BLE adding characteristic doesn´t work

Question

Hi, 
 
 I´m trying to add a new, custom TX characteristic to Softdevice. I use example from SDK 16 "UART/Serial Port Emulation over BLE". 
 
 How I can do this, is explained here: " https://infocenter.nordicsemi.com/index.jsp?topic=%2Fsdk_nrf5_v16.0.0%2Fble_sdk_app_nus_eval.html&cp=7_1_4_2_2_25_0_0&anchor=adding_prop_ser_and_char" 
 
 So I add the following code to "ble_nus.c": 
 #define test 0x0005 /**< The UUID of the test Characteristic. */
memset(&add_char_params, 0, sizeof(add_char_params));
add_char_params.uuid = test;
add_char_params.uuid_type = p_nus->uuid_type;
add_char_params.max_len = BLE_NUS_MAX_TX_CHAR_LEN;
add_char_params.init_len = sizeof(uint8_t);
add_char_params.is_var_len = true;
add_char_params.char_props.notify = 1;

add_char_params.read_access = SEC_OPEN;
add_char_params.write_access = SEC_OPEN;
add_char_params.cccd_write_access = SEC_OPEN;

return characteristic_add(p_nus->service_handle, &add_char_params, &p_nus->tx_handles); 
 
 But there is no new TX characteristic in nRF connect App. The both other standard characteristics are addet in similar way. 
 
 What I´m doing wrong?

Edvin · Accepted Answer

Hello Simon. 
 
 So you say that all the data that you send is sent via the last characteristic? 
 If you look at the implementation of ble_nus_data_send(), you will see that it uses a handle called: 
 hvx_params.handle = p_nus->tx_handles.value_handle; 
 So if this handle is used in the implementation of the characteristic, I guess it would always be the last one. 
 You should add a new handle to all the new characteristics that you add. Look at how the tx_handle is added, compared to the rx_handle in the unmodified example. 
 Try adding some new handles in: 
 struct ble_nus_s
{
 uint8_t uuid_type; /**< UUID type for Nordic UART Service Base UUID. */
 uint16_t service_handle; /**< Handle of Nordic UART Service (as provided by the SoftDevice). */
 ble_gatts_char_handles_t tx_handles; /**< Handles related to the TX characteristic (as provided by the SoftDevice). */
 ble_gatts_char_handles_t rx_handles; /**< Handles related to the RX characteristic (as provided by the SoftDevice). */
 blcm_link_ctx_storage_t * const p_link_ctx_storage; /**< Pointer to link context storage with handles of all current connections and its context. */
 ble_nus_data_handler_t data_handler; /**< Event handler to be called for handling received data. */
}; 
 in ble_nus.h, and use these handles instead of the tx_handle when you add the new characteristics. 
 Then you need to add something in ble_nus_data_send() that can take one extra parameter, which says what characteristic handle that you want to use to send the data.

BLE adding characteristic doesn´t work

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