ports/esp32/esp32_rmt.c - lite/micropython - Linaro Git Browser

 /*
  * 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/mphal.h"
 #include "py/runtime.h"
 #include "modmachine.h"
 #include "modesp32.h"

 #include "esp_task.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.

 // Last available RMT channel that can transmit.
 #define RMT_LAST_TX_CHANNEL (SOC_RMT_TX_CANDIDATES_PER_GROUP - 1)

 // 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;
     mp_uint_t num_items;
     rmt_item32_t *items;
     bool loop_en;
 } esp32_rmt_obj_t;

 // Current channel used for machine.bitstream, in the machine_bitstream_high_low_rmt
 // implementation.  A value of -1 means do not use RMT.
 int8_t esp32_rmt_bitstream_channel_id = RMT_LAST_TX_CHANNEL;

 #if MP_TASK_COREID == 0

 typedef struct _rmt_install_state_t {
     SemaphoreHandle_t handle;
     uint8_t channel_id;
     esp_err_t ret;
 } rmt_install_state_t;

 static void rmt_install_task(void *pvParameter) {
     rmt_install_state_t *state = pvParameter;
     state->ret = rmt_driver_install(state->channel_id, 0, 0);
     xSemaphoreGive(state->handle);
     vTaskDelete(NULL);
     for (;;) {
     }
 }

 // Call rmt_driver_install on core 1.  This ensures that the RMT interrupt handler is
 // serviced on core 1, so that WiFi (if active) does not interrupt it and cause glitches.
 esp_err_t rmt_driver_install_core1(uint8_t channel_id) {
     TaskHandle_t th;
     rmt_install_state_t state;
     state.handle = xSemaphoreCreateBinary();
     state.channel_id = channel_id;
     xTaskCreatePinnedToCore(rmt_install_task, "rmt_install_task", 2048 / sizeof(StackType_t), &state, ESP_TASK_PRIO_MIN + 1, &th, 1);
     xSemaphoreTake(state.handle, portMAX_DELAY);
     vSemaphoreDelete(state.handle);
     return state.ret;
 }

 #else

 // MicroPython runs on core 1, so we can call the RMT installer directly and its
 // interrupt handler will also run on core 1.
 esp_err_t rmt_driver_install_core1(uint8_t channel_id) {
     return rmt_driver_install(channel_id, 0, 0);
 }

 #endif

 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_idle_level,                  MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} }, // low voltage
         { MP_QSTR_tx_carrier,                  MP_ARG_KW_ONLY | MP_ARG_OBJ, {.u_obj = mp_const_none} }, // no carrier
     };
     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;
     mp_uint_t idle_level = args[3].u_bool;
     mp_obj_t tx_carrier_obj = args[4].u_obj;

     if (esp32_rmt_bitstream_channel_id >= 0 && channel_id == esp32_rmt_bitstream_channel_id) {
         mp_raise_ValueError(MP_ERROR_TEXT("channel used by bitstream"));
     }

     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 = mp_obj_malloc_with_finaliser(esp32_rmt_obj_t, &esp32_rmt_type);
     self->channel_id = channel_id;
     self->pin = pin_id;
     self->clock_div = clock_div;
     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;

     if (tx_carrier_obj != mp_const_none) {
         mp_obj_t *tx_carrier_details = NULL;
         mp_obj_get_array_fixed_n(tx_carrier_obj, 3, &tx_carrier_details);
         mp_uint_t frequency = mp_obj_get_int(tx_carrier_details[0]);
         mp_uint_t duty = mp_obj_get_int(tx_carrier_details[1]);
         mp_uint_t level = mp_obj_is_true(tx_carrier_details[2]);

         if (frequency == 0) {
             mp_raise_ValueError(MP_ERROR_TEXT("tx_carrier frequency must be >0"));
         }
         if (duty > 100) {
             mp_raise_ValueError(MP_ERROR_TEXT("tx_carrier duty must be 0..100"));
         }

         config.tx_config.carrier_en = 1;
         config.tx_config.carrier_freq_hz = frequency;
         config.tx_config.carrier_duty_percent = duty;
         config.tx_config.carrier_level = level;
     } else {
         config.tx_config.carrier_en = 0;
     }

     config.tx_config.idle_output_en = 1;
     config.tx_config.idle_level = idle_level;

     config.clk_div = self->clock_div;

     check_esp_err(rmt_config(&config));
     check_esp_err(rmt_driver_install_core1(config.channel));

