Re: Sending notification with MTU size more than 23 bytes - BLE


Johan Hedberg
 

Hi DJ,

On Fri, Dec 15, 2017, dhananjay gj wrote:
I have a question regarding handling MTU size more than 23 bytes
during notification. I have a custom service on a peripheral device app to
which client app(lets say android app) will subscribe to. When the
peripheral device has some data ( usually more than 23 bytes) it will send
the data to the client via 'notification'. I saw many solutions with
respect to nRF SDK but i am not using any SDK but just developing the
peripheral device app using zephyr's BLE APIs. I would like to know how to
handle this?

I came across MTU negotiation during connection while searching on this. I
couldn't find any sample code on zephyr using this method. Does peripheral
device app has to do anything during this negotiation?
The maxium ATT MTU Zephyr will use is based on the values you've given
to CONFIG_BT_L2CAP_TX_MTU and CONFIG_BT_L2CAP_RX_MTU. Additionally,
there's a runtime API bt_gatt_exchange_mtu() that can be used to trigger
the MTU negotiation if it doesn't otherwise happen.

Johan

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