not able to send more the 20bytes in notification character using bt_gatt_notify api go through different tickets still not able to send more then 20bytes

[madhurubharath]

i am receiving some packets so i need to send that packet to central device(mobile) if i send 20-20bytes it successfully sending the data to central device(mobile) if its more then 20 bytes its returning -128 ,i have changed mtu size .

proji.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

main.c:

 err = bt_gatt_exchange_mtu(current_conn1,&exchange_params);

   if(err == 0)

   {

    DPRINTF("MTU CHANGED\n\r");

   }

   else

   {

    DPRINTF("MTU NOT_CHANGED\n\r");

   }

and using 

tm_status=bt_gatt_notify(current_conn1, &ccbg_serv.attrs[1], sPtr ,ble_tx_size); to notify

still it's not sending full pkt to ble central device(mobile vie ble)

[Simon]

I was able to send 30 bytes using this sample: https://github.com/simon-iversen/ncs_samples/tree/master/ble_peripheral_cus_service 

I connected it to the nRF Connect Mobile app, enabled notifications, and requested a larger MTU from the phone:

Best regards,

Simon

[madhurubharath]

TQ simon its working now after changing the length of MTU in nrf connect.

but one thing i am not understanding if we have own customized app how can set this MTU  size in that app.

instead of  this how can we set this in code.

[Simon]

madhurubharath said:

but one thing i am not understanding if we have own customized app how can set this MTU  size in that app.

It is hard to give you any hints on this, since I don't know what framework/programming language you're using (Javascript (React/Flutter) or developing directly for iOS and Android and using Java and Swift). 

However, this may be useful:  One minute to understand BLE MTU data package 

By the way, I can see that you have asked about the same (not able to send more than 20 bytes) in this thread  not able to send more the 20 bytes using bt_gatt_notify api, so please continue the discussion there. There is no point of having to open tickets about the same topic.

Best regards,

Simon 

[madhurubharath]

tq simon for your support,

now its working after changing the MTU size in nrf connect app. 

warm regards,

bharath.m