     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) {
         bool idle_output_en;
         rmt_idle_level_t idle_level;
         check_esp_err(rmt_get_idle_level(self->channel_id, &idle_output_en, &idle_level));
         mp_printf(print, "RMT(channel=%u, pin=%u, source_freq=%u, clock_div=%u, idle_level=%u)",
             self->channel_id, self->pin, APB_CLK_FREQ, self->clock_div, idle_level);
     } 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() {
     return mp_obj_new_int(APB_CLK_FREQ);
 }
 static MP_DEFINE_CONST_FUN_OBJ_0(esp32_rmt_source_freq_obj, esp32_rmt_source_freq);
 static MP_DEFINE_CONST_STATICMETHOD_OBJ(esp32_rmt_source_obj, MP_ROM_PTR(&esp32_rmt_source_freq_obj));

 // 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 milliseconds), 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 / portTICK_PERIOD_MS);
     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 *args) {
     esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(args[0]);
     mp_obj_t duration_obj = args[1];
     mp_obj_t data_obj = n_args > 2 ? args[2] : mp_const_true;

     mp_uint_t duration = 0;
     size_t duration_length = 0;
     mp_obj_t *duration_ptr = NULL;
     mp_uint_t data = 0;
     size_t data_length = 0;
     mp_obj_t *data_ptr = NULL;
     mp_uint_t num_pulses = 0;

     if (!(mp_obj_is_type(data_obj, &mp_type_tuple) || mp_obj_is_type(data_obj, &mp_type_list))) {
         // Mode 1: array of durations, toggle initial data value
         mp_obj_get_array(duration_obj, &duration_length, &duration_ptr);
         data = mp_obj_is_true(data_obj);
         num_pulses = duration_length;
     } else if (mp_obj_is_int(duration_obj)) {
         // Mode 2: constant duration, array of data values
         duration = mp_obj_get_int(duration_obj);
         mp_obj_get_array(data_obj, &data_length, &data_ptr);
         num_pulses = data_length;
     } else {
         // Mode 3: arrays of durations and data values
         mp_obj_get_array(duration_obj, &duration_length, &duration_ptr);
         mp_obj_get_array(data_obj, &data_length, &data_ptr);
         if (duration_length != data_length) {
             mp_raise_ValueError(MP_ERROR_TEXT("duration and data must have same length"));
         }
         num_pulses = duration_length;
     }

     if (num_pulses == 0) {
         mp_raise_ValueError(MP_ERROR_TEXT("No pulses"));
     }
     if (self->loop_en && num_pulses > 126) {
         mp_raise_ValueError(MP_ERROR_TEXT("Too many pulses for loop"));
     }

     mp_uint_t num_items = (num_pulses / 2) + (num_pulses % 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, pulse_index = 0; item_index < num_items; item_index++) {
         self->items[item_index].duration0 = duration_length ? mp_obj_get_int(duration_ptr[pulse_index]) : duration;
         self->items[item_index].level0 = data_length ? mp_obj_is_true(data_ptr[pulse_index]) : data++;
         pulse_index++;
         if (pulse_index < num_pulses) {
             self->items[item_index].duration1 = duration_length ? mp_obj_get_int(duration_ptr[pulse_index]) : duration;
             self->items[item_index].level1 = data_length ? mp_obj_is_true(data_ptr[pulse_index]) : data++;
             pulse_index++;
         } else {
             self->items[item_index].duration1 = 0;
             self->items[item_index].level1 = 0;
         }
     }

     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));
     }

     #if !CONFIG_IDF_TARGET_ESP32S3
     check_esp_err(rmt_write_items(self->channel_id, self->items, num_items, false));
     #endif

