Data rate / throughput
Speaking of Bluetooth, there is a big difference between "Data Rate" (1MBit/s) and actual "Throughput" (which can be only 1/10 of that). Data transfer only happens during periodic intervals, not continuously. The BT physical layer is not comparable to a cable connection.
Furthermore there is some protocol overhead involved and some amount of post/pre-processing time for each packet.
Regarding the specs from the data sheet:
- 11k bps (BR/EDR)@ UART baud Rate is 115200 bps
- 8 Kbps (LE) UART baud Rate is 115200 bps
This is slightly irritating regarding the units. I am pretty sure (it also corresponds with the values from data sheet TABLE 10‐2) that those mean 11kByte/s and 8kByte/s for Bluetooth EDR (enhanced data rate) and Bluetooth LE (low energy) respectively.
Why the UART baud rate indication?
The most common UART framing (8N1) uses 2 bit per data byte overhead (start- and stop-bit).
So using 115200 baud, the actual throughput is only 92160 bps or 11520 Byte/s. This corresponds to the above mentioned 11kB/s. So when using Bluetooth EDR @115200 UART, the UART is the limiting factor!
Looking at the table "TABLE 10‐2: APP mode Throughput report" from the data sheet, the throughput is higher when using a higher UART baud rate. At higher baud rates, the Bluetooth connection is the limiting factor.
There is virtually no improvement (I can't explain why there even is one) when using a higher baud rate for Bluetooth LE, because it is already operating on its limit with 115200 baud UART.