esp32: support audio playback via btstack_audio_esp32.c

port/esp32/README.md

@@ -50,6 +50,20 @@ The sdkconfig of the example template disables the original Bluedroid stack by d
 
 There are different issues in the Bluetooth Controller of the ESP32 that is provided in binary. We've submitted appropriate issues on the GitHub Issues page here: https://github.com/espressif/esp-idf/issues/created_by/mringwal
 
+### Audio playback
+
+Audio playback is implemented by `btstack_audio_esp32.c`. It assumes an I2S Codec connected as follows:
+	
+ESP32 pin | I2S Pin
+----------|---------
+GPIO25    | LRCK
+GPIO26    | BCLK
+GPIO22    | DATA
+
+We've used the MAX98357A on the [Adafruit breakout board](https://www.adafruit.com/product/3006). The simplest example is the mod_player, which plays back an 8 kB sound file and the a2dp_sink_demo implements a basic Bluetooth loudspeaker.
+
+Audio input via I2S or ADC is not supported yet. We might have a look at it when [HFP/SCO via VHCI](https://github.com/espressif/esp-idf/issues/1118) is working on the ESP32.
+
 ### Multi-Threading
 
 BTstack is not thread-safe, but you're using a multi-threading OS. Any function that is called from BTstack, e.g. packet handlers, can directly call into BTstack without issues. For other situations, you need to provide some general 'do BTstack tasks' function and trigger BTstack to execute it on its own thread.

