How to achieve 2Mbps data rate?

[qoolink]

Int the website:

link text

FEATURES show the nordice nRF51822 has 3 data rates (2Mbps/1Mbps/250kbps).

But , I set

number of packets transmitted per connection event 20

Connection interval 7.5

I can't achieve 2Mbps throughput ?

[RK]

There is no BLE with 'proprietary protocol', you're either using BLE, or you're not using BLE. BLE is defined over an underlying 1Mbps link, however the actual throughput after you take into consideration

1. The overhead of the protocol
2. The fact the link is half-duplex
3. The limitations in BTLE stacks (all of them) which restrict the number of packets which can be transmitted per connection interval
4. The limitations of various communicating devices which may limit how often devices connect
5. Whether you are writing packets requiring responses or writing without response and dealing with dropped packets.

This thread does a good job of summarising what's actually even possible

devzone.nordicsemi.com/.../

with the best combination available it's about .5Mbps

[RK]

Sorry brain entirely not working and I copied the wrong number from an entirely different mail about something else.

I was wondering what the theoretical overhead is - largest packet is 376us, full-sized non-ecrypted packets are 344us, smallest is 80us, you need one packet in each direction consecutively so that's 424us and that sends 20 bytes of data one-way. That leads to a theoretical max of 47kB/s. The requirement to end the connection event in time to let the radios switch cuts that down and it's further cut down by various implementations restricting the number of packets per connection interval and the min spacing between them.

It's not very fast, but it wasn't designed to be that fast.