Well, BT specification is stacked like most communication protocol families; meaning that a higher version of the standard also supports the lower version standards.
Hence you could imagine that if a device supports 4.0 it will also co-work with 2.1.
However, this only applies to comunication master nodes. (like computers, mobile phones and tablets) Communication slave nodes can and often are implementing only part of the standard.

This is exactly case with battery-concious slave nodes, if specification says they implement BT4.0 it most certainly means they only implement the BT4.0LE ( = low energy ) standard. LE is significantly less-power-hungry than normal BT connection, allowing small devices with tiny batteries last for weeks/months usage.

The HW of N9 supports BT4.0LE, but drivers for it are missing in the default shape it comes in.


Could be
What is needed are basically 3 things;

• It needs to be checked whether the FW blob supports the LE mode. (that's the binary file that's loaded to the chipset to make it work) If it does not, we'll need to get the binary from somewhere.
• Kernel driver needs to be updated to latest BlueZ release.
• User mode tools need to be updated

If the previous 3 things are set up correctly, sure.


Well the rest is just application development, that's outside my domain really