Set "Start Discovery" and "End Discovery"

[midnight-studios]

When using set_ssid_callback there seems to be no way to set a timeout for discovery if no match is found. It just scan indefinitely.

On on_discovery_mode_change, there is no a2dp_source.to_str(state) function.

I am reporting these here in discussion, because I am not sure if there is a way to end discovery. I tried 'a2dp_source.end' but this does not seem to stop the discovery.

[pschatzmann]

I committed a correction: so calling end() should work now.
The to_str() is part of BluetoothA2DPCommon so, it is also available for BluetoothA2DPSource

[midnight-studios]

Thanks for your prompt attention to this. Really amazing to see a developer so involved in their project.

I am trying to wrap my head around this, so hopefully the sketch will adequately illustrate an issue I am having.

The sketch is defined to intentionally not find a matching ssid to test discovery initialization and de-initialization. The log indicate towards the discovery successfully scanning for the period of time [esp_bt_gap_start_discovery(ESP_BT_INQ_MODE_GENERAL_INQUIRY, 10, 0);] however on ESP_BT_GAP_DISCOVERY_STOPPED, we call a2dp_source.end() and with your latest commits it exit out of discovery.

A timer defined in loop then starts discovery again, but on any subsequent calls, the bluedroid Initialization fails. And this is what I do not understand.

Here is some data to reproduce:

PLATFORM: Espressif 32 (6.10.0) > Espressif ESP32 Dev Module
HARDWARE: Module: ESP32 WROOM-32, Chip: ESP32 D0WD V3 (Revision v3.1), SP32 240MHz, Memory: 4 MB Flash, 320 KB RAM
framework-arduinoespressif32 @ 3.20017.241212
Dependency Graph
|-- ESP32-A2DP @ 1.8.7
|-- audio-tools @ 1.1.0

// TEST
#include "BluetoothA2DPSource.h"
#include <HardwareSerial.h>
#include "math.h"
#include "Arduino.h"

static char target_device[16] = "FAKE NAME"; // Change to a actual name to test connection

int lastScanTime = 0;
#define c3_frequency  130.81

BluetoothA2DPSource a2dp_source;
const char *m_a2d_disc_state_str[2] = {"Discovery Stopped", "Discovery Started"};

// The supported audio codec in ESP32 A2DP is SBC. SBC audio stream is encoded
// from PCM data normally formatted as 44.1kHz sampling rate, two-channel 16-bit sample data
int32_t get_data_frames(Frame *frame, int32_t frame_count) {
    static float m_time = 0.0;
    float m_amplitude = 10000.0;  // -32,768 to 32,767
    float m_deltaTime = 1.0 / 44100.0;
    float m_phase = 0.0;
    float pi_2 = PI * 2.0;
    // fill the channel data
    for (int sample = 0; sample < frame_count; ++sample) {
        float angle = pi_2 * c3_frequency * m_time + m_phase;
        frame[sample].channel1 = m_amplitude * sin(angle);
        frame[sample].channel2 = frame[sample].channel1;
        m_time += m_deltaTime;
    }
    return frame_count;
}

bool isValid(const char* ssid, esp_bd_addr_t address, int rssi) {

  Serial.println("Discovered Device: " + String(ssid));  

  if (strcmp(target_device, ssid) == 0){
    Serial.println("Target Device identified: " + String(target_device) + "==" + String(ssid) );    
    return true;
  }
  
  return false; // Keep scanning
}

// for esp_a2d_connection_state_t see https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/bluetooth/esp_a2dp.html#_CPPv426esp_a2d_connection_state_t
void connection_state_changed(esp_a2d_connection_state_t state, void *ptr){
  Serial.println(a2dp_source.to_str(state));
}

void bt_discovery_mode_change(esp_bt_gap_discovery_state_t state) {

  Serial.println(" Discovery Mode Changed: " + String(m_a2d_disc_state_str[state]));

  switch(state){

    case ESP_BT_GAP_DISCOVERY_STOPPED: {

        Serial.println("DISCOVERY STOPPED");
        
        a2dp_source.end(true); // End scan

        Serial.println("SOURCE CONNECTED: " + String(a2dp_source.is_connected() ? "TRUE" : "FALSE") );

      break;
    }
    case ESP_BT_GAP_DISCOVERY_STARTED: {
        Serial.println("DISCOVERY STARTED");
      break;
    } 
    default:
      
