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SPDIF example1
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‎examples/sandbox/streams-generator-spdif1/spdif.c

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/*
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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 "driver/i2s.h"
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#ifdef CONFIG_SPDIF_DATA_PIN
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#define SPDIF_DATA_PIN CONFIG_SPDIF_DATA_PIN
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#else
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#define SPDIF_DATA_PIN 23
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#endif
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#define I2S_NUM (0)
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#define I2S_BITS_PER_SAMPLE (32)
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#define I2S_CHANNELS 2
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#define BMC_BITS_PER_SAMPLE 64
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#define BMC_BITS_FACTOR (BMC_BITS_PER_SAMPLE / I2S_BITS_PER_SAMPLE)
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#define SPDIF_BLOCK_SAMPLES 192
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#define SPDIF_BUF_DIV 2 // double buffering
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#define DMA_BUF_COUNT 2
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#define DMA_BUF_LEN (SPDIF_BLOCK_SAMPLES * BMC_BITS_PER_SAMPLE / I2S_BITS_PER_SAMPLE / SPDIF_BUF_DIV)
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#define I2S_BUG_MAGIC (26 * 1000 * 1000) // magic number for avoiding I2S bug
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#define SPDIF_BLOCK_SIZE (SPDIF_BLOCK_SAMPLES * (BMC_BITS_PER_SAMPLE/8) * I2S_CHANNELS)
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#define SPDIF_BUF_SIZE (SPDIF_BLOCK_SIZE / SPDIF_BUF_DIV)
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#define SPDIF_BUF_ARRAY_SIZE (SPDIF_BUF_SIZE / sizeof(uint32_t))
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static uint32_t spdif_buf[SPDIF_BUF_ARRAY_SIZE];
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static uint32_t *spdif_ptr;
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/*
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* 8bit PCM to 16bit BMC conversion table, LSb first, 1 end
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*/
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static const int16_t bmc_tab[256] = {
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0x3333, 0xb333, 0xd333, 0x5333, 0xcb33, 0x4b33, 0x2b33, 0xab33,
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0xcd33, 0x4d33, 0x2d33, 0xad33, 0x3533, 0xb533, 0xd533, 0x5533,
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0xccb3, 0x4cb3, 0x2cb3, 0xacb3, 0x34b3, 0xb4b3, 0xd4b3, 0x54b3,
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0x32b3, 0xb2b3, 0xd2b3, 0x52b3, 0xcab3, 0x4ab3, 0x2ab3, 0xaab3,
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0xccd3, 0x4cd3, 0x2cd3, 0xacd3, 0x34d3, 0xb4d3, 0xd4d3, 0x54d3,
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0x32d3, 0xb2d3, 0xd2d3, 0x52d3, 0xcad3, 0x4ad3, 0x2ad3, 0xaad3,
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0x3353, 0xb353, 0xd353, 0x5353, 0xcb53, 0x4b53, 0x2b53, 0xab53,
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0xcd53, 0x4d53, 0x2d53, 0xad53, 0x3553, 0xb553, 0xd553, 0x5553,
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0xcccb, 0x4ccb, 0x2ccb, 0xaccb, 0x34cb, 0xb4cb, 0xd4cb, 0x54cb,
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0x32cb, 0xb2cb, 0xd2cb, 0x52cb, 0xcacb, 0x4acb, 0x2acb, 0xaacb,
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0x334b, 0xb34b, 0xd34b, 0x534b, 0xcb4b, 0x4b4b, 0x2b4b, 0xab4b,
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0xcd4b, 0x4d4b, 0x2d4b, 0xad4b, 0x354b, 0xb54b, 0xd54b, 0x554b,
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0x332b, 0xb32b, 0xd32b, 0x532b, 0xcb2b, 0x4b2b, 0x2b2b, 0xab2b,
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0xcd2b, 0x4d2b, 0x2d2b, 0xad2b, 0x352b, 0xb52b, 0xd52b, 0x552b,
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0xccab, 0x4cab, 0x2cab, 0xacab, 0x34ab, 0xb4ab, 0xd4ab, 0x54ab,
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0x32ab, 0xb2ab, 0xd2ab, 0x52ab, 0xcaab, 0x4aab, 0x2aab, 0xaaab,
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0xcccd, 0x4ccd, 0x2ccd, 0xaccd, 0x34cd, 0xb4cd, 0xd4cd, 0x54cd,
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0x32cd, 0xb2cd, 0xd2cd, 0x52cd, 0xcacd, 0x4acd, 0x2acd, 0xaacd,
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0x334d, 0xb34d, 0xd34d, 0x534d, 0xcb4d, 0x4b4d, 0x2b4d, 0xab4d,
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0xcd4d, 0x4d4d, 0x2d4d, 0xad4d, 0x354d, 0xb54d, 0xd54d, 0x554d,
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0x332d, 0xb32d, 0xd32d, 0x532d, 0xcb2d, 0x4b2d, 0x2b2d, 0xab2d,
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0xcd2d, 0x4d2d, 0x2d2d, 0xad2d, 0x352d, 0xb52d, 0xd52d, 0x552d,
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0xccad, 0x4cad, 0x2cad, 0xacad, 0x34ad, 0xb4ad, 0xd4ad, 0x54ad,
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0x32ad, 0xb2ad, 0xd2ad, 0x52ad, 0xcaad, 0x4aad, 0x2aad, 0xaaad,
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0x3335, 0xb335, 0xd335, 0x5335, 0xcb35, 0x4b35, 0x2b35, 0xab35,
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0xcd35, 0x4d35, 0x2d35, 0xad35, 0x3535, 0xb535, 0xd535, 0x5535,
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0xccb5, 0x4cb5, 0x2cb5, 0xacb5, 0x34b5, 0xb4b5, 0xd4b5, 0x54b5,
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0x32b5, 0xb2b5, 0xd2b5, 0x52b5, 0xcab5, 0x4ab5, 0x2ab5, 0xaab5,
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0xccd5, 0x4cd5, 0x2cd5, 0xacd5, 0x34d5, 0xb4d5, 0xd4d5, 0x54d5,
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0x32d5, 0xb2d5, 0xd2d5, 0x52d5, 0xcad5, 0x4ad5, 0x2ad5, 0xaad5,
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0x3355, 0xb355, 0xd355, 0x5355, 0xcb55, 0x4b55, 0x2b55, 0xab55,
