Can not connect a second time to a re-created client

[Jeroen88]

MVCE

#include <NimBLEDevice.h>


void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("\n\nStarted");

  BLEDevice::init("ESP32");

  Serial.println("Create");
  NimBLEClient *pClient = BLEDevice::createClient();
  Serial.println("Connecting...");
  bool success = pClient->connect(NimBLEAddress("a4:c1:38:5d:ef:16"));
  if(success) {
    Serial.println("Connected");
    pClient->disconnect();
    Serial.println("Disconnected");

    BLEDevice::deleteClient(pClient);
    Serial.println("Create");
    pClient = BLEDevice::createClient();
    
    Serial.println("Connecting...");
    success = pClient->connect(NimBLEAddress("a4:c1:38:5d:ef:16"));
    if(success) {
      Serial.println("Connected");
      pClient->disconnect();
      Serial.println("Disconnected");
    }
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}

Logging:

Started
I NimBLEDevice: "BLE Host Task Started"
I NimBLEDevice: "NimBle host synced."
Create
Connecting...
D NimBLEClient: ">> connect(a4:c1:38:5d:ef:16)"
D FreeRTOS: "Semaphore taking: name: OpenEvt (0x3ffc8870), owner: <N/A> for connect"
D FreeRTOS: "Semaphore taken:  name: OpenEvt (0x3ffc8870), owner: connect"
D FreeRTOS: ">> wait: Semaphore waiting: name: OpenEvt (0x3ffc8870), owner: connect for connect"
D NimBLEClient: "Got Client event "
D NimBLEClient: "Connection established"
D FreeRTOS: "Semaphore giving: name: OpenEvt (0x3ffc8870), owner: connect"
D FreeRTOS: "<< wait: Semaphore released: name: OpenEvt (0x3ffc8870), owner: <N/A>"
D NimBLEClient: "Refreshing Services for: (a4:c1:38:5d:ef:16)"
D NimBLEClient: ">> deleteServices"
D NimBLEClient: "<< deleteServices"
D NimBLEClientCallbacks: "onConnect: default"
D NimBLEClient: "<< connect()"
Connected
D NimBLEClient: ">> disconnect()"
D NimBLEClient: "<< disconnect()"
Disconnected
D NimBLEClient: ">> deleteServices"
D NimBLEClient: "<< deleteServices"
Create
Connecting...
D NimBLEClient: ">> connect(a4:c1:38:5d:ef:16)"
D FreeRTOS: "Semaphore taking: name: OpenEvt (0x3ffc8870), owner: <N/A> for connect"
D FreeRTOS: "Semaphore taken:  name: OpenEvt (0x3ffc8870), owner: connect"
D FreeRTOS: ">> wait: Semaphore waiting: name: OpenEvt (0x3ffc8870), owner: connect for connect"
D NimBLEClient: "Got Client event "
D NimBLEClient: "Got Client event "

... and then just "hangs"

[Staars]

This reminds of my last weekend, where I finally was "sure" that my ESP32 was broken.

For me the solution was to erase the flash , which seemed to have solved it. In the end I erased it basically before every upload.

What IDE are you using? If you are using some kind of caching mechanism, you might need to delete the compiler cache too.

[Jeroen88]

I had a "broken" ESP32 too a few days ago, put it apart, I have not thrown it away yet. I'll try to erase the flash to see if that brings it back to life.

But this is another issue. I can reset to run the sketch again. I can re-flash and start the program over again. But is won't get passed the second connect(). As you can see in the logging, while connecting the first time it logs:

D NimBLEClient: "Got Client event "
D NimBLEClient: "Connection established"

and the second time it logs:

D NimBLEClient: "Got Client event "
D NimBLEClient: "Got Client event "

and then waits forever...

Most of the time, also this time, I use the Arduino IDE, 1.8.10 (that is the one but last I believe). Every now and then I use pio.

[h2zero]

Turn on event code strings to see what

D NimBLEClient: "Got Client event "
D NimBLEClient: "Got Client event "

actually are.

Looks like you're hanging on a semaphore, or the stack is getting stuck because the peripheral has not disconnected yet. Try putting a delay of 100ms or so between deleting and creating the client.

