<error> ble_gatt: sd_ble_gap_data_length_update() (request) on connection 0x0 returned unexpected value 0x13.

[erltot]

Working on migrating my application from sdk 12.2 to sdk 14 except for some flash issues most of it seems to be working as before, except I notice this message in jlink:

 0> <info> app: Connected
 0> <error> ble_gatt: sd_ble_gap_data_length_update() (request) on connection 0x0 returned unexpected value 0x13.
 0> <info> app: Data len is set to 0x3D(61)

what does this mean?

Edit: using the BLE NUS peripheral example

It seems it comes from this function in #75 nrf_ble_gatt.c:

/**@brief   Start a data length update request.
 * @details This function is called to request a data length update upon connection.
 *          When the peer requests a data length update, sd_ble_gap_data_length_update()
 *          is called directly in response to the BLE_GAP_EVT_DATA_LENGTH_UPDATE event in
 *          on_data_length_update_evt().
 */
static void data_length_update(uint16_t conn_handle, nrf_ble_gatt_t const * p_gatt)
{
    NRF_LOG_DEBUG("Requesting to update data length to %u on connection 0x%x.",
                  p_gatt->links[conn_handle].data_length_desired, conn_handle);

    ble_gap_data_length_params_t const dlp =
    {
        .max_rx_octets  = p_gatt->links[conn_handle].data_length_desired,
        .max_tx_octets  = p_gatt->links[conn_handle].data_length_desired,
        .max_rx_time_us = BLE_GAP_DATA_LENGTH_AUTO,
        .max_tx_time_us = BLE_GAP_DATA_LENGTH_AUTO,
    };

    ret_code_t err_code = sd_ble_gap_data_length_update(conn_handle, &dlp, NULL);
    if (err_code != NRF_SUCCESS)
    {
        NRF_LOG_ERROR("sd_ble_gap_data_length_update() (request)"
                      " on connection 0x%x returned unexpected value 0x%x.",
                      conn_handle, err_code);
    }
}

[pbn4]

I also met this error, any solutions?

[erltot]

Nothing yet

[Petter Myhre]

0x13 is NRF_ERROR_RESOURCES - The requested parameters can not be accommodated. Inspect p_dl_limitation so see where the limitation is.

What parameters did you request? What are the values in p_dl_limitation? What is the max ATT MTU you have set? What kind of event length have you set?

[erltot]

Where do I inspect p_dl_limitation? I'm not sure I understand what you mean.

I have not changed these settings from the ble nus example, so should be fairly simple to reproduce.

[Petter Myhre]

p_dl_limitation is an argument to sd_ble_gap_data_length_update(). It might give a pointer to why you get the error, if the event length is too short, if the max ATT MTU is too small.