File content as of revision 2:298924eb2b41:

#include "beacon.h"
Serial pc(USBTX, USBRX);          // tx, rx
SPI spi(D11, D12, D13);              // mosi, miso, sclk
//SPI spi(PTA16, PTA17, PTA15);              // mosi, miso, sclk
DigitalOut cs(D10);                //slave select or chip select

void writereg(uint8_t reg,uint8_t val)
{
    cs = 0;__disable_irq();spi.write(reg | 0x80);spi.write(val);__enable_irq();cs = 1;
}
uint8_t readreg(uint8_t reg)
{
    int val;cs = 0;__disable_irq();spi.write(reg & ~0x80);val = spi.write(0);__enable_irq();cs = 1;return val;
}
void clearTxBuf()
{
    writereg(RF22_REG_08_OPERATING_MODE2,0x01);
    writereg(RF22_REG_08_OPERATING_MODE2,0x00);
}
void clearRxBuf()
{
    writereg(RF22_REG_08_OPERATING_MODE2,0x02);
    writereg(RF22_REG_08_OPERATING_MODE2,0x00);
}
int setFrequency(float centre,float afcPullInRange)
{
//freq setting begins 
    uint8_t fbsel = 0x40;
    uint8_t afclimiter;
    if (centre >= 480.0) {
        centre /= 2;
        fbsel |= 0x20;
        afclimiter = afcPullInRange * 1000000.0 / 1250.0;
    } else {
        if (afcPullInRange < 0.0 || afcPullInRange > 0.159375)
            return false;
        afclimiter = afcPullInRange * 1000000.0 / 625.0;
    }
    centre /= 10.0;
    float integerPart = floor(centre);
    float fractionalPart = centre - integerPart;
 
    uint8_t fb = (uint8_t)integerPart - 24; // Range 0 to 23
    fbsel |= fb;
    uint16_t fc = fractionalPart * 64000;
    writereg(RF22_REG_73_FREQUENCY_OFFSET1, 0);  // REVISIT
    writereg(RF22_REG_74_FREQUENCY_OFFSET2, 0);
    writereg(RF22_REG_75_FREQUENCY_BAND_SELECT, fbsel);
    writereg(RF22_REG_76_NOMINAL_CARRIER_FREQUENCY1, fc >> 8);
    writereg(RF22_REG_77_NOMINAL_CARRIER_FREQUENCY0, fc & 0xff);
    writereg(RF22_REG_2A_AFC_LIMITER, afclimiter);
    return 0;
}

void init()
{
    //reset()
    writereg(RF22_REG_07_OPERATING_MODE1,0x80);        //sw_reset
    wait(1);                    //takes time to reset                                  

    clearTxBuf();                                                             
    clearRxBuf();                                                             
    //txfifoalmostempty
    writereg(RF22_REG_7D_TX_FIFO_CONTROL2,10);
    //rxfifoalmostfull
    writereg(RF22_REG_7E_RX_FIFO_CONTROL,20);
    //Packet-engine registers
    writereg(RF22_REG_30_DATA_ACCESS_CONTROL,0x00);    //RF22_REG_30_DATA_ACCESS_CONTROL, RF22_ENPACRX | RF22_ENPACTX | RF22_ENCRC | RF22_CRC_CRC_16_IBM
    //0x00
    
    
    //writereg(RF22_REG_32_HEADER_CONTROL1,0x88);    //RF22_REG_32_HEADER_CONTROL1, RF22_BCEN_HEADER3 | RF22_HDCH_HEADER3  //not reqiured for tx
    writereg(RF22_REG_33_HEADER_CONTROL2,0x08);    //RF22_REG_33_HEADER_CONTROL2, RF22_HDLEN_4 | RF22_SYNCLEN_2
    //why 0x42 //or 0x00??
    
    writereg(RF22_REG_34_PREAMBLE_LENGTH,0x00);       //RF22_REG_34_PREAMBLE_LENGTH, nibbles); preamble length = 8;
    //why is preamble used??
    
    //writereg(RF22_REG_36_SYNC_WORD3,0x2D);    //syncword3=2D
    //why??
    
    //writereg(RF22_REG_37_SYNC_WORD2,0xD4);    //syncword2=D4
    //why??
    
    //writereg(RF22_REG_3F_CHECK_HEADER3,0);    //RF22_REG_3F_CHECK_HEADER3, RF22_DEFAULT_NODE_ADDRESS
    
    
    //why all these headers
    //writereg(RF22_REG_3A_TRANSMIT_HEADER3,0xab);    //header_to
    //writereg(RF22_REG_3B_TRANSMIT_HEADER2,0xbc);    //header_from 
    //writereg(RF22_REG_3C_TRANSMIT_HEADER1,0xcd);    //header_ids
    //writereg(RF22_REG_3D_TRANSMIT_HEADER0,0xde);    //header_flags
    //writereg(RF22_REG_3F_CHECK_HEADER3,0xab);   
    //writereg(RF22_REG_40_CHECK_HEADER2,0xbc);   
    //writereg(RF22_REG_41_CHECK_HEADER1,0xcd);   
    //writereg(RF22_REG_42_CHECK_HEADER0,0xde);
    
    //RSSI threshold for clear channel indicator //rx
    //writereg(RF22_REG_27_RSSI_THRESHOLD,0xA5);         //55 for -80dBm, 2D for -100dBm, 7D for -60dBm, A5 for -40dBm, CD for -20 dBm
    
    writereg(RF22_REG_0B_GPIO_CONFIGURATION0,0x15); // TX state                        ??
    writereg(RF22_REG_0C_GPIO_CONFIGURATION1,0x12); // RX state                        ??
    