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0xcd55, 0x4d55, 0x2d55, 0xad55, 0x3555, 0xb555, 0xd555, 0x5555,
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};
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// BMC preamble
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#define BMC_B 0x33173333 // block start
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#define BMC_M 0x331d3333 // left ch
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#define BMC_W 0x331b3333 // right ch
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#define BMC_MW_DIF (BMC_M ^ BMC_W)
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#define SYNC_OFFSET 2 // byte offset of SYNC
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#define SYNC_FLIP ((BMC_B ^ BMC_M) >> (SYNC_OFFSET * 8))
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// initialize S/PDIF buffer
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static void spdif_buf_init(void)
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{
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int i;
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uint32_t bmc_mw = BMC_W;
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for (i = 0; i < SPDIF_BUF_ARRAY_SIZE; i += 2) {
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spdif_buf[i] = bmc_mw ^= BMC_MW_DIF;
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}
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}
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// initialize I2S for S/PDIF transmission
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void spdif_init(int rate)
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{
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int sample_rate = rate * BMC_BITS_FACTOR;
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int bclk = sample_rate * I2S_BITS_PER_SAMPLE * I2S_CHANNELS;
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int mclk = (I2S_BUG_MAGIC / bclk) * bclk; // use mclk for avoiding I2S bug
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i2s_config_t i2s_config = {
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.mode = I2S_MODE_MASTER | I2S_MODE_TX,
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.sample_rate = sample_rate,
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.bits_per_sample = I2S_BITS_PER_SAMPLE,
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.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
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.communication_format = I2S_COMM_FORMAT_I2S,
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.intr_alloc_flags = 0,
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.dma_buf_count = DMA_BUF_COUNT,
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.dma_buf_len = DMA_BUF_LEN,
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.use_apll = true,
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.tx_desc_auto_clear = true,
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.fixed_mclk = mclk, // avoiding I2S bug
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};
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i2s_pin_config_t pin_config = {
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.bck_io_num = -1,
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.ws_io_num = -1,
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.data_out_num = SPDIF_DATA_PIN,
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.data_in_num = -1,
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};
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ESP_ERROR_CHECK(i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL));
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ESP_ERROR_CHECK(i2s_set_pin(I2S_NUM, &pin_config));
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// initialize S/PDIF buffer
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spdif_buf_init();
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spdif_ptr = spdif_buf;
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}
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// write audio data to I2S buffer
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void spdif_write(const void *src, size_t size)
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{
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const uint8_t *p = src;
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while (p < (uint8_t *)src + size) {
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// convert PCM 16bit data to BMC 32bit pulse pattern
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*(spdif_ptr + 1) = (uint32_t)(((bmc_tab[*p] << 16) ^ bmc_tab[*(p + 1)]) << 1) >> 1;
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p += 2;
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spdif_ptr += 2; // advance to next audio data
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if (spdif_ptr >= &spdif_buf[SPDIF_BUF_ARRAY_SIZE]) {
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size_t i2s_write_len;
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// set block start preamble
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((uint8_t *)spdif_buf)[SYNC_OFFSET] ^= SYNC_FLIP;
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i2s_write(I2S_NUM, spdif_buf, sizeof(spdif_buf), &i2s_write_len, portMAX_DELAY);
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spdif_ptr = spdif_buf;
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}
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}
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}
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// change S/PDIF sample rate
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void spdif_set_sample_rates(int rate)
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{
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// uninstall and reinstall I2S driver for avoiding I2S bug
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i2s_driver_uninstall(I2S_NUM);
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spdif_init(rate);
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}

