Characteristic cannot show descriptors

[kenyon]

Hi 
I tried to put descriptor on the characteristic recently and it didn't seem to work. Is there something wrong with that?

/*Initialize alert service parameter and add charactoristics to the service*/
uint32_t ble_alert_init(ble_nus_t * p_alert, ble_nus_init_t const * p_alert_init)
{
    uint32_t      err_code;
    ble_uuid_t    ble_uuid;
    ble_uuid128_t alert_base_uuid = ALERT_BASE_UUID;

    VERIFY_PARAM_NOT_NULL(p_alert);
    VERIFY_PARAM_NOT_NULL(p_alert_init);

    /*Initialize the second custom service structure.*/
    p_alert->data_handler            = p_alert_init->data_handler;

    err_code = sd_ble_uuid_vs_add(&alert_base_uuid, &p_alert->uuid_type);
    //VERIFY_SUCCESS(err_code);

    ble_uuid.type = p_alert->uuid_type;
    ble_uuid.uuid = BLE_UUID_ALERT_SERVICE;

    /*Add second custom service.*/
    err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
                                        &ble_uuid,
                                        &p_alert->service_handle);
    VERIFY_SUCCESS(err_code);
    /**@snippet [Adding proprietary characteristic to the SoftDevice] */

    ble_add_char_params_t add_char_params;
    ble_add_char_user_desc_t user_desc_config_struct;
    ble_add_char_user_desc_t user_desc_alert_struct;
    
    // Initialize and add the Configuration Characteristic
    memset(&add_char_params, 0, sizeof(add_char_params));
    add_char_params.uuid                     = BLE_UUID_NUS_CONFIG_CHARACTERISTIC;
    add_char_params.uuid_type                = p_alert->uuid_type;
    add_char_params.max_len                  = sizeof(uint8_t);
    add_char_params.init_len                 = sizeof(uint8_t);
    add_char_params.is_var_len               = false;
    add_char_params.p_init_value             = &Threshold;
    add_char_params.char_props.read          = 1;
    add_char_params.char_props.write_wo_resp = 1;

    add_char_params.read_access              = SEC_OPEN;
    add_char_params.write_access             = SEC_OPEN;

    static char user_desc_config[] = "CONFIGURATION";
    user_desc_config_struct.p_char_user_desc = (uint8_t*)user_desc_config;
    user_desc_config_struct.max_size = strlen(user_desc_config);
    user_desc_config_struct.size = strlen(user_desc_config);
    user_desc_config_struct.is_var_len       = false;
    
    add_char_params.p_user_descr = &user_desc_config_struct;
    
    err_code = characteristic_add(p_alert->service_handle, &add_char_params, &p_alert->tx_handles);

    if (err_code != NRF_SUCCESS)
    {
        return err_code;
    }

    // Initialize and add the Alert Characteristic
    uint8_t sampledata[] = "HELLO_LUMOS";
    memset(&add_char_params, 0, sizeof(add_char_params));
    add_char_params.uuid                     = BLE_UUID_NUS_ALERT_CHARACTERISTIC;
    add_char_params.uuid_type                = p_alert->uuid_type;
    add_char_params.max_len                  = sizeof(sampledata);
    add_char_params.init_len                 = strlen((char*)sampledata);
    add_char_params.is_var_len               = true;
    add_char_params.p_init_value             = sampledata;
    add_char_params.char_props.notify        = 1;
    add_char_params.char_props.write_wo_resp = 1;

    add_char_params.read_access              = SEC_OPEN;
    add_char_params.write_access             = SEC_OPEN;
    add_char_params.cccd_write_access        = SEC_OPEN;

    static char user_desc_alert[] = "ALERTS";
    user_desc_alert_struct.p_char_user_desc = (uint8_t*)user_desc_alert;
    user_desc_alert_struct.max_size         = strlen(user_desc_alert);
    user_desc_alert_struct.size             = strlen(user_desc_alert);

    add_char_params.p_user_descr = &user_desc_alert_struct;    
    err_code = characteristic_add(p_alert->service_handle, &add_char_params, &p_alert->rx_handles);
    
    return err_code;

}

If I take the following code that adds characteristic, descriptor will be displayed successfully,I want to know why my code above won't display descriptor.

