Problems with the db discovery module

RE: Problems with the db discovery module

anthony — Thu, 17 Nov 2016 17:30:43 GMT

Hi,

I think I have the same error, but even changing the project with rigth UUID names of the service and characteristic it doesn't work. The function "ble_nus_c_rx_notif_enable" returns a NRF_ERROR_INVALID_STATE, because "p_ble_nus_c->handles.nus_rx_cccd_handle == BLE_GATT_HANDLE_INVALID" is true. I'va done my peripheral starting from the ble_app_hrs project and following the tutorial to do my own service and for the central I use the ble_app_uart_c project. How do we update the CCCD handle? For the peripheral I use a pca10028 and for the central a pca10031, both project from the SDK11.

RE: Problems with the db discovery module

MartinBL — Thu, 12 May 2016 07:16:28 GMT

Happy to help. Glad we worked it out.

RE: Problems with the db discovery module

Revo — Wed, 11 May 2016 12:52:52 GMT

Thanks this totally works now. I will make you a monument. wonderful!!!

RE: Problems with the db discovery module

MartinBL — Wed, 11 May 2016 12:42:12 GMT

Hi,

I think maybe I have figured it out. The reason why it was hard to debug was that you and I have been using different ble_nus_c.c files (since this file is not placed in the project folder). You have modified yours, but I have been using the original. When I tried the one you have uploaded I see the same behaviour as you.

It is not a regular disconnect you see, but a complete system reset. You suspected that something goes wrong in db_disc_handler(), right? This function calls ble_nus_c_on_db_disc_evt() and that is a function written specifically for the NUS service. The original function has the following if-statement inside it:

if (p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE &&
    p_evt->params.discovered_db.srv_uuid.uuid == BLE_UUID_NUS_SERVICE &&
    p_evt->params.discovered_db.srv_uuid.type == p_ble_nus_c->uuid_type)
    {
        ....

If the original code is used with your beacon this if-statement will always be false because the beacon does not contain the BLE_UUID_NUS_SERVICE. This will "jump over" the code causing your problems. The code will continue to run, but not work as intended. Note that the if-statement will also be false if you change BLE_UUID_NUS_SERVICE to a random value, like 2, as you describe in your comment.

So I believe the problem is that you have changed the if statement to:

if (p_evt->evt_type == BLE_DB_DISCOVERY_COMPLETE &&
    p_evt->params.discovered_db.srv_uuid.uuid == BLE_UUID_OUR_SERVICE &&
    p_evt->params.discovered_db.srv_uuid.type == p_ble_nus_c->uuid_type)
    {
        ....

where BLE_UUID_OUR_SERVICE is a service UUID found on the beacon. However, you have forgotten to change BLE_UUID_NUS_RX_CHARACTERISTIC to BLE_UUID_OUR_CHARACTERISTC_UUID. Because you forgot that the CCCD handle is never updated. This causes ble_nus_c_rx_notif_enable() in ble_nus_c_evt_handler() to fail and return an error code. If you have not followed my advice in the comments about looking for asserts the result is that your code will reset over and over again and never work. If you did follow my advice you should have seen that the code asserts after ble_nus_c_rx_notif_enable(). Inside the function you will find the reason:

if ( (p_ble_nus_c->conn_handle == BLE_CONN_HANDLE_INVALID)
   ||(p_ble_nus_c->handles.nus_rx_cccd_handle == BLE_GATT_HANDLE_INVALID)
   )
    {
        return NRF_ERROR_INVALID_STATE;
    }

If you don't update the CCCD value this if-statement will return true and NRF_ERROR_INVALID_STATE is returned.

If I use your files and just change BLE_UUID_NUS_RX_CHARACTERISTIC to BLE_UUID_OUR_CHARACTERISTC_UUID the code seems to work fine and I get periodic notifications and "Eureka"s.

RE: Problems with the db discovery module

Revo — Wed, 11 May 2016 12:12:04 GMT

Ops sorry, i forgot that those libraries are in another directory! I attach the two libraries that were in someway modified, ble_nus.c and ble_db_discovery.c. Thanks again and sorry for not uploading it before! Note that some alterations in ble_nus.c are the one that you proposed in the other topic to fix is_uuid_present (marked with //NORDIC as you probably know ^^)!