      break;
  }
}

void setup() {
  Serial.begin(115200);  
  a2dp_source.set_auto_reconnect(false);
  a2dp_source.set_default_bt_mode(ESP_BT_MODE_BTDM);// Depending on what the ESP32 supports
  a2dp_source.set_data_callback_in_frames(get_data_frames);
  a2dp_source.set_volume(100);
  a2dp_source.set_on_connection_state_changed(connection_state_changed);
  a2dp_source.set_discovery_mode_callback(bt_discovery_mode_change);
  a2dp_source.set_ssid_callback(isValid); 
}

void loop() {
  if (millis() - lastScanTime > 5000) {// Check state every 5 seconds
      lastScanTime = millis();
      Serial.println("SOURCE CONNECTED: " + String(a2dp_source.is_connected() ? "TRUE" : "FALSE") );
      Serial.println("DISCOVERY ACTIVE: " + String(a2dp_source.is_discovery_active() ? "TRUE" : "FALSE") );

        if (!a2dp_source.is_connected() && !a2dp_source.is_discovery_active()) { //  Device not found and connected, bluetooth not in discovery mode
        Serial.println("Start Scan....");
        a2dp_source.start(); // Start scan
      }
  }
}

Serial Monitor Output:

SOURCE CONNECTED: FALSE
DISCOVERY ACTIVE: FALSE
Start Scan....
[ 5001][D][BluetoothA2DPSource.cpp:89] start(): [BT_API] start,
[ 5518][D][BluetoothA2DPCommon.cpp:439] app_task_start_up(): [BT_AV] app_task_start_up
[ 5527][I][BluetoothA2DPCommon.cpp:468] app_task_handler(): [BT_AV] app_task_handler
[ 5534][D][BluetoothA2DPSource.cpp:204] bt_app_work_dispatch(): [BT_API] bt_app_work_dispatch event 0x0, param len 0
[ 5545][D][BluetoothA2DPCommon.cpp:481] app_task_handler(): [BT_API] app_task_handler, signal: 0x1, event: 0x0
[ 5555][D][BluetoothA2DPCommon.cpp:500] app_work_dispatched(): [BT_AV] app_work_dispatched
[ 5563][D][BluetoothA2DPSource.cpp:470] av_hdl_stack_evt(): [BT_AV] av_hdl_stack_evt event: 0
[ 5572][I][BluetoothA2DPCommon.cpp:541] set_scan_mode_connectable(): [BT_AV] set_scan_mode_connectable false
[ 5582][I][BluetoothA2DPSource.cpp:519] av_hdl_stack_evt(): [BT_AV] Starting device discovery...
[ 5584][D][BluetoothA2DPSource.cpp:204] bt_app_work_dispatch(): [BT_API] bt_app_work_dispatch event 0x4, param len 16
[ 5601][D][BluetoothA2DPCommon.cpp:481] app_task_handler(): [BT_API] app_task_handler, signal: 0x1, event: 0x4
[ 5601][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 5619][D][BluetoothA2DPCommon.cpp:500] app_work_dispatched(): [BT_AV] app_work_dispatched
[ 5619][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 10
[ 5636][I][BluetoothA2DPSource.cpp:462] app_gap_callback(): [BT_AV] event: 10
[ 5636][I][BluetoothA2DPSource.cpp:585] bt_app_av_sm_hdlr(): [BT_AV] bt_app_av_sm_hdlr state DISCOVERING, evt 0x4
[ 5653][D][BluetoothA2DPSource.cpp:551] process_user_state_callbacks(): [BT_AV] process_user_state_callbacks
[ 5653][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 5671][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 10
[ 5679][I][BluetoothA2DPSource.cpp:462] app_gap_callback(): [BT_AV] event: 10
[ 5686][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 5695][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 10
[ 5703][I][BluetoothA2DPSource.cpp:462] app_gap_callback(): [BT_AV] event: 10
[ 5710][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 5719][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 10
[ 5727][I][BluetoothA2DPSource.cpp:462] app_gap_callback(): [BT_AV] event: 10
[ 5746][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 5755][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 1
Discovery Mode Changed: Discovery Started
DISCOVERY STARTED
[ 5764][I][BluetoothA2DPSource.cpp:369] app_gap_callback(): [BT_AV] Discovery started.
[ 5777][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 5786][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 0
[ 5794][I][BluetoothA2DPSource.cpp:276] filter_inquiry_scan_result(): [BT_AV] Scanned device: 00:7c:2d:b9:b1:dc
[ 5804][I][BluetoothA2DPSource.cpp:282] filter_inquiry_scan_result(): [BT_AV] --Class of Device: 0xc043c
[ 5813][I][BluetoothA2DPSource.cpp:286] filter_inquiry_scan_result(): [BT_AV] --RSSI: -59
[ 5822][I][BluetoothA2DPSource.cpp:304] filter_inquiry_scan_result(): [BT_AV] --Compatiblity: Compatible
[ 5831][I][BluetoothA2DPSource.cpp:306] filter_inquiry_scan_result(): [BT_AV] --Name:

