"rf24server" by Juerd Waalboer

Very simple rf24-to-serial interface, designed for the Arduino Nano v3.

- First byte of packet payloads must be the number of bytes remaining.
- Only 32 of 40 address bits are used, so 0xFFFFFF is actually 0x00FFFFFF.
- The server is hard coded at 0x99669966.
- The bit rate is hard coded at 115200.
- Messages are limited to 15 bytes (16 including length field).

Receiving:
- Received packets are dumped on serial: hexadecimal string, followed by CRLF.
- The length field is not printed.

Sending:
- Send a hexadecimal string over serial, followed by any number of CR and/or LF.
- The first 4 bytes (8 hex digits) are used as the address to send to.
- The 5th byte is ignored.
- The remainder will be sent.

Connections:
- Arduino 3.3V to nRF24L01+ VCC
- Arduino GND  to nRF24L01+ GND
- Arduino   8  to nRF24L01+ CE
- Arduino  10  to nRF24L01+ CS
- Arduino  11  to nRF24L01+ MOSI
- Arduino  12  to nRF24L01+ MISO
- Arduino  13  to nRF24L01+ CLK