/*Initialize alert service parameter and add charactoristics to the service*/
uint32_t ble_alert_init(ble_nus_t * p_alert, ble_nus_init_t const * p_alert_init)
{
    uint32_t      err_code;
    ble_uuid_t    ble_uuid;
    uint8_t value[130]  = {0x00};
    uint8_t       data_len = 0;
    ble_uuid128_t alert_base_uuid = ALERT_BASE_UUID;

    VERIFY_PARAM_NOT_NULL(p_alert);
    VERIFY_PARAM_NOT_NULL(p_alert_init);

    /*Initialize the second custom service structure.*/
    p_alert->data_handler            = p_alert_init->data_handler;

    err_code = sd_ble_uuid_vs_add(&alert_base_uuid, &p_alert->uuid_type);
    //VERIFY_SUCCESS(err_code);

    ble_uuid.type = p_alert->uuid_type;
    ble_uuid.uuid = BLE_UUID_ALERT_SERVICE;

    /*Add second custom service.*/
    err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY,
                                        &ble_uuid,
                                        &p_alert->service_handle);
    VERIFY_SUCCESS(err_code);
    /**@snippet [Adding proprietary characteristic to the SoftDevice] */

    ble_gatts_char_md_t char_md;
    ble_gatts_attr_md_t cccd_md;
    ble_gatts_attr_t    attr_char_value;
    ble_gatts_attr_md_t attr_md;

    memset(&cccd_md, 0, sizeof(cccd_md));

    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.write_perm);
    cccd_md.vloc = BLE_GATTS_VLOC_STACK;
    
    static char *text1 = "CONFIGUARTION";
    memset(&char_md, 0, sizeof(char_md));
    char_md.char_props.read = 1;
    char_md.char_props.write_wo_resp = 1;
    char_md.p_char_user_desc = (uint8_t*) text1;
    char_md.char_user_desc_size = strlen(text1);
    char_md.char_user_desc_max_size = strlen(text1);
    char_md.p_char_pf = NULL;
    char_md.p_user_desc_md = NULL;
    char_md.p_cccd_md = &cccd_md;
    char_md.p_sccd_md = NULL;

    memset(&attr_md, 0, sizeof(attr_md));
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.write_perm);
    attr_md.vloc    = BLE_GATTS_VLOC_STACK;
    attr_md.rd_auth = 0;
    attr_md.wr_auth = 0;
    attr_md.vlen    = 1;

    memset(&attr_char_value, 0, sizeof(attr_char_value));
    /*  Add config char */
    ble_uuid.type = p_alert->uuid_type;
    ble_uuid.uuid = BLE_UUID_NUS_CONFIG_CHARACTERISTIC;

    data_len = 1;
    
    /*Get Device configuration Length.*/
    attr_char_value.p_uuid    = &ble_uuid;
    attr_char_value.p_attr_md = &attr_md;
    
    attr_char_value.init_len  = data_len;
    attr_char_value.init_offs = 0;
    attr_char_value.max_len   = data_len;

    attr_char_value.p_value = &Threshold;
    //printf("\nThreshold %d\n",Threshold);

    sd_ble_gatts_characteristic_add(p_alert->service_handle,
                                           &char_md,
                                           &attr_char_value,
                                           &p_alert->tx_handles);
    
    // Initialize and add the Configuration Characteristic
    static char *text2 = "ALERTS";
    memset(&char_md, 0, sizeof(char_md));
    char_md.char_props.notify = 1;
    char_md.char_props.write_wo_resp  = 1;
    char_md.p_char_user_desc  = (uint8_t *)text2; //NULL;
    char_md.char_user_desc_size = strlen(text2);
    char_md.char_user_desc_max_size = strlen(text2);
    ble_uuid.uuid = BLE_UUID_NUS_ALERT_CHARACTERISTIC;

    memset(&cccd_md, 0, sizeof(cccd_md));    
    
    cccd_md.vloc = BLE_GATTS_VLOC_STACK;
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.read_perm);
    BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.write_perm);

    attr_md.vloc    = BLE_GATTS_VLOC_STACK;
    attr_md.rd_auth = 1;
    attr_md.wr_auth = 0;
    attr_md.vlen    = 1;
    
    memset(&attr_char_value, 0, sizeof(attr_char_value));
    memset(value, 0x00, sizeof(value));
    char *sampledata = "HELLO_LUMOS";

    data_len = strlen(sampledata);

    attr_char_value.p_uuid    = &ble_uuid;
    attr_char_value.p_attr_md = &attr_md;

    attr_char_value.init_len  = data_len;
    attr_char_value.init_offs = 0;
    attr_char_value.max_len   = strlen(sampledata);

    attr_char_value.p_value = (uint8_t*)sampledata;

    return sd_ble_gatts_characteristic_add(p_alert->service_handle,
                                           &char_md,
                                           &attr_char_value,
                                           &p_alert->rx_handles);
}

Best regard

[Einar Thorsrud]

Hi,

The names you give to characteristics only exist locally in your implementation (or in a standard document if it is a standard sevice). Over the air, only numbers are usedin Bluetooth, so you will need to map the UUID value to what it represents (and name it) in all implementations, for in your mobile phone app. nRF Connect for mobile cannot know what you want to name your servies, and will only show the UUID (it shows names for some services/characteristics that is knows about because it is part of the app implementation).