File content as of revision 4:2a295db9ba1a:

#include "RF12B.h"

RF12B::RF12B(PinName _SDI,
             PinName _SDO,
             PinName _SCK,
             PinName _NCS,
             PinName _NIRQ):spi(_SDI, _SDO, _SCK),
        NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ) {

    /* SPI frequency, word lenght, polarity and phase */
    spi.format(16,0);
    spi.frequency(2000000);

    /* Set ~CS high */
    NCS = 1;

    /* Initialise RF Module */
    init();
    resetRX();

    /* Setup interrupt to happen on falling edge of NIRQ */
    NIRQ.fall(this, &RF12B::rxISR);
}

/* Returns true if receive buffer contains data */
bool RF12B::available() {
    return !fifo.empty();
}

/* Reads a byte of data from the receive buffer */
unsigned char RF12B::read() {
    if (available()) {
        unsigned char data = fifo.front();
        fifo.pop();
        return data;
    } else {
        return 0xFF; // Error val although could also be data...
    }
}

/* Sends a byte of data to the RF module for transmission */
void RF12B::write(unsigned char *data, unsigned char length) {
    /* Transmitter mode */
    changeMode(TX);

    writeCmd(0x0000);
    send(0xAA); // PREAMBLE
    send(0xAA);
    send(0xAA);
    send(0x2D); // SYNC
    send(0xD4);
    /* Packet Length */
    send(length);
    /* Packet Data */
    for (unsigned char i=0; i<length; i++) {
        send(data[i]);
    }
    send(0xAA); // DUMMY BYTES
    send(0xAA);
    send(0xAA);

    /* Back to receiver mode */
    changeMode(RX);
}

/* Transmit a 1-byte data packet */
void RF12B::write(unsigned char data) {
    write(&data, 1);
}

/**********************************************************************
 *  PRIVATE FUNCTIONS
 *********************************************************************/

/* Initialises the RF12B module */
void RF12B::init() {
    writeCmd(0x80E7); //EL,EF,868band,12.0pF
    changeMode(RX);
    writeCmd(0xA640); //frequency select
    writeCmd(0xC647); //4.8kbps
    writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
    writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
    writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
    writeCmd(0xCED4); //SYNC=2DD4
    writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
    writeCmd(0x9850); //!mp,90kHz,MAX OUT
    writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT�CBW0
    writeCmd(0xE000); //NOT USED
    writeCmd(0xC800); //NOT USED
    writeCmd(0xC040); //1.66MHz,2.2V
}

/* Write a command to the RF Module */
unsigned int RF12B::writeCmd(unsigned int cmd) {
    NCS = 0;
    unsigned int recv = spi.write(cmd);
    NCS = 1;
    return recv;
}

/* Sends a byte of data across RF */
void RF12B::send(unsigned char data) {
    while (NIRQ);
    writeCmd(0xB800 + data);
}

/* Change the mode of the RF module to Transmitting or Receiving */
void RF12B::changeMode(rfmode_t mode) {
    if (mode == TX) {
        writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
    } else { /* mode == RX */
        writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
    }
}

/* Interrupt routine for data reception */
void RF12B::rxISR() {
    unsigned int data = 0, i = 0;
    unsigned char packet_length = 0;

    /* Grab the packet's length byte */
    data = writeCmd(0x0000);
    if ( (data&0x8000) ) {
        data = writeCmd(0xB000);
        packet_length = (data&0x00FF);
    }
    
    /* Grab the packet's data */
    while ((++i) < packet_length) {
        data = writeCmd(0x0000);
        if ( (data&0x8000) ) {
            data = writeCmd(0xB000);
            fifo.push(data&0x00FF);
        }
    }
    /* Tell RF Module we are finished */
    resetRX();
}

/* Tell the RF Module this packet is received and wait for the next */
void RF12B::resetRX() {
    writeCmd(0xCA81);
    writeCmd(0xCA83);
};