[ 17781][I][BluetoothA2DPSource.cpp:334] filter_inquiry_scan_result(): [BT_AV] --Result: Target device not found
[ 18553][D][BluetoothA2DPCommon.cpp:27] ccall_app_gap_callback(): [BT_AV] ccall_app_gap_callback
[ 18561][D][BluetoothA2DPSource.cpp:341] app_gap_callback(): [BT_AV] app_gap_callback evt 1
Discovery Mode Changed: Discovery Stopped
DISCOVERY STOPPED
[ 18570][I][BluetoothA2DPCommon.cpp:130] end(): [BT_AV] end
[ 18581][D][BluetoothA2DPCommon.cpp:278] clean_last_connection(): [BT_AV] clean_last_connection
[ 18589][D][BluetoothA2DPCommon.cpp:262] set_last_connection(): [BT_AV] set_last_connection: 00:00:00:00:00:00
[ 18599][D][BluetoothA2DPCommon.cpp:266] set_last_connection(): [BT_AV] no change!
[ 18606][I][BluetoothA2DPCommon.cpp:362] log_free_heap(): [BT_AV] Available Heap: 129140
[ 18814][I][BluetoothA2DPCommon.cpp:362] log_free_heap(): [BT_AV] Available Heap: 129108
[ 18822][I][BluetoothA2DPCommon.cpp:179] end(): [BT_AV] disable bluetooth
SOURCE CONNECTED: FALSE
DISCOVERY ACTIVE: FALSE
Start Scan....
[ 20004][D][BluetoothA2DPSource.cpp:89] start(): [BT_API] start,
[ 20015][E][BluetoothA2DPSource.cpp:112] start(): [BT_AV] start initialize bluedroid failed

SOURCE CONNECTED: FALSE
DISCOVERY ACTIVE: FALSE
Start Scan....
[ 25005][D][BluetoothA2DPSource.cpp:89] start(): [BT_API] start,
[ 25016][E][BluetoothA2DPSource.cpp:112] start(): [BT_AV] start initialize bluedroid failed

[pschatzmann]

Just call end() instead of end(true)! Calling end(true) will release all resources, but prevent A2DP to start again!
This is working as documented!

[midnight-studios]

I actually tried both, with and without setting it 'true'

this method:

a2dp_source.end(); // End scan

and this method:

a2dp_source.end(true); // End scan

Using the sketch above, I still get a successful scan for the first time, then call a2dp_source.end();, and when trying to run subsequent scans using a2dp_source.start();, I get

start initialize bluedroid failed.

I even redownloaded the latest files, clean, rebuild and uploaded, but getting the same results. It would be great if this can be reproduced by someone else.

[pschatzmann]

I could reproduce the issue and committed a correction. Here is my test case that I used:

#include "BluetoothA2DPSource.h"

BluetoothA2DPSource a2dp_source;
int j=0;
int32_t get_data(uint8_t *data, int32_t size) {
  memset(data, 0, size);
  if (j++ % 1000 ) Serial.print(".");
  return size;
}

void setup() {
  Serial.begin(115200);

  a2dp_source.set_data_callback(get_data);
  a2dp_source.start("LEXON MINO L");

  /// wait for connection
  uint32_t start = millis();
  while (!a2dp_source.is_connected()) {
    // timout after 10 seconds
    if (millis() - start > 10000) {
      Serial.println("timeout after 10 sec");
      a2dp_source.end();
      break;
    }
    delay(500);
  }
  // re-start connection again
  Serial.println("reconnecting...");
  a2dp_source.start("LEXON MINO L");
}

void loop() {
  delay(1000);  // do nothing
}

[midnight-studios]

Legend!

It has indeed been solved. The only other thing, which is not a big problem, is there is no logic 'a2dp_source.to_str(state)' for the callback function 'a2dp_source.set_discovery_mode_callback(bt_discovery_mode_change)'

Thank you for your attention to this.

[pschatzmann]

OK, I see: I have added const char *to_str(esp_bt_gap_discovery_state_t state);

[midnight-studios]

Thanks again, I think we can close this topic.