Please refer to the API and structure. You can use the parameter rfcomm_mtu.
/**
* Following structure is used to register application with wiced_bt_spp library
*/
typedef struct
{
uint8_t rfcomm_scn; /**< Application selects RFCOMM SCN that
it publishes in the SDP and need to
pass the same value for library to use. */
uint16_t rfcomm_mtu; /**< MTU to be be used by the RFCOMM layer */
wiced_bt_spp_connection_up_callback_t p_connection_up_callback; /**< iAP2 connection established */
wiced_bt_spp_connection_failed_callback_t p_connection_failed_callback; /**< iAP2 connection establishment failed */
wiced_bt_spp_service_not_found_callback_t p_service_not_found_callback; /**< iAP2 service not found */
wiced_bt_spp_connection_down_callback_t p_connection_down_callback; /**< iAP2 connection disconnected */
wiced_bt_spp_rx_data_callback_t p_rx_data_callback; /**< Data packet received */
} wiced_bt_spp_reg_t;
/**
* Function wiced_bt_spp_startup
*
* Initialize SPP library and starts the RFCOMM service.
*
* @param[in] p_reg : Registration control block that includes RFCOMM SCN and callbacks
* @return wiced_result_t : Result of operation
*/
wiced_result_t wiced_bt_spp_startup(wiced_bt_spp_reg_t *p_reg);
