DLE (data length extension) and max att_mtu function to application

RE: DLE (data length extension) and max att_mtu function to application

CFF.K — Tue, 11 Jun 2019 01:10:00 GMT

Hi Kenneth:

Could you help me something to figure out these questions?

RE: DLE (data length extension) and max att_mtu function to application

CFF.K — Thu, 06 Jun 2019 06:24:04 GMT

Hi Kenneth:

sorry, I really don't know which do you answer. I know you support code, but I don't know what relates with my question.

Maybe I'm not smart, If my question isn't clear, please tell me. Could you mark the number of the question when you answer?

RE: DLE (data length extension) and max att_mtu function to application

Kenneth — Wed, 05 Jun 2019 11:42:04 GMT

Hi,

Many of the examples you can find in the nRF5 SDK have the following line of code:

    err_code = nrf_ble_gatt_init(&m_gatt, gatt_evt_handler);
    APP_ERROR_CHECK(err_code);

You can then get information about the supported lengths in the callback handler:

/** @brief Function for handling events from the GATT library. */
void gatt_evt_handler(nrf_ble_gatt_t * p_gatt, nrf_ble_gatt_evt_t const * p_evt)
{
    if ((m_conn_handle == p_evt->conn_handle) && (p_evt->evt_id == NRF_BLE_GATT_EVT_ATT_MTU_UPDATED))
    {
        m_ble_nus_max_data_len = p_evt->params.att_mtu_effective - OPCODE_LENGTH - HANDLE_LENGTH;
        NRF_LOG_INFO("Data len is set to 0x%X(%d)", m_ble_nus_max_data_len, m_ble_nus_max_data_len);
    }
    NRF_LOG_DEBUG("ATT MTU exchange completed. central 0x%x peripheral 0x%x",
                  p_gatt->att_mtu_desired_central,
                  p_gatt->att_mtu_desired_periph);
}

Kenneth