Throughput ATT_MTU

[Ridhi]

We are using nrf52832 soc for our product development and using that we are trying to increase the throughput of our device using the information from the following forum:
Novel Bits throughput guide 
In this forum it states that the Maximum GATT MTU SIZE possible is 247 bytes in which 244 bytes of data is the actual payload size and if the data is greater than the limit, then it will split into multiple packets. So we tried to send more that 247 bytes of data just to check how the data split in multiple packet is working. We tried to sent 256 bytes of data and we were able to get 255 bytes of data without any splitting, which is more than 247 bytes. So we are wondering what is the Maximum GATT MTU SIZE possible in nrf52832 soc. 
We also looked into the throughput example provided by the nordic (ble_app_att_mtu) and in that MTU size is set to 247 and data length is set to 251 which is less that what we are able to send from nrf52832 to phone, is there any possible explanation for this?

[Simonr]

Hi

Thanks, it seems from the sniffer trace that the central gives a larger window size in LL_CONNECTION_UPDATE_IND on the 1MBPS trace compared to the 2MBPS trace. Do you do anything to set this from the central side in either case? Either the phone is doing something to the connection window automatically when moving to the 2MBPS PHY, or there is something with how you have set up the 2MBPS PHY on the peripheral side. 

When testing the throughput example in the past we haven't had an issue with the 2MBPS mode being slower sa far as I know. Can you send us your project so we can test it on our end perhaps?

Best regards,

Simon

[Ridhi]

No am not changing anything on the central side. I am finding it very difficult because my task is to compare throughput between LE 2m and Le 1m. But from readings LE 1M works as expected but le 2 M is not.

my project is using SHT40 sensor and external flash. How will you test it