blinky-esp/main/rmt_leds.cpp

static const char *TAG = "rmt_leds";
#include <esp_log.h>

#include <freertos/FreeRTOS.h>
#include <freertos/task.h>

#include "rmt_leds.hpp"


RMT_LEDs::RMT_LEDs(int _gpio, int length) :
            LEDStrip(length), gpio(_gpio), channel(NULL), rmt_block(NULL) {
    rmt_tx_channel_config_t config = {
        .gpio_num = gpio,
        .clk_src = RMT_CLK_SRC_DEFAULT,
        .resolution_hz = 3200000,   // (1.25 us / 4) => 3.2 MHz
        .mem_block_symbols = 64,    // memory block size, 64 * 4 = 256Bytes
        .trans_queue_depth = 1,     // We don't really need background transfers
        .flags = {
            .invert_out = false,
            .with_dma = false,       // TODO: Why no DMA??
            .io_loop_back = false,
        },
    };
    ESP_ERROR_CHECK(rmt_new_tx_channel(&config, &channel));
    ESP_ERROR_CHECK(rmt_enable(channel));
    configure(length);
}

void RMT_LEDs::configure(int n_leds) {
    if (rmt_block) {
        delete[] rmt_block;
        rmt_block = NULL;
    }
    if (n_leds <= 0) return;
    rmt_block = new rmt_symbol_word_t[n_leds * 24 + 1];
}

/*
static rmt_encoder_handle_t byte_enc;
static const rmt_bytes_encoder_config_t byte_enc_config = {
    .bit0 = {
        .duration0 = 1,
        .level0    = 1,
        .duration1 = 3,
        .level1    = 0,
    },
    .bit1 = {
        .duration0 = 2,
        .level0    = 1,
        .duration1 = 2,
        .level1    = 0,
    },
    .flags = {
        .msb_first = 1,
    },
};
static esp_err_t bytes_enc_ok = rmt_new_bytes_encoder(&byte_enc_config, &byte_enc);

static rmt_encoder_handle_t rst_enc;
static const rmt_copy_encoder_config_t rst_enc_config = {};
static esp_err_t rst_enc_ok = rmt_new_copy_encoder(&rst_enc_config, &rst_enc);
static const rmt_symbol_word_t rst_symbol = {
    .duration0 = 80,
    .level0    = 0,
    .duration1 = 80,
    .level1    = 0,
};

struct strip_encoder {
    rmt_encoder_t base;
    int state;
};

static size_t encode_strip(
            rmt_encoder_t *_encoder, rmt_channel_handle_t channel,
            const void *data, size_t n_bytes, rmt_encode_state_t *ret_state
        ) {
    strip_encoder *encoder = __containerof(_encoder, strip_encoder, base);
    size_t n_encoded = 0;
    rmt_encode_state_t substate = 0;
    rmt_encode_state_t state = 0;

    switch(encoder->state) {
    case 0:
        n_encoded += byte_enc.encode(&byte_enc, channel, data, n_bytes, &substate);
        if (substate & RMT_ENCODING_COMPLETE) {
            encoder->state = 1;
            break;
        }

    case 1:
        n_encoded += rst_enc.encode(
                &rst_enc, channel, &rst_symbol, sizeof(rst_symbol), &substate);
        if (substate & RMT_ENCODING_COMPLETE) {
            encoder->state = 0;
            state |= RMT_ENCODING_COMPLETE;
        }
        if (substate & RMT_ENCODING_MEM_FULL) {
            state |= RMT_ENCODING_MEM_FULL;
        }
    }

    *ret_state = state;
    return n_encoded;
}

static esp_err_t reset_strip_encoder(rmt_encoder_t *encoder) {
    strip_encoder *encoder = __containerof(encoder, strip_encoder, base);
    rmt_encoder_reset(byte_enc);
    rmt_encoder_reset(rst_enc);
    encoder->state = 0;
    return ESP_OK;
}

static esp_err_t rmt_del_led_strip_encoder(rmt_encoder_t *encoder) {
    strip_encoder *encoder = __containerof(encoder, strip_encoder, base);
    delete encoder;
    return ESP_OK;
}

static rmt_encoder_t* make_strip_encoder() {
    enc = new strip_encoder {
        .base = {
            .encode = encode_strip,
            .reset = reset_strip_encoder,
            .del = del_strip_encoder,
        },
        .state = 0
    }
}
*/


static rmt_encoder_handle_t encoder;
static const rmt_copy_encoder_config_t copy_encoder_config = {};
static esp_err_t copy_encoder_ok = rmt_new_copy_encoder(
        &copy_encoder_config, &encoder
    );

constexpr rmt_symbol_word_t sym_0 = {
        .duration0 = 1,
        .level0    = 1,
        .duration1 = 3,
        .level1    = 0,
    };

constexpr rmt_symbol_word_t sym_1 = {
        .duration0 = 2,
        .level0    = 1,
        .duration1 = 2,
        .level1    = 0,
    };

constexpr rmt_symbol_word_t sym_reset = {
    .duration0 = 80,
    .level0    = 0,
    .duration1 = 80,
    .level1    = 0,
};

static inline rmt_symbol_word_t* encode_byte(rmt_symbol_word_t *sym, uint8_t x) {
    for (int i = 8; i > 0; --i) {
        *sym = (x & 0x80) ? sym_1 : sym_0;
        x <<= 1;
        ++sym;
    }
    return sym;
}


/*** *** ***
static std::string termcolor(Color c) {
    return "\x1b[48;2;" +
            std::to_string((int)c.r) + ";" +
            std::to_string((int)c.g) + ";" +
            std::to_string((int)c.b) + "m";
}

static void show_terminal_LEDs(const Color *pixels, int length) {
    std::string line;
    for (int i = 0; i < length; i++) {
        line += termcolor(pixels[i]) + " ";
    }
    line += "\x1b[0m";
    ESP_LOGI(TAG, "%s", line.c_str());
}
*** *** ***/

void RMT_LEDs::show() {
    static const rmt_transmit_config_t config = {
        .loop_count = 0,
        .flags = {
            .eot_level = 0,
        },
    };

    rmt_symbol_word_t *sym = rmt_block;
    Color *pixel = pixels;
    for (int i = length; i > 0; --i) {
        sym = encode_byte(sym, pixel->r);
        sym = encode_byte(sym, pixel->g);
        sym = encode_byte(sym, pixel->b);
        ++pixel;
    }
    *sym++ = sym_reset;

    //show_terminal_LEDs(pixels, length);

    esp_err_t err = rmt_tx_wait_all_done(channel, -1);
    if (err) ESP_LOGE(TAG, "Failed to wait for TX complete: %d", err);

    ESP_ERROR_CHECK(rmt_transmit(
            channel, encoder,
            //pixels, length * sizeof(*pixels),
            rmt_block, (length * 24 + 1) * sizeof(*rmt_block),
            &config
        ));
}