Hello.

I have read the datasheet and looked into the corresponding position in the sourcecode of "RF12.cpp".

Additionally, and the really helpful source!!!, I received great help from a electronic engineer.

More detailed:

Look the definition of "uint8_t rf12_initialize (uint8_t id, uint8_t band, uint8_t g)" in RF12.cpp, this function is used to initialize teh RFM12(B) module.

Then, I want to know what paramter has to be changed, of course it was "band" (uint8_t), it was only used once in the function rf12_initialize. That means that this position is the corresponding one to be examined:

rf12_xfer(0x80C7 | (band << 4));

(RF12.cpp, l.404)

Look here:

"|" is the logical AND operator, << is a bitshift operator (shifts 4 to the left, that means a hexadecimal unit (2^4=16))

Now consider binary:

1000 0000 1100 0111

Now I need the datasheet (

hoperf : RFM12.pdf ) , see the bottom left table on page 12.

Back to the binary code:

I said << is the bitshift operator, lets apply it on the code, e.g. we use "2" as given in the definition (#define RF12_868MHZ 2) for 868MHz band. Then it is

**0000 0010 << 4** ("shift" the 10 ,which is 2 in binary, 4 bits left) =

**0010 0000** .

Now do the addition:

0000 0000

**0010 **0000 + 1000 0000

**1100 **0111 = 1000 0000

**1110 **0111

The important binary parts were highlighted.

In the datasheet's table there is written:

315MHz band: b0=0; b1=0. That means we need a zero for both b0 and b1.

That is 1000 0000 11

**00 **0111 .

And it is a lot of fun!

Feel free to ask if there are any questions (maybe explanation was unclear because quickly written).

Regards.