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

     #if CONFIG_IDF_TARGET_ESP32S3
     check_esp_err(rmt_write_items(self->channel_id, self->items, num_items, false));
     #endif

     return mp_const_none;
 }
 static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp32_rmt_write_pulses_obj, 2, 3, esp32_rmt_write_pulses);

 static mp_obj_t esp32_rmt_bitstream_channel(size_t n_args, const mp_obj_t *args) {
     if (n_args > 0) {
         if (args[0] == mp_const_none) {
             esp32_rmt_bitstream_channel_id = -1;
         } else {
             mp_int_t channel_id = mp_obj_get_int(args[0]);
             if (channel_id < 0 || channel_id > RMT_LAST_TX_CHANNEL) {
                 mp_raise_ValueError(MP_ERROR_TEXT("invalid channel"));
             }
             esp32_rmt_bitstream_channel_id = channel_id;
         }
     }
     if (esp32_rmt_bitstream_channel_id < 0) {
         return mp_const_none;
     } else {
         return MP_OBJ_NEW_SMALL_INT(esp32_rmt_bitstream_channel_id);
     }
 }
 static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp32_rmt_bitstream_channel_fun_obj, 0, 1, esp32_rmt_bitstream_channel);
 static MP_DEFINE_CONST_STATICMETHOD_OBJ(esp32_rmt_bitstream_channel_obj, MP_ROM_PTR(&esp32_rmt_bitstream_channel_fun_obj));

 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_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 methods
     { MP_ROM_QSTR(MP_QSTR_bitstream_channel), MP_ROM_PTR(&esp32_rmt_bitstream_channel_obj) },

     // Class methods
     { MP_ROM_QSTR(MP_QSTR_source_freq), MP_ROM_PTR(&esp32_rmt_source_obj) },

     // Constants
     { MP_ROM_QSTR(MP_QSTR_PULSE_MAX), MP_ROM_INT(32767) },
 };
 static MP_DEFINE_CONST_DICT(esp32_rmt_locals_dict, esp32_rmt_locals_dict_table);

 MP_DEFINE_CONST_OBJ_TYPE(
     esp32_rmt_type,
     MP_QSTR_RMT,
     MP_TYPE_FLAG_NONE,
     make_new, esp32_rmt_make_new,
     print, esp32_rmt_print,
     locals_dict, &esp32_rmt_locals_dict
     );
	/*
	* 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/mphal.h"
	#include "py/runtime.h"
	#include "modmachine.h"
	#include "modesp32.h"

	#include "esp_task.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.

	// Last available RMT channel that can transmit.
	#define RMT_LAST_TX_CHANNEL (SOC_RMT_TX_CANDIDATES_PER_GROUP - 1)

	// 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;
	mp_uint_t num_items;
	rmt_item32_t *items;
	bool loop_en;
	} esp32_rmt_obj_t;

	// Current channel used for machine.bitstream, in the machine_bitstream_high_low_rmt
	// implementation. A value of -1 means do not use RMT.
	int8_t esp32_rmt_bitstream_channel_id = RMT_LAST_TX_CHANNEL;

	#if MP_TASK_COREID == 0

	typedef struct _rmt_install_state_t {
	SemaphoreHandle_t handle;
	uint8_t channel_id;
	esp_err_t ret;
	} rmt_install_state_t;

	static void rmt_install_task(void *pvParameter) {
	rmt_install_state_t *state = pvParameter;
	state->ret = rmt_driver_install(state->channel_id, 0, 0);
	xSemaphoreGive(state->handle);
	vTaskDelete(NULL);
	for (;;) {
	}
	}

	// Call rmt_driver_install on core 1. This ensures that the RMT interrupt handler is
	// serviced on core 1, so that WiFi (if active) does not interrupt it and cause glitches.
	esp_err_t rmt_driver_install_core1(uint8_t channel_id) {
	TaskHandle_t th;
	rmt_install_state_t state;
	state.handle = xSemaphoreCreateBinary();
	state.channel_id = channel_id;
	xTaskCreatePinnedToCore(rmt_install_task, "rmt_install_task", 2048 / sizeof(StackType_t), &state, ESP_TASK_PRIO_MIN + 1, &th, 1);
	xSemaphoreTake(state.handle, portMAX_DELAY);
	vSemaphoreDelete(state.handle);
	return state.ret;
	}

	#else

	// MicroPython runs on core 1, so we can call the RMT installer directly and its
	// interrupt handler will also run on core 1.
	esp_err_t rmt_driver_install_core1(uint8_t channel_id) {
	return rmt_driver_install(channel_id, 0, 0);
	}

