bt_gatt_client_mtu_get()

Function requests and gets maximum transfer unit of described connection.

Syntax

Description

bt_gatt_client_mtu_get(connection_id, mtu_len);

Parameters

Variable	Input

Variable	Input
`connection_id`	Connection id which was described in `bt_gatt_client_connect` function. Could be either 0 or 1.
`mtu_len`	A variable onto which mtu will be written.

Returns

Return value	Return explanation
SCRIPT_OPERATION_SUCCESS	Successfully fetched mtu.
SCRIPT_OPERATION_FAILED	Failed to fetch mtu.
SCRIPT_NO_ACCESS	Bluetooth GATT client is not initialized.

Function call example

#include <io>
#include <read>
#include <float>
#include <string>
#include <core>
#include <write>
#include <define>
#include <socket>
#include <bluetooth>

#define FIRST_CONNECTION       0
#define SECOND_CONNECTION      1

new peer_mac_address[] = [0xFF, 0x48, 0x80, 0x33, 0xE3, 0xA8];
new mtu_len = 0;

main()
{   
    bt_init();
    bt_gatt_client_init();
    while (bt_gatt_client_connect(FIRST_CONNECTION, BT_ADDR_RANDOM, peer_mac_address) != SCRIPT_OPERATION_SUCCESS)
    {
        Delay(100);
    }
    bt_gatt_client_mtu_get(FIRST_CONNECTION, mtu_len);
    for(;;)
    {
        Delay(100);
    }
}

Debug example

This example initializes BLE, then initializes GATT Client module, connects to peer device and gets maximum transfer unit of the connection. Example uses debug_print function to print information log to Initialized peripheral.

#include <io>
#include <read>
#include <float>
#include <string>
#include <core>
#include <write>
#include <define>
#include <socket>
#include <bluetooth>
#include <debug>

#define RS232_SPEED         115200
#define WORD_LENGTH         WORDLENGTH_8
#define STOP_BITS           STOPBITS_1
#define PARITY              PARITY_NONE

#define FIRST_CONNECTION       0
#define SECOND_CONNECTION      1

new peer_mac_address[] = [0xFF, 0x48, 0x80, 0x33, 0xE3, 0xA8];
new return_code = SCRIPT_OPERATION_SUCCESS;
new mtu_len = 0;

main()
{
    Init(RS232, RS232_SPEED, WORD_LENGTH, STOP_BITS, PARITY);
    debug_init(RS232);
    
    return_code = bt_init();
    if (return_code != SCRIPT_OPERATION_SUCCESS)
    {
        // Handle failed bt_init here
        debug_print("bt_init failed\r\n");
    }
    else 
    {
        debug_print("bt_init succeeded\r\n");
    }
    
    return_code = bt_gatt_client_init();
    if (return_code != SCRIPT_OPERATION_SUCCESS)
    {
        // Handle failed bt_gatt_client_init here
        debug_print("bt_gatt_client_init failed\r\n");
    }
    else 
    {
        debug_print("bt_gatt_client_init succeeded\r\n");
    }
    debug_print("Connecting to a device with this MAC address: %X:%X:%X:%X:%X:%X\r\n", peer_mac_address[0], 
                peer_mac_address[1], peer_mac_address[2], peer_mac_address[3], peer_mac_address[4], peer_mac_address[5]);
    while (bt_gatt_client_connect(FIRST_CONNECTION, BT_ADDR_RANDOM, peer_mac_address) != SCRIPT_OPERATION_SUCCESS)
    {
        debug_print("bt_gatt_client_connect time-out\r\n");
        Delay(100);
    }
    debug_print("Connected successfully\r\n");
    return_code = bt_gatt_client_mtu_get(FIRST_CONNECTION, mtu_len);
    if (return_code != SCRIPT_OPERATION_SUCCESS)
    {
        // Handle failed bt_gatt_client_mtu_get here
        debug_print("bt_gatt_client_mtu_get failed\r\n");
    }
    else 
    {
        debug_print("bt_gatt_client_mtu_get succeeded\r\n");
        debug_print("MTU: %i\r\n", mtu_len);
    }
    
    for(;;)
    {   
        Delay(1000);
    }
}

Notes and Warnings

If this function is never called then default MTU will be 23 bytes. Otherwise it will be a value which is returned into passed variable.