I'd love to show you how I finally got around sending MIDI over these cheap NRF24l01 modules.
I have been wanting to try wireless MIDI for a long time and the other week came across some code for a wireless MIDI pads and joystick controller which controlled pitchbend commands. ( see here https://github.com/honnet/BAD
The transmitter is working on an Arduino MEGA2560 and the reciever on a duemilanove. I have made a shield for the NRF24l01 module using a protoshield with a MIDI din attached for simplicity and it is quite robust.
After studying the code I worked out how to change it to suit 3 pots, an LDR and 2 buttons to trigger noteon/off messages. Oh yeah, the original code used a USBMIDI library which I changed to a standard MIDI library. I initially had some problems with understanding how the NRF24l01s transmitted their information payload but after some help, worked out how to change the payload to reflect the information sent by the controlers and buttons.
Another problem was with getting the transmitter to transmit in increments of 1 ( which originally it was doing in 3 so intead of controller messages going up: 1,2,3,4,5....etc they were going up 1,4,7,10...etc)
The code works and is very smooth, the pots and LDR are connected to A0,A1,A2 and A3 and the note buttons digital pins 18 and 19 . Have a look at the pictures.
I will post the code in another message as I will probably run out of characters if I try to post it on this one..
All the best,
Steve ( Mubase )