	#endif

	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_idle_level, MP_ARG_KW_ONLY \| MP_ARG_BOOL, {.u_bool = false} }, // low voltage
	{ MP_QSTR_tx_carrier, MP_ARG_KW_ONLY \| MP_ARG_OBJ, {.u_obj = mp_const_none} }, // no carrier
	};
	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;
	mp_uint_t idle_level = args[3].u_bool;
	mp_obj_t tx_carrier_obj = args[4].u_obj;

	if (esp32_rmt_bitstream_channel_id >= 0 && channel_id == esp32_rmt_bitstream_channel_id) {
	mp_raise_ValueError(MP_ERROR_TEXT("channel used by bitstream"));
	}

	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 = mp_obj_malloc_with_finaliser(esp32_rmt_obj_t, &esp32_rmt_type);
	self->channel_id = channel_id;
	self->pin = pin_id;
	self->clock_div = clock_div;
	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;

	if (tx_carrier_obj != mp_const_none) {
	mp_obj_t *tx_carrier_details = NULL;
	mp_obj_get_array_fixed_n(tx_carrier_obj, 3, &tx_carrier_details);
	mp_uint_t frequency = mp_obj_get_int(tx_carrier_details[0]);
	mp_uint_t duty = mp_obj_get_int(tx_carrier_details[1]);
	mp_uint_t level = mp_obj_is_true(tx_carrier_details[2]);

	if (frequency == 0) {
	mp_raise_ValueError(MP_ERROR_TEXT("tx_carrier frequency must be >0"));
	}
	if (duty > 100) {
	mp_raise_ValueError(MP_ERROR_TEXT("tx_carrier duty must be 0..100"));
	}

	config.tx_config.carrier_en = 1;
	config.tx_config.carrier_freq_hz = frequency;
	config.tx_config.carrier_duty_percent = duty;
	config.tx_config.carrier_level = level;
	} else {
	config.tx_config.carrier_en = 0;
	}

	config.tx_config.idle_output_en = 1;
	config.tx_config.idle_level = idle_level;

	config.clk_div = self->clock_div;

	check_esp_err(rmt_config(&config));
	check_esp_err(rmt_driver_install_core1(config.channel));

	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) {
	bool idle_output_en;
	rmt_idle_level_t idle_level;
	check_esp_err(rmt_get_idle_level(self->channel_id, &idle_output_en, &idle_level));
	mp_printf(print, "RMT(channel=%u, pin=%u, source_freq=%u, clock_div=%u, idle_level=%u)",
	self->channel_id, self->pin, APB_CLK_FREQ, self->clock_div, idle_level);
	} 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() {
	return mp_obj_new_int(APB_CLK_FREQ);
	}
	static MP_DEFINE_CONST_FUN_OBJ_0(esp32_rmt_source_freq_obj, esp32_rmt_source_freq);
	static MP_DEFINE_CONST_STATICMETHOD_OBJ(esp32_rmt_source_obj, MP_ROM_PTR(&esp32_rmt_source_freq_obj));

	// 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 milliseconds), 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 / portTICK_PERIOD_MS);
	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 *args) {
	esp32_rmt_obj_t *self = MP_OBJ_TO_PTR(args[0]);
	mp_obj_t duration_obj = args[1];
	mp_obj_t data_obj = n_args > 2 ? args[2] : mp_const_true;

	mp_uint_t duration = 0;
	size_t duration_length = 0;
	mp_obj_t *duration_ptr = NULL;
	mp_uint_t data = 0;
	size_t data_length = 0;
	mp_obj_t *data_ptr = NULL;
	mp_uint_t num_pulses = 0;

