How to increase the length of characteristic value?

RE: How to increase the length of characteristic value?

Amanda Hsieh — Mon, 16 Sep 2019 11:52:27 GMT

Hi,

The last reply was two months ago and the latest problem seems far away from the original title/question.

Please create a new support case for it. Thanks.

-Amanda H.

RE: How to increase the length of characteristic value?

bscdb — Thu, 12 Sep 2019 22:53:04 GMT

I added all the stuff as mentioned in the link above but still there are disconnections. Reattaching my newly modified files.

devzone.nordicsemi.com/.../6064.ble_5F00_cus.c devzone.nordicsemi.com/.../ble_5F00_cus.h devzone.nordicsemi.com/.../707623.main.c

RE: How to increase the length of characteristic value?

Amanda Hsieh — Mon, 08 Jul 2019 07:47:00 GMT

Hi,

Yes, I tested with nRFconnect PC/mobile. It can read/write 29 bytes. If you enable the notification, it will disconnect immediately. You can refer to this https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-characteristics-a-beginners-tutorial to check the notification setting.

-Amanda H.

RE: How to increase the length of characteristic value?

bscdb — Fri, 05 Jul 2019 18:42:39 GMT

No Amanda, its still disconnecting. Did you check on nrfconnect? I'm also trying to send 0x01 & 0x02 values to output characteristics.

RE: How to increase the length of characteristic value?

Amanda Hsieh — Thu, 04 Jul 2019 12:59:25 GMT

Hi,

The attached file devzone.nordicsemi.com/.../230855_5F00_0537_5F00_ble_5F00_app_5F00_template.zip is modified as the last suggestion. It can work on my side.

-Amanda H.

RE: How to increase the length of characteristic value?

Amanda Hsieh — Thu, 04 Jul 2019 06:19:49 GMT

We are enduring heavy loading because many colleagues are on vacation.

I will back your case soon. Thank you for your understanding.

-Amanda

RE: How to increase the length of characteristic value?

bscdb — Wed, 03 Jul 2019 17:37:58 GMT

Did you find anything?

RE: How to increase the length of characteristic value?

bscdb — Tue, 02 Jul 2019 21:26:13 GMT

Hi Amanda, I'm still facing problems with all these changes. The bluetooth is getting disconnected. Please check my code. You can just search for /*NEW CHANGE*/ in my code to track the changes.

devzone.nordicsemi.com/.../5314.ble_5F00_app_5F00_template.zip

I could not trace the error.

Please help!!

RE: How to increase the length of characteristic value?

Amanda Hsieh — Wed, 19 Jun 2019 12:14:49 GMT

Hi,

Change the Line 46 as

    attr_char_value.init_len     = 29*sizeof(uint8_t);

-Amanda

RE: How to increase the length of characteristic value?

bscdb — Mon, 17 Jun 2019 15:12:51 GMT

/**@brief Function for adding the Data I/O characteristic. */
static uint32_t data_io_char_add(ble_midi_service_t * p_midi_service, const ble_midi_service_init_t * p_midi_service_init)
{
    uint32_t   err_code;
    ble_gatts_char_md_t char_md;
    ble_gatts_attr_md_t cccd_md;
    ble_gatts_attr_t    attr_char_value;
    ble_uuid_t          ble_uuid;
    ble_gatts_attr_md_t attr_md;
    // Configure the CCCD which is needed for Notifications and Indications
    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;
    // Configure the characteristic metadata.
    memset(&char_md, 0, sizeof(char_md));
    char_md.char_props.read          = 1;
    char_md.char_props.write_wo_resp = 1;
    char_md.char_props.notify        = 1;
    char_md.p_char_user_desc         = NULL;
    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;
    // Add the MIDI Data I/O Characteristic UUID
    ble_uuid128_t base_uuid = {BLE_UUID_MIDI_DATA_IO_CHAR_BASE_UUID};
    err_code = sd_ble_uuid_vs_add(&base_uuid, &p_midi_service->uuid_type);
    if (err_code != NRF_SUCCESS)
    {
        return err_code;
    }
    ble_uuid.type = p_midi_service->uuid_type;
    ble_uuid.uuid = BLE_UUID_MIDI_DATA_IO_CHAR_UUID;
    // Configure the characteristic value's metadata
    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       = 0;
    // Configure the characteristic value
    memset(&attr_char_value, 0, sizeof(attr_char_value));
    attr_char_value.p_uuid       = &ble_uuid;
    attr_char_value.p_attr_md    = &attr_md;
    attr_char_value.init_len     = sizeof(uint8_t);
    attr_char_value.init_offs    = 0;
    attr_char_value.max_len      = 29*sizeof(uint8_t);
    attr_char_value.p_value      = NULL;
    return sd_ble_gatts_characteristic_add(p_midi_service->service_handle, &char_md, &attr_char_value, &p_midi_service->data_io_char_handles);
}

I am also attaching the full code for your reference. Please have a look.

devzone.nordicsemi.com/.../0537.ble_5F00_app_5F00_template.zip

RE: How to increase the length of characteristic value?

Amanda Hsieh — Mon, 17 Jun 2019 13:24:35 GMT

Could you provide the code where you initializes the characteristic?

The code before sd_ble_gatts_characteristic_add ().

-Amanda

RE: How to increase the length of characteristic value?

bscdb — Sun, 16 Jun 2019 14:34:12 GMT

I'm using ble_app_template example in SDK 15.2.

I have set gatts_value.len = 29*sizeof(uint8_t);

uint32_t ble_midi_data_io_value_update(ble_midi_service_t * p_midi_service, uint8_t data_io_value[29])
{
    if (p_midi_service == NULL)
    {
        return NRF_ERROR_NULL;
    }
    uint32_t err_code = NRF_SUCCESS;
    ble_gatts_value_t gatts_value;
    // Initialize value struct.
    memset(&gatts_value, 0, sizeof(gatts_value));
    gatts_value.len     = 29*sizeof(uint8_t);
    gatts_value.offset  = 0;
    gatts_value.p_value = &data_io_value[0];
    // Update database.
    err_code = sd_ble_gatts_value_set(p_midi_service->conn_handle, p_midi_service->data_io_char_handles.value_handle, &gatts_value);
    if (err_code != NRF_SUCCESS)
    {
        return err_code;
    }
    // Send value if connected and notifying.
    if ((p_midi_service->conn_handle != BLE_CONN_HANDLE_INVALID)) 
    {
        ble_gatts_hvx_params_t hvx_params;
        memset(&hvx_params, 0, sizeof(hvx_params));
        hvx_params.handle = p_midi_service->data_io_char_handles.value_handle;
        hvx_params.type   = BLE_GATT_HVX_NOTIFICATION;
        hvx_params.offset = gatts_value.offset;
        hvx_params.p_len  = &gatts_value.len;
        hvx_params.p_data = gatts_value.p_value;
        err_code = sd_ble_gatts_hvx(p_midi_service->conn_handle, &hvx_params);
        NRF_LOG_INFO("sd_ble_gatts_hvx result: %x. \r\n", err_code); 
    }
    else
    {
        err_code = NRF_ERROR_INVALID_STATE;
        NRF_LOG_INFO("sd_ble_gatts_hvx result: NRF_ERROR_INVALID_STATE. \r\n"); 
    }
    return err_code;
}

Please guide what else do I need to add?

RE: How to increase the length of characteristic value?

Amanda Hsieh — Fri, 14 Jun 2019 08:27:20 GMT

Hi,

What SDK version and example do you use?

What is the value of &gatts_value.len?

Best regards,

Amanda