not able to send more the 20 bytes using bt_gatt_notify api

[madhurubharath]

i am using SDK 1.9.1 to notify data  to peripheral to central device i am using ''bt_gatt_notify " api to send data to mobile but i am able to send only 20 bytes data to central device ,but my requirement i am getting packets from MCU  with 240 bytes each pkt ,but i am not able to transmit full pkt once data i am splitting the pkt 20 bytes  and sending but the requirement is need to send pkt by pkt continually please help to solve the problem.   

[madhurubharath]

please suggest any other method  to transmit data.

[madhurubharath]

APP FILE:

uint8_t TM_u8SendData_central_dev(tm_u8_t *BT_rx_data,uint16_t rxbuflen)

{

   int tm_status=0,Ack_len,nty_count=0,ble_tx_size=0;

   ble_buff_len=rxbuflen;

   uart_irq_rx_enable(uartDev);

   char AckMent[11];

   char buff_size[20];

   if(tm_flag == 1)

   {

    size_t size=0, SendLen=0;

    char *sPtr= BT_rx_data;

    tm_status=bt_gatt_notify(NULL, &ccbg_serv.attrs[1], sPtr ,ble_buff_len);

    if(tm_status == 0)

    {

      Ack_len = sprintf(AckMent,"{\"ack\":[0]}");

      UARTQueueData(&AppInstance.UartQTx, uartDev,AckMent,Ack_len);

      sprintf(buff_size,"pkt_data_size:%d",ble_buff_len);

      UARTQueueData(&AppInstance.UartQTx, uartDev,buff_size,sizeof(buff_size));

      return 0;

    }

    else

    {

      Ack_len = sprintf(AckMent,"{\"ack\":[-1]}");

      UARTQueueData(&AppInstance.UartQTx, uartDev,AckMent,Ack_len);

      sprintf(buff_size,"pkt_data_size:%d",ble_buff_len);

      UARTQueueData(&AppInstance.UartQTx, uartDev,buff_size,sizeof(buff_size));    

      return -1;

    }

}

prj.config:

 

CONFIG_BT_BUF_ACL_RX_SIZE=251

CONFIG_BT_L2CAP_TX_MTU=247

CONFIG_BT_BUF_ACL_TX_SIZE=251

CONFIG_BT_CTLR_DATA_LENGTH_MAX=251

this is my configuration code:

if i transmitt more then 20 bytes its returning -1

please help me to solve this issue

regards,

bharath.m

[Edvin]

Did you call bt_gatt_exchange_mtu(), like it is done in the throughput example found in ncs\nrf\samples\bluetooth\throughput?

And also, I see that you are using bt_gatt_notify(NULL, &ccbg_serv.attrs[1], sPtr ,ble_buff_len); that is, without the connection handle. Can you please try to use the connection handle instead of NULL when you are trying to send the data? I suspect that when you don't specify a specific connection, you can't use an MTU larger than the default MTU size. At least it is a quick check whether it works changing that.

Best regards,

Edvin

[madhurubharath]

hello edvin if i use  bt_gatt_exchange function  i ma not able to connect the device to central device its i think it resting the controller i dont know exactly. 

err = bt_gatt_exchange_mtu(default_conn,&exchange_params);
if(err == 0)
{
DPRINTF("MTU CHANGED\n\r");
}
else
{
DPRINTF("MTU NOT_CHANGED\n\r");
}

and now i am using default_con in the place of NULL

tm_status=bt_gatt_notify(default_conn, &ccbg_serv.attrs[1], sPtr ,ble_tx_size);

 

please help to solve this problem

regards,

bharath.m

[madhurubharath]

if i am trying to use   this function bt_gatt_exchange_mtu this function is not fetching controller stops  rest of the functions are not working.

it will be grate for my project if you solve this problem 

thanks &regards,

bharath.m.

[Edvin]

madhurubharath said:

if i use  bt_gatt_exchange function  i ma not able to connect the device to central device

What does it do? Does the log say anything? Does it print "MTU CHANGED" or "MTU NOT_CHANGED"?

madhurubharath said:

and now i am using default_con in the place of NULL

tm_status=bt_gatt_notify(default_conn, &ccbg_serv.attrs[1], sPtr ,ble_tx_size);

What does bt_gatt_notify return? What is tm_status after bt_gatt_notify has been called? (try printing it in the log).

[madhurubharath]

its disconnecting the BLE. from central device.

[Edvin]

Does the application crash/reset? Or does it trigger a bt_disconnect()? The bluetooth stack never disconnects on it's own. What does the log say?

BR,

Edvin

[madhurubharath]

After flashing the code application is crashing and not able to connect to peripheral. but if i remove this function (bt_gatt_exchange_mtu) its connecting .

its not printing any log because its crashing or resetting the BLE.

warm regards,

bharath.m