‎examples/sandbox/streams-generator-spdif1/spdif.h

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/*
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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 <stdint.h>
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#include <sys/types.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* initialize S/PDIF driver
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* rate: sampling rate, 44100Hz, 48000Hz etc.
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*/
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void spdif_init(int rate);
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/*
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* send PCM data to S/PDIF transmitter
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* src: pointer to 16bit PCM stereo data
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* size: number of data bytes
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*/
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void spdif_write(const void *src, size_t size);
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/*
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* change sampling rate
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* rate: sampling rate, 44100Hz, 48000Hz etc.
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*/
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void spdif_set_sample_rates(int rate);
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#ifdef __cplusplus
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}
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#endif

‎examples/sandbox/streams-generator-spdif1/streams-generator-spdif1.ino

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/**
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* @file streams-generator-i2s.ino
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* @author Phil Schatzmann
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* @brief Test
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* @copyright GPLv3
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*/
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#include "AudioTools.h"
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#include "spdif.h"
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using namespace audio_tools;
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typedef int16_t sound_t; // sound will be represented as int16_t (with 2 bytes)
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uint16_t sample_rate=44100;
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uint8_t channels = 2; // The stream will have 2 channels
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SineWaveGenerator<sound_t> sineWave(32000); // subclass of SoundGenerator with max amplitude of 32000
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GeneratedSoundStream<sound_t> sound(sineWave); // Stream generated from sine wave
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uint8_t buffer[1024];
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// Arduino Setup
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void setup(void) {
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// Open Serial
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Serial.begin(115200);
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AudioLogger::instance().begin(Serial, AudioLogger::Info);
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// start I2S
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Serial.println("starting SPDIF...");
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auto config = out.defaultConfig();
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config.sample_rate = sample_rate;
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config.channels = channels;
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config.pin_data = 23;
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out.begin(config);
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// Setup sine wave
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sineWave.begin(channels, sample_rate, N_B4);
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Serial.println("started...");
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spdif_init(sample_rate);
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}
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// Arduino loop - copy sound to out
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void loop() {
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int read = sound.readBytes(buffer, 1024);
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spdif_write(buffer, read);
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}

