audio: add internal dac and pdm output mode

Author: redchenjs

main/src/device/i2s.c

@@ -10,30 +10,40 @@
 
 void i2s0_init(void)
 {
-    int use_apll = 0;
     esp_chip_info_t chip_info;
     esp_chip_info(&chip_info);
-    // Don't use apll on rev0 chips
-    if (chip_info.revision != 0) {
-        use_apll = 1;
-    }
     i2s_config_t i2s_config = {
+#if defined(CONFIG_I2S_OUTPUT_INTERNAL_DAC)
+        .mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN,
+        .communication_format = I2S_COMM_FORMAT_I2S_MSB,
+        .use_apll = 0,
+#elif defined(CONFIG_I2S_OUTPUT_PDM)
+        .mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_PDM,
+        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
+        .use_apll = 0,
+#else
         .mode = I2S_MODE_MASTER | I2S_MODE_TX,                                  // Only TX
+        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
+        .use_apll = chip_info.revision,                                         // Don't use apll on rev0 chips
+#endif
         .sample_rate = 44100,
-        .bits_per_sample = 16,                                              
+        .bits_per_sample = 16,
         .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           // 2-channels
-        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
         .dma_buf_count = 8,
         .dma_buf_len = 64,
-        .use_apll = use_apll,
         .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1                                // Interrupt level 1
     };
+    i2s_driver_install(0, &i2s_config, 0, NULL);
+#if defined(CONFIG_I2S_OUTPUT_INTERNAL_DAC) || defined(CONFIG_I2S_OUTPUT_PDM)
+    i2s_set_pin(0, NULL);
+    i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);
+#else
     i2s_pin_config_t pin_config = {
         .bck_io_num = 22,
         .ws_io_num = 21,
         .data_out_num = 19,
         .data_in_num = -1                                                       // Not used
     };
-    i2s_driver_install(0, &i2s_config, 0, NULL);
     i2s_set_pin(0, &pin_config);
+#endif
 }

main/src/tasks/bt_av.c

@@ -54,7 +54,43 @@ void bt_av_a2d_cb(esp_a2d_cb_event_t event, esp_a2d_cb_param_t *param)
 /* cb with decoded samples */
 void bt_av_a2d_data_cb(const uint8_t *data, uint32_t len)
 {
-    i2s_write_bytes(0, (const char *)data, len, portMAX_DELAY);
+    TickType_t max_wait = 20 / portTICK_PERIOD_MS;
+#if defined(CONFIG_I2S_OUTPUT_INTERNAL_DAC)
+    uint8_t num_channel = 2;
+    uint8_t bytes_per_sample = sizeof(uint8_t) * 2;     // 16-bit per channel
+    uint8_t stride = bytes_per_sample * num_channel;
+
+    // pointer to left / right sample position
+    char *ptr_l = (char *)data;
+    char *ptr_r = (char *)data + stride;
+
+    int bytes_pushed = 0;
+    for (int i = 0; i < len/stride; i++) {
+        // assume 16 bit src bit_depth
+        short left  = *(short *) ptr_l;
+        short right = *(short *) ptr_r;
+
+        // The built-in DAC wants unsigned samples, so we shift the range
+        // from -32768-32767 to 0-65535.
+        left  = left  + 0x8000;
+        right = right + 0x8000;
+
+        uint32_t sample = (uint16_t) left;
+        sample = (sample << 16 & 0xffff0000) | ((uint16_t) right);
+
+        bytes_pushed = i2s_push_sample(0, (const char*) &sample, max_wait);
+
+        // DMA buffer full - retry
+        if (bytes_pushed == 0) {
+            i--;
+        } else {
+            ptr_r += stride;
+            ptr_l += stride;
+        }
+    }
+#else
+    i2s_write_bytes(0, (const char *)data, len, max_wait);
+#endif
 }
 
 void bt_av_rc_ct_cb(esp_avrc_ct_cb_event_t event, esp_avrc_ct_cb_param_t *param)

main/src/tasks/mp3_player.c

@@ -84,6 +84,8 @@ void mp3_player_task(void *pvParameters)
 /* render callback for the libmad synth */
 void render_sample_block(short *sample_buff_ch0, short *sample_buff_ch1, int num_samples, unsigned int num_channels)
 {
+    TickType_t max_wait = 20 / portTICK_PERIOD_MS;
+
     // pointer to left / right sample position
     char *ptr_l = (char*) sample_buff_ch0;
     char *ptr_r = (char*) sample_buff_ch1;
@@ -94,12 +96,26 @@ void render_sample_block(short *sample_buff_ch0, short *sample_buff_ch1, int num
     }
 
     int bytes_pushed = 0;
-    TickType_t max_wait = 20 / portTICK_PERIOD_MS; // portMAX_DELAY = bad idea
     for (int i = 0; i < num_samples; i++) {
+#if defined(CONFIG_I2S_OUTPUT_INTERNAL_DAC)
+        // assume 16 bit src bit_depth
+        short left  = *(short *) ptr_l;
+        short right = *(short *) ptr_r;
+
+        // The built-in DAC wants unsigned samples, so we shift the range
+        // from -32768-32767 to 0-65535.
+        left  = left  + 0x8000;
+        right = right + 0x8000;
+
+        uint32_t sample = (uint16_t) left;
+        sample = (sample << 16 & 0xffff0000) | ((uint16_t) right);
+
+        bytes_pushed = i2s_push_sample(0, (const char*) &sample, max_wait);
+#else
         /* low - high / low - high */
         const char samp32[4] = {ptr_l[0], ptr_l[1], ptr_r[0], ptr_r[1]};
         bytes_pushed = i2s_push_sample(0, (const char*) &samp32, max_wait);
-
+#endif
         // DMA buffer full - retry
         if (bytes_pushed == 0) {
             i--;