSTR_start,  MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 1} },
    };

    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);

    esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(args[0].u_obj);
    mp_obj_t pulses = args[1].u_obj;
    mp_uint_t start = args[2].u_int;

    if (start > 1) {
        mp_raise_ValueError(MP_ERROR_TEXT("start must be 0 or 1"));
    }

    size_t pulses_length = 0;
    mp_obj_t *pulses_ptr = NULL;
    mp_obj_get_array(pulses, &pulses_length, &pulses_ptr);

    mp_uint_t num_items = (pulses_length / 2) + (pulses_length % 2);
    if (num_items > self->num_items) {
        self->items = (rmt_item32_t *)m_realloc(self->items, num_items * sizeof(rmt_item32_t *));
        self->num_items = num_items;
    }

    for (mp_uint_t item_index = 0; item_index < num_items; item_index++) {
        mp_uint_t pulse_index = item_index * 2;
        self->items[item_index].duration0 = mp_obj_get_int(pulses_ptr[pulse_index++]);
        self->items[item_index].level0 = start++; // Note that start _could_ wrap.
        if (pulse_index < pulses_length) {
            self->items[item_index].duration1 = mp_obj_get_int(pulses_ptr[pulse_index]);
            self->items[item_index].level1 = start++;
        }
    }

    if (self->loop_en) {
        bool loop_en;
        check_esp_err(rmt_get_tx_loop_mode(self->channel_id, &loop_en));
        if (loop_en) {
            check_esp_err(rmt_set_tx_intr_en(self->channel_id, true));
            check_esp_err(rmt_set_tx_loop_mode(self->channel_id, false));
        }
        check_esp_err(rmt_wait_tx_done(self->channel_id, portMAX_DELAY));
        check_esp_err(rmt_set_tx_intr_en(self->channel_id, false));
    }

    check_esp_err(rmt_write_items(self->channel_id, self->items, num_items, false /* non-blocking */));

    if (self->loop_en) {
        check_esp_err(rmt_set_tx_loop_mode(self->channel_id, true));
    }

    return mp_const_none;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(esp32_rmt_write_pulses_obj, 2, esp32_rmt_write_pulses);

STATIC const mp_rom_map_elem_t esp32_rmt_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR___del__), MP_ROM_PTR(&esp32_rmt_deinit_obj) },
    { MP_ROM_QSTR(MP_QSTR_deinit), MP_ROM_PTR(&esp32_rmt_deinit_obj) },
    { MP_ROM_QSTR(MP_QSTR_source_freq), MP_ROM_PTR(&esp32_rmt_source_freq_obj) },
    { MP_ROM_QSTR(MP_QSTR_clock_div), MP_ROM_PTR(&esp32_rmt_clock_div_obj) },
    { MP_ROM_QSTR(MP_QSTR_wait_done), MP_ROM_PTR(&esp32_rmt_wait_done_obj) },
    { MP_ROM_QSTR(MP_QSTR_loop), MP_ROM_PTR(&esp32_rmt_loop_obj) },
    { MP_ROM_QSTR(MP_QSTR_write_pulses), MP_ROM_PTR(&esp32_rmt_write_pulses_obj) },
};
STATIC MP_DEFINE_CONST_DICT(esp32_rmt_locals_dict, esp32_rmt_locals_dict_table);

const mp_obj_type_t esp32_rmt_type = {
    { &mp_type_type },
    .name = MP_QSTR_RMT,
    .print = esp32_rmt_print,
    .make_new = esp32_rmt_make_new,
    .locals_dict = (mp_obj_dict_t *)&esp32_rmt_locals_dict,
};