‎examples/sandbox/streams-generator-spdif_hex/out1.txt

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12:51:13.857 -> 33 33 1D 33 33 B3 32 55 - 33 33 1B 33 33 B3 32 55
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12:51:13.857 -> 33 33 1D 33 55 CD CA 34 - 33 33 1B 33 55 CD CA 34
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12:51:13.891 -> 33 33 1D 33 55 33 33 53 - 33 33 1B 33 55 33 33 53
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12:51:13.891 -> 33 33 1D 33 D5 54 4B 4B - 33 33 1B 33 D5 54 4B 4B
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12:51:13.891 -> 33 33 1D 33 B5 2A 35 2B - 33 33 1B 33 B5 2A 35 2B
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12:51:13.891 -> 33 33 1D 33 B5 D4 D4 2C - 33 33 1B 33 B5 D4 D4 2C
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12:51:13.891 -> 33 33 1D 33 35 D5 AC 2C - 33 33 1B 33 35 D5 AC 2C
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12:51:13.891 -> 33 33 1D 33 35 2B CB 2C - 33 33 1B 33 35 2B CB 2C
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12:51:13.891 -> 33 33 1D 33 AD 2A 4D 2D - 33 33 1B 33 AD 2A 4D 2D
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12:51:13.891 -> 33 33 1D 33 AD 54 CB 54 - 33 33 1B 33 AD 54 CB 54
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12:51:13.924 -> 33 33 1D 33 AD CC 34 55 - 33 33 1B 33 AD CC 34 55
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12:51:13.924 -> 33 33 1D 33 2D 4D AD 52 - 33 33 1B 33 2D 4D AD 52
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12:51:13.924 -> 33 33 1D 33 2D 53 4D 4B - 33 33 1B 33 2D 53 4D 4B
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12:51:13.924 -> 33 33 1D 33 4D B5 2A 4B - 33 33 1B 33 4D B5 2A 4B
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12:51:13.924 -> 33 33 1D 33 4D CD 52 33 - 33 33 1B 33 4D CD 52 33
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12:51:13.924 -> 33 33 1D 33 4D 53 55 55 - 33 33 1B 33 4D 53 55 55
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12:51:13.924 -> 33 33 1D 33 CD AA 4A 2B - 33 33 1B 33 CD AA 4A 2B
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12:51:13.957 -> 33 33 1D 33 CD CA AC 4A - 33 33 1B 33 CD CA AC 4A
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12:51:13.957 -> 33 33 1D 33 CD B2 AC 34 - 33 33 1B 33 CD B2 AC 34
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12:51:13.957 -> 33 33 1D 33 CD D4 CA 34 - 33 33 1B 33 CD D4 CA 34
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12:51:13.957 -> 33 33 1D 33 CD 34 D5 4A - 33 33 1B 33 CD 34 D5 4A
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12:51:13.957 -> 33 33 1D 33 CD AC 52 53 - 33 33 1B 33 CD AC 52 53
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12:51:13.957 -> 33 33 1D 33 CD AC 4C 4B - 33 33 1B 33 CD AC 4C 4B
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12:51:13.957 -> 33 33 1D 33 CD AC 4C 4B - 33 33 1B 33 CD AC 4C 4B
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12:51:13.991 -> 33 33 1D 33 CD AC 52 4B - 33 33 1B 33 CD AC 52 4B
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12:51:13.991 -> 33 33 1D 33 CD 34 55 33 - 33 33 1B 33 CD 34 55 33
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12:51:13.991 -> 33 33 1D 33 CD D4 CA 32 - 33 33 1B 33 CD D4 CA 32
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12:51:13.991 -> 33 33 1D 33 CD B2 AC 4A - 33 33 1B 33 CD B2 AC 4A

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