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

1. Maximum number of packets per connection interval = [connection interval / Data_Packet_Time] where [] rounds to the highest whole number. So for example [7.5*1,000 microsecs / 2,468 microsecs] = 3 packets.

2. I'm sorry, but I'm not sure I understand what you mean. Feel free to use this formula to calculate throughput on your own.

3. Indeed, the 2MBPS PHY should result in ~2x the throughput, do you enable the 2MBPS in your application code? If so, and if both devices in the connection supports 2MBPS you should see an increase in throughput.

Best regards,

Simon

[Ridhi]

2). i have used :

27 bytes of ATT MTU 

158 bytes of ATT MTU 

247 bytes of ATT MTU 

my data length is 12 bytes and i took 2000 values of 1bytes each after 2 secs interval

Then what will be the throughput considering ATT_MTU , Connection Interval and number of packets per connection interval

3). how to enable 2M phy in connected mode in peripheral side?