port/esp32/components/btstack/btstack_audio_esp32.c

@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) 2018 BlueKitchen GmbH
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the copyright holders nor the names of
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ * 4. Any redistribution, use, or modification is done solely for
+ *    personal benefit and not for any commercial purpose or for
+ *    monetary gain.
+ *
+ * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
+ * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * Please inquire about commercial licensing options at 
+ * contact@bluekitchen-gmbh.com
+ *
+ */
+
+#define __BTSTACK_FILE__ "btstack_audio_esp32.c"
+
+/*
+ *  btstack_audio_esp32.c
+ *
+ *  Implementation of btstack_audio.h using polling ESP32 I2S driver
+ *
+ */
+
+#include "btstack_config.h"
+#include "btstack_debug.h"
+#include "btstack_audio.h"
+#include "btstack_run_loop.h"
+#include "hal_audio.h"
+
+#include "freertos/FreeRTOS.h"
+#include "driver/i2s.h"
+
+#define DRIVER_POLL_INTERVAL_MS          5
+#define DMA_BUFFER_COUNT                 2
+#define DMA_BUFFER_SAMPLES               512
+#define BYTES_PER_SAMPLE_STEREO          4
+
+static int num_channels;
+static int bytes_per_sample;
+
+// client
+static void (*playback_callback)(int16_t * buffer, uint16_t num_samples);
+static void (*recording_callback)(const int16_t * buffer, uint16_t num_samples);
+
+// timer to fill output ring buffer
+static btstack_timer_source_t  driver_timer;
+
+// queue for TX done events
+static QueueHandle_t i2s_event_queue;
+
+static int i2s_num = I2S_NUM_0;
+
+static void fill_buffer(void){
+    size_t bytes_written;
+    uint8_t buffer[DMA_BUFFER_SAMPLES * BYTES_PER_SAMPLE_STEREO];
+    (*playback_callback)((int16_t*)buffer, DMA_BUFFER_SAMPLES);
+    i2s_write(i2s_num, buffer, DMA_BUFFER_SAMPLES * bytes_per_sample, &bytes_written, portMAX_DELAY);
+}
+
+static void driver_timer_handler(btstack_timer_source_t * ts){
+
+    // playback buffer ready to fill
+    if (playback_callback){
+        // read from i2s event queue
+        i2s_event_t i2s_event;
+        if( xQueueReceive( i2s_event_queue, &i2s_event, 0) ){
+            // fill buffer when DMA buffer was sent            
+            if (i2s_event.type == I2S_EVENT_TX_DONE){
+                fill_buffer();
+            }
+        }
+    }
+
+    // recording buffer ready to process
+    if (recording_callback){
+    }    
+
+    // re-set timer
+    btstack_run_loop_set_timer(ts, DRIVER_POLL_INTERVAL_MS);
+    btstack_run_loop_add_timer(ts);
+}
+
+static int btstack_audio_esp32_init(
+    uint8_t channels,
+    uint32_t samplerate, 
+    void (*playback)(int16_t * buffer, uint16_t num_samples),
+    void (*recording)(const int16_t * buffer, uint16_t num_samples)
+){
+    playback_callback  = playback;
+    recording_callback = recording;
+    num_channels       = channels;
+    bytes_per_sample   = channels * 2;  // 16-bit
+
+    i2s_config_t config = 
+    {
+        .mode                 = I2S_MODE_MASTER | I2S_MODE_TX, // Playback only
+        .sample_rate          = samplerate,
+        .bits_per_sample      = I2S_BITS_PER_SAMPLE_16BIT,
+        .channel_format       = I2S_CHANNEL_FMT_RIGHT_LEFT,
+        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
+        .dma_buf_count        = DMA_BUFFER_COUNT,              // Number of DMA buffers. Max 128.
+        .dma_buf_len          = DMA_BUFFER_SAMPLES,            // Size of each DMA buffer in samples. Max 1024.
+        .intr_alloc_flags     = ESP_INTR_FLAG_LEVEL1
+    };
+    i2s_pin_config_t pins = 
+    {
+        .bck_io_num           = 26,
+        .ws_io_num            = 25,
+        .data_out_num         = 22,
+        .data_in_num          = I2S_PIN_NO_CHANGE
+    };
+
+    i2s_driver_install(i2s_num, &config, DMA_BUFFER_COUNT, &i2s_event_queue);
+    i2s_set_pin(i2s_num, &pins);
+    i2s_zero_dma_buffer(i2s_num);
+
+    return 0;
+}
+
+static void btstack_audio_esp32_start_stream(void){
+
+    if (playback_callback){
+        // pre-fill HAL buffers
+        log_info("start stream");
+        uint16_t i;
+        for (i=0;i<DMA_BUFFER_COUNT;i++){
+            fill_buffer();
+        }
+    }
+
+    // TODO: setup input
+
+    // start i2s
+    i2s_start(i2s_num);
+
+    // start timer
+    btstack_run_loop_set_timer_handler(&driver_timer, &driver_timer_handler);
+    btstack_run_loop_set_timer(&driver_timer, DRIVER_POLL_INTERVAL_MS);
+    btstack_run_loop_add_timer(&driver_timer);
+}
+
+static void btstack_audio_esp32_close(void){
+    // stop timer
+    btstack_run_loop_remove_timer(&driver_timer);
+
+    // stop i2s
+     i2s_stop(i2s_num);
+
+     // uninstall driver
+     i2s_driver_uninstall(i2s_num);
+}
+
+static const btstack_audio_t btstack_audio_esp32 = {
+    /* int (*init)(..);*/                                       &btstack_audio_esp32_init,
+    /* void (*start_stream(void));*/                            &btstack_audio_esp32_start_stream,
+    /* void (*close)(void); */                                  &btstack_audio_esp32_close
+};
+
+const btstack_audio_t * btstack_audio_esp32_get_instance(void){
+    return &btstack_audio_esp32;
+}

port/esp32/components/btstack/main.c

@@ -57,6 +57,7 @@
 #include "hci_dump.h"
 #include "esp_bt.h"
 #include "btstack_debug.h"
+#include "btstack_audio.h"
 
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
@@ -384,6 +385,9 @@ int app_main(void){
     hci_event_callback_registration.callback = &packet_handler;
     hci_add_event_handler(&hci_event_callback_registration);
 
+    // setup i2s audio
+    btstack_audio_set_instance(btstack_audio_esp32_get_instance());
+
     btstack_main(0, NULL);
 
     printf("BTstack: execute run loop\n");