	if (!(mp_obj_is_type(data_obj, &mp_type_tuple) \|\| mp_obj_is_type(data_obj, &mp_type_list))) {
	// Mode 1: array of durations, toggle initial data value
	mp_obj_get_array(duration_obj, &duration_length, &duration_ptr);
	data = mp_obj_is_true(data_obj);
	num_pulses = duration_length;
	} else if (mp_obj_is_int(duration_obj)) {
	// Mode 2: constant duration, array of data values
	duration = mp_obj_get_int(duration_obj);
	mp_obj_get_array(data_obj, &data_length, &data_ptr);
	num_pulses = data_length;
	} else {
	// Mode 3: arrays of durations and data values
	mp_obj_get_array(duration_obj, &duration_length, &duration_ptr);
	mp_obj_get_array(data_obj, &data_length, &data_ptr);
	if (duration_length != data_length) {
	mp_raise_ValueError(MP_ERROR_TEXT("duration and data must have same length"));
	}
	num_pulses = duration_length;
	}

	if (num_pulses == 0) {
	mp_raise_ValueError(MP_ERROR_TEXT("No pulses"));
	}
	if (self->loop_en && num_pulses > 126) {
	mp_raise_ValueError(MP_ERROR_TEXT("Too many pulses for loop"));
	}

	mp_uint_t num_items = (num_pulses / 2) + (num_pulses % 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, pulse_index = 0; item_index < num_items; item_index++) {
	self->items[item_index].duration0 = duration_length ? mp_obj_get_int(duration_ptr[pulse_index]) : duration;
	self->items[item_index].level0 = data_length ? mp_obj_is_true(data_ptr[pulse_index]) : data++;
	pulse_index++;
	if (pulse_index < num_pulses) {
	self->items[item_index].duration1 = duration_length ? mp_obj_get_int(duration_ptr[pulse_index]) : duration;
	self->items[item_index].level1 = data_length ? mp_obj_is_true(data_ptr[pulse_index]) : data++;
	pulse_index++;
	} else {
	self->items[item_index].duration1 = 0;
	self->items[item_index].level1 = 0;
	}
	}

	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));
	}

	#if !CONFIG_IDF_TARGET_ESP32S3
	check_esp_err(rmt_write_items(self->channel_id, self->items, num_items, false));
	#endif

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

	#if CONFIG_IDF_TARGET_ESP32S3
	check_esp_err(rmt_write_items(self->channel_id, self->items, num_items, false));
	#endif

	return mp_const_none;
	}
	static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp32_rmt_write_pulses_obj, 2, 3, esp32_rmt_write_pulses);

	static mp_obj_t esp32_rmt_bitstream_channel(size_t n_args, const mp_obj_t *args) {
	if (n_args > 0) {
	if (args[0] == mp_const_none) {
	esp32_rmt_bitstream_channel_id = -1;
	} else {
	mp_int_t channel_id = mp_obj_get_int(args[0]);
	if (channel_id < 0 \|\| channel_id > RMT_LAST_TX_CHANNEL) {
	mp_raise_ValueError(MP_ERROR_TEXT("invalid channel"));
	}
	esp32_rmt_bitstream_channel_id = channel_id;
	}
	}
	if (esp32_rmt_bitstream_channel_id < 0) {
	return mp_const_none;
	} else {
	return MP_OBJ_NEW_SMALL_INT(esp32_rmt_bitstream_channel_id);
	}
	}
	static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(esp32_rmt_bitstream_channel_fun_obj, 0, 1, esp32_rmt_bitstream_channel);
	static MP_DEFINE_CONST_STATICMETHOD_OBJ(esp32_rmt_bitstream_channel_obj, MP_ROM_PTR(&esp32_rmt_bitstream_channel_fun_obj));

	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_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 methods
	{ MP_ROM_QSTR(MP_QSTR_bitstream_channel), MP_ROM_PTR(&esp32_rmt_bitstream_channel_obj) },

	// Class methods
	{ MP_ROM_QSTR(MP_QSTR_source_freq), MP_ROM_PTR(&esp32_rmt_source_obj) },

	// Constants
	{ MP_ROM_QSTR(MP_QSTR_PULSE_MAX), MP_ROM_INT(32767) },
	};
	static MP_DEFINE_CONST_DICT(esp32_rmt_locals_dict, esp32_rmt_locals_dict_table);

	MP_DEFINE_CONST_OBJ_TYPE(
	esp32_rmt_type,
	MP_QSTR_RMT,
	MP_TYPE_FLAG_NONE,
	make_new, esp32_rmt_make_new,
	print, esp32_rmt_print,
	locals_dict, &esp32_rmt_locals_dict
	);