RE: Problems with the db discovery module

MartinBL — Wed, 11 May 2016 12:05:56 GMT

Can you please upload your ble_nus_c.c file? This file is located in "your_SDK_folder\components\ble\ble_services\ble_nus_c" and hence is not included in your zip file. If you have altered it I believe we might find the cause to your troubles in there.

RE: Problems with the db discovery module

Revo — Wed, 11 May 2016 08:45:54 GMT

I uploaded the updated project file, but as you can see the only difference with the older version are the printf's that i used to track down the operations order; i also added a case in on_ble_evt for BLE_GAP_EVT_DISCONNECTED because as you can see in the older version this case wasn't event present. However, even when disconnecting, it doesn't enter in this case, i think because that case is not triggered in any part of the code.

I am using softdevice s130 and SDK 11 on the nrf51 DK, and softdevice s110 and SDK 7.1 in the smart beacon kit.

However i can't really understand how it can work on your devices and not on mine, it could really be something about compilation ^^'

RE: Problems with the db discovery module

MartinBL — Wed, 11 May 2016 08:25:19 GMT

Could you post your updated project files?
Can you look for BLE_GAP_EVT_DISCONNECTED events in on_ble_evt() and look for possible disconnect reasons in p_ble_evt->gap_evt.disconnected?
What exact Softdevice and SDK versions are you using?

RE: Problems with the db discovery module

Revo — Wed, 11 May 2016 07:42:06 GMT

Is there any news? Please Martin if the code works fine on your boards, can you upload the hex file for the nrf51 DK so i can verify that there are not compilation problems?

RE: Problems with the db discovery module

Revo — Mon, 09 May 2016 14:20:47 GMT

The other topics are from another user, but it's ok because in the topic you posted first i found almost the same informations and followed them letter by letter! However here is what i have done: i debugged the code that i posted using some printf (which means that i am in connection via UART, because i see the text in the printf's on TERMITE). As soon as the two devices connect (i know it because the LED indicating connection turns on, and the function is_uuid_present returns success) the following functions are called inside Ble_db_discovery.c (with relative cases if present), in order:

ble_db_discovery_start
ble_db_discovery_on_ble_evt -> case 	BLE_GATTC_EVT_PRIM_SRVC_DISC_RSP
on_primary_srv_discovery_rsp
characteristics_discover
ble_db_discovery_on_ble_evt -> case BLE_GATTC_EVT_CHAR_DISC_RSP
on_characteristic_discovery_rsp
is_char_discovery_reqd
characteristics_discover
ble_db_discovery_on_ble_evt -> case BLE_GATTC_EVT_CHAR_DISC_RSP
on_characteristic_discovery_rsp
descriptors_discover
is_desc_discovery_reqd
descriptors_discover

At the end of the last function, they just disconnect (and reconnect immediately after, executing the same functions again) instead of entering in db_disc_handler (i put here a printf too), and i can't really understand why.

P.S i also noticed a strange thing that maybe can help you understand. In the function db_disc_handler, there is a check on the UUID (in the if statemente immediately after the function definition); as you can see in my code, i put there BLE_UUID_OUR_SERVICE or whatever it is. I tried to change it with a random value, like "2", and the strange fact is that in this case all the functions listed before are executed, but the two devices don't disconnect at the last one and db_disc_handler is called! Of course it stops at the if statement because it doesn't find an UUID like "2", but the strange fact is that just changing this check value, they don't disconnect and it enters the function.

RE: Problems with the db discovery module

MartinBL — Mon, 09 May 2016 13:16:17 GMT

Can you debug your code and put a breakpoint in db_disc_handler to make sure that it is in fact never called?

RE: Problems with the db discovery module

MartinBL — Mon, 09 May 2016 13:15:57 GMT

Hi. I assume this is the recent topic you talk about? I tried your code and it seemed to work fine out of the box. Your central connected with the beacon, db_disc_handler was called, and the service with UUID 0xF00D was discovered.

Have you tried to define DEBUG in the Target Options -> C/C++ defines? As described here.

Are you sure that you are in a connection? If you define DEBUG as mentioned above the application will print out some nice messages on the UART terminal about what is going on.

And btw, this also seems to be you?

RE: Problems with the db discovery module

Revo — Mon, 09 May 2016 07:33:35 GMT

Please really nobody knows how to get the db discovery module working?