120 lines
3.1 KiB
C
120 lines
3.1 KiB
C
/* RMT transmit example
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_log.h"
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#include "driver/rmt.h"
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static const char *RMT_TX_TAG = "RMT Tx";
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#define RMT_TX_CHANNEL RMT_CHANNEL_0
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#define RMT_TX_GPIO 18
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#define RMT_MESSAGE_LENGTH 12
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rmt_item32_t items[RMT_MESSAGE_LENGTH];
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/*
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* Prepare a table with a message in the Morse code
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*
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* The message is "ESP" : . ... .--.
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*
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* The table structure:
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* {duration, level, duration, level}
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*
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*/
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uint32_t message[RMT_MESSAGE_LENGTH][4] = {
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// E : dot
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{32767, 1, 32767, 0}, // dot
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//
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{32767, 0, 32767, 0}, // SPACE
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// S : dot, dot, dot
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{32767, 1, 32767, 0}, // dot
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{32767, 1, 32767, 0}, // dot
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{32767, 1, 32767, 0}, // dot
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//
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{32767, 0, 32767, 0}, // SPACE
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// P : dot, dash, dash, dot
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{32767, 1, 32767, 0}, // dot
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{32767, 1, 32767, 1},
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{32767, 1, 32767, 0}, // dash
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{32767, 1, 32767, 1},
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{32767, 1, 32767, 0}, // dash
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{32767, 1, 32767, 0} // dot
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};
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/*
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* Populate the RMT items array
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* with a previously prepared message
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*/
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static void populate_rmt_items(void)
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{
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for (int i = 0; i < RMT_MESSAGE_LENGTH; i++) {
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items[i].duration0 = message[i][0];
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items[i].level0 = message[i][1];
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items[i].duration1 = message[i][2];
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items[i].level1 = message[i][3];
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}
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}
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/*
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* Initialize the RMT Tx channel
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*/
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static void rmt_tx_int()
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{
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rmt_config_t config;
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config.rmt_mode = RMT_MODE_TX;
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config.channel = RMT_TX_CHANNEL;
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config.gpio_num = RMT_TX_GPIO;
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config.mem_block_num = 1;
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config.tx_config.loop_en = 0;
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// enable the carrier to be able to hear the Morse sound
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// if the RMT_TX_GPIO is connected to a speaker
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config.tx_config.carrier_en = 1;
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config.tx_config.idle_output_en = 1;
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config.tx_config.idle_level = 0;
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config.tx_config.carrier_duty_percent = 50;
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// set audible career frequency of 611 Hz
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// actually 611 Hz is the minimum, that can be set
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// with current implementation of the RMT API
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config.tx_config.carrier_freq_hz = 611;
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config.tx_config.carrier_level = 1;
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// set the maximum clock divider to be able to output
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// RMT pulses in range of about one hundred milliseconds
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config.clk_div = 255;
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ESP_ERROR_CHECK(rmt_config(&config));
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ESP_ERROR_CHECK(rmt_driver_install(config.channel, 0, 0));
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}
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/*
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* Transmit all the items in a loop
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*/
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static void rmt_tx_task(void *ignore)
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{
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while (1) {
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ESP_ERROR_CHECK(rmt_write_items(RMT_TX_CHANNEL, items, RMT_MESSAGE_LENGTH, 1));
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ESP_LOGI(RMT_TX_TAG, "Transmission complete");
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vTaskDelay(2000 / portTICK_PERIOD_MS);
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}
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}
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void app_main(void *ignore)
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{
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ESP_LOGI(RMT_TX_TAG, "Configuring transmitter");
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rmt_tx_int();
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populate_rmt_items();
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ESP_LOGI(RMT_TX_TAG, "Spinning out transmit task");
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xTaskCreatePinnedToCore(&rmt_tx_task, "rmt_tx_task", 4 * 1024, NULL, 5, NULL, 0);
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}
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