Problem when establish a connection: p_gap_evt->conn_handle = 292

[BMG]

Hello,

I'm using 2 sparkfun nrf52840 boards. On the central board I'm using ble_app_multilink_central (trying to integrate ble_app_uart_c example) and on the peripheral: ble_app_uart.

When connected, in ble_evt_handler, at BLE_GAP_EVT_CONNECTED, I get a reset because of the function:

APP_ERROR_CHECK_BOOL(p_gap_evt->conn_handle < NRF_SDH_BLE_CENTRAL_LINK_COUNT);

where p_gap_evt->conn_handle is 292.

Can you tell me, please, what does this value mean?

I guess that this is the cause why I cannot send any string from central to peripheral through ble_nus_c_string_send or ble_nus_data_send.

I'm using nRF5_SDK_15.3.0_59ac345,  s140.

Thank you.

[Amanda Hsieh]

Hi, 

p_gap_evt->conn_handle is Connection Handle on which event occurred.

Since p_gap_evt->conn_handle is 292 which is larger than NRF_SDH_BLE_CENTRAL_LINK_COUNT (defined in sdk_config.h.), it might cause the reset. 

-Amanda H.

[BMG]

I understand, but why this happens?

How can I solve this?

[Amanda Hsieh]

Hi, 

What is the error code you got from sd_ble_gatts_value_get()? That is an SD function which could not be accessed by users. 

-Amanda H.

[BMG]

Hi Amanda,

I don't have a debugger, so I don't know which is the error code returned, but if you tell me which are the possible error codes returned by this function, I will check. 

Thank you.

[Amanda Hsieh]

Hi, 

sd_ble_gatts_value_get() might return values:

NRF_SUCCESS	Successfully retrieved the value of the attribute.
NRF_ERROR_INVALID_ADDR	Invalid pointer supplied.
NRF_ERROR_NOT_FOUND	Attribute not found.
NRF_ERROR_INVALID_PARAM	Invalid attribute offset supplied.
BLE_ERROR_INVALID_CONN_HANDLE	Invalid connection handle supplied on a system attribute.
BLE_ERROR_GATTS_SYS_ATTR_MISSING	System attributes missing, use sd_ble_gatts_sys_attr_set to set them to a known value.

I don't know which error code you got. I would suggest Installing SEGGER tools to debug and compile with the debug mode. The log could indicate more detail for you. This video could guide you to debug. 

-Amanda H.

[BMG]

Thank you! I installed Segger Embedded Sutdio, but I don't have a J-Link emulator, so I can't debug the code.

Can I debug & run the code without the emulator, only through USB?

The error I get is NRF_ERROR_NOT_FOUND.

[Amanda Hsieh]

Hi, 

BMG said:

Can I debug & run the code without the emulator, only through USB?

There is no debugger on that board. There is a debug interface (SWD) that you can connect a debugger to for programming the board, but you still need an external debugger for programming. This is also shown in the SWD Interface section of the SparkFun Pro nRF52840 Mini Hookup Guide.

BMG said:

The error I get is NRF_ERROR_NOT_FOUND.

That error means Attribute not found. The sd_ble_gatts_value_get() that is used in the on_connect() function. In that case, the attribute is the CCCD(Client Characteristic Configuration Descriptor). Please see this post.  

-Amanda H.  

[BMG]

\thank you for the information, but how can I solve this? Because on ble_app_uart (peripheral), I do not have this type of problem

[Amanda Hsieh]

Hi,

BMG said:

Because on ble_app_uart (peripheral), I do not have this type of problem

Could you elaborate more? 

Do you mean your ble_app_multilink_central (trying to integrate ble_app_uart_c example) and on the peripheral: ble_app_uart can work? 

Please also check the connection handle in handles_assign of ble_app_uart_c and ble_app_multilink_c. 

-Amanda H.