[Jeroen88]

Logging now:

Started
I NimBLEDevice: "BLE Host Task Started"
I NimBLEDevice: "NimBle host synced."
Create
Connecting...
D NimBLEClient: ">> connect(a4:c1:38:5d:ef:16)"
D FreeRTOS: "Semaphore taking: name: OpenEvt (0x3ffc88fc), owner: <N/A> for connect"
D FreeRTOS: "Semaphore taken:  name: OpenEvt (0x3ffc88fc), owner: connect"
D FreeRTOS: ">> wait: Semaphore waiting: name: OpenEvt (0x3ffc88fc), owner: connect for connect"
D NimBLEClient: "Got Client event BLE_GAP_EVENT_CONNECT "
D NimBLEClient: "Connection established"
D FreeRTOS: "Semaphore giving: name: OpenEvt (0x3ffc88fc), owner: connect"
D FreeRTOS: "<< wait: Semaphore released: name: OpenEvt (0x3ffc88fc), owner: <N/A>"
D NimBLEClient: "Refreshing Services for: (a4:c1:38:5d:ef:16)"
D NimBLEClient: ">> deleteServices"
D NimBLEClient: "<< deleteServices"
D NimBLEClientCallbacks: "onConnect: default"
D NimBLEClient: "<< connect()"
Connected
D NimBLEClient: ">> disconnect()"
D NimBLEClient: "<< disconnect()"
Disconnected
D NimBLEClient: ">> deleteServices"
D NimBLEClient: "<< deleteServices"
Create
Connecting...
D NimBLEClient: ">> connect(a4:c1:38:5d:ef:16)"
D FreeRTOS: "Semaphore taking: name: OpenEvt (0x3ffc88fc), owner: <N/A> for connect"
D FreeRTOS: "Semaphore taken:  name: OpenEvt (0x3ffc88fc), owner: connect"
D FreeRTOS: ">> wait: Semaphore waiting: name: OpenEvt (0x3ffc88fc), owner: connect for connect"
D NimBLEClient: "Got Client event BLE_GAP_EVENT_MTU"
D NimBLEClient: "Got Client event BLE_GAP_EVENT_DISCONNECT"

I think the issue is indeed that BLE_GAP_EVENT_DISCONNECT arrives AFTER calling connect() again.

I think disconnect() should wait for this event...!

[Jeroen88]

Adding a 200 ms delay between createClient() and connect() solves the problem, 100 ms is too short. Still I think disconnect() should wait for the event.

[Staars]

Adding a 200 ms delay between createClient() and connect() solves the problem, 100 ms is too short. Still I think disconnect() should wait for the event.

Interesting observation, I will test this too.

[h2zero]

What is the purpose of doing this? It seems odd to me to create a client object delete it and create another in such a short time, why not just reuse the client object?

Still I think disconnect() should wait for the event.

That would unnecessarily slow down other applications, if you really need to know the client is disconnected there is a callback for that.

[Jeroen88]

In the integration I am creating several devices are read out independently. Most don't need a connection, some do. I just want to use the functionality that is there. Also, I think it should always work

Could you give me some directions how to check if the client has disconnected? The function isDisconnected() does not do this job

[chegewara]

For me the solution was to erase the flash , which seemed to have solved it. In the end I erased it basically before every upload.

This is must when you are building bluetooth app.

[chegewara]

D FreeRTOS: ">> wait: Semaphore waiting: name: OpenEvt (0x3ffc88fc), owner: connect for connect"
D NimBLEClient: "Got Client event BLE_GAP_EVENT_MTU"
D NimBLEClient: "Got Client event BLE_GAP_EVENT_DISCONNECT"

This may have happen when there is no successful connection, maybe except MTU exchange, because this requires full connection established, unless MTU is called too early (in wrong place).

[Staars]

I have learned this …. after several hours :) (It was not obvious to me before)

…

Am 29.05.2020 um 17:30 schrieb chegewara ***@***.***>: For me the solution was to erase the flash , which seemed to have solved it. In the end I erased it basically before every upload. This is must when you are building bluetooth app. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#65 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABJ2EZC63EH42R77TCMPHLLRT7IKLANCNFSM4NNDS4XA>.

[h2zero]

This issue was just resolved in commit 4c798fe.

[Jeroen88]

This issue was just resolved in commit 4c798fe.

I can confirm that. Thank you @h2zero!