nRF52832 setting issue

[Francis Feng]

Could you please check it? According to the packet capture, MTU is set to 247 in the front, but 27 actually seems to be used for subsequent transmission, right?

The first time I use wireshark to catch a Bluetooth packet, I am not sure. The following picture seems to show that the device sends 27 bytes and the phone responds with ack, and then the device sends 27 bytes and the phone responds with ack, right? It's not 247, is it?

If so, is there anything else we haven't set the MTU right? Can you see what's wrong with the Settings?

[Francis Feng]

nrf connect changes the MTU to 247, sends it down to the device, and then the communication is always 251 bytes.

[ovrebekk]

Hi 

It seems like the ATT MTU is successfully changed to 247, but the data length is unchanged and remains at the default value of 27. 

Essentially the size of link layer packets and ATT packets is set separately in Bluetooth, and in order to send the entire attribute in one link layer packet the data length needs to be at least the size of the ATT packet + 4 (4 bytes is used by the link layer header). 

Are you using one of the standard examples for reference? If so can you let me which sample you are using, and which SDK version it is based on? 

Best regards
Torbjørn 

[Francis Feng]

SDK_15.3.0

[ovrebekk]

Hi 

And which example are you running? 

Do you think you can attach the trace file to the case so I can have a look at the full trace? 

Also, could you let me know what kind of device you are connecting to? 

Best regards
Torbjørn