    //interrupts
    // spiWrite(RF22_REG_05_INTERRUPT_ENABLE1, RF22_ENTXFFAEM |RF22_ENRXFFAFULL | RF22_ENPKSENT |RF22_ENPKVALID| RF22_ENCRCERROR);
    // spiWrite(RF22_REG_06_INTERRUPT_ENABLE2, RF22_ENPREAVAL);
    
    setFrequency(435.0, 0.05);//check
    
    //return !(statusRead() & RF22_FREQERR);
    if((readreg(RF22_REG_02_DEVICE_STATUS)& 0x08)!= 0x00)
    pc.printf("frequency not set properly\n");
    //frequency set

    //setModemConfig(FSK_Rb2_4Fd36);       FSK_Rb2_4Fd36,       ///< FSK, No Manchester, Rb = 2.4kbs,  Fd = 36kHz
    //setmodemregisters
    //0x1b, 0x03, 0x41, 0x60, 0x27, 0x52, 0x00, 0x07, 0x40, 0x0a, 0x1e, 0x80, 0x60, 0x13, 0xa9, 0x2c, 0x22, 0x3a = FSK_RB2_4FD36
    //0xc8, 0x03, 0x39, 0x20, 0x68, 0xdc, 0x00, 0x6b, 0x2a, 0x08, 0x2a, 0x80, 0x60, 0x13, 0xa9, 0x2c, 0x21, 0x08 = OOK,2.4, 335
    writereg(RF22_REG_1C_IF_FILTER_BANDWIDTH,0xdf);
    writereg(RF22_REG_1F_CLOCK_RECOVERY_GEARSHIFT_OVERRIDE,0x03);
    writereg(RF22_REG_20_CLOCK_RECOVERY_OVERSAMPLING_RATE,0x39);
    writereg(RF22_REG_21_CLOCK_RECOVERY_OFFSET2,0x20);                     
    writereg(RF22_REG_22_CLOCK_RECOVERY_OFFSET1,0x68);           //updated 20 to 25 reg values from excel sheet for 1.2 Khz freq. deviation,fsk
    writereg(RF22_REG_23_CLOCK_RECOVERY_OFFSET0,0xdc);
    writereg(RF22_REG_24_CLOCK_RECOVERY_TIMING_LOOP_GAIN1,0x00);
    writereg(RF22_REG_25_CLOCK_RECOVERY_TIMING_LOOP_GAIN0,0x6B);
    writereg(RF22_REG_2C_OOK_COUNTER_VALUE_1,0x2C);
    writereg(RF22_REG_2D_OOK_COUNTER_VALUE_2,0x11);    //not required for fsk (OOK counter value)
    writereg(RF22_REG_2E_SLICER_PEAK_HOLD,0x2A);         //??
    writereg(RF22_REG_58,0x80);
    writereg(RF22_REG_69_AGC_OVERRIDE1,0x60);
    
    //check...//also depends on 0x70[5]
    writereg(RF22_REG_6E_TX_DATA_RATE1,0x09);//TX at 0.123kbps=:6E=0x01; 6F=0x02 
    writereg(RF22_REG_6F_TX_DATA_RATE0,0xd5);//TX at 1.2kbps: 6E=0x09; 6F=0xd5    //Formula:  tx_datarate*(2^21)/10^6
    //
    
    writereg(RF22_REG_70_MODULATION_CONTROL1,0x2c);
    writereg(RF22_REG_71_MODULATION_CONTROL2,0x21);//ook = 0x21 //fsk = 0x22
    
    //writereg(RF22_REG_72_FREQUENCY_DEVIATION,0x50);
    //required for OOK???
    
    //set tx power
    writereg(RF22_REG_6D_TX_POWER,0x07);    //20dbm
    //why 0x06?? 0x07 is for max//is the previous bits required?
    
    //writereg(RF22_REG_6D_TX_POWER,0x00);    //-1dbm
    //writereg(RF22_REG_3E_PACKET_LENGTH,TX_DATA); //packet length
    //packet length not required
         
}
int main()
{
    wait(1);                     // wait for POR to complete   //change the timing later
    cs=1;                          // chip must be deselected
    wait(1);                    //change the time later
    spi.format(8,0);
    spi.frequency(10000000);       //10MHz SCLK    
    if (readreg(RF22_REG_00_DEVICE_TYPE) == 0x08) pc.printf("spi connection valid\n");
    else pc.printf("error in spi connection\n");

    init();

    
    //init complete
    pc.printf("init complete.....press t to send\n");
    
    
    //********

while(pc.getc()=='t')   //1
{ 
   /*uint8_t data[] = "Hello World!";
    pc.printf("%d %d %d %d %d %d %d %d %d %d %d %d",data[0],data[1],data[2],data[3],data[4],data[5],data[6],data[7],data[8],data[9],data[10],data[11],data[12]);*/
    
    uint8_t data[255];              //starts from 0,1,2,3,4!!!;   
    int i = 0;                           //for loops
    int u = 0;                           //universal count for hk array
    int bar = 0; 
    //filling hk data
    /*for(int n=0; n<1; n++)
        data[n] = 0xAA;
        data[1] = 0x3A;    */
    //for(int n=0; n<15; n++) 
        /*data[0] = 0xAB;
        data[1] = 0x8A;
        data[2] = 0xE2;
        data[3] = 0xBB;
        data[4] = 0xB8;
        data[5] = 0xA2;
        data[6] = 0x8E;
        data[7] = 0x88;
        data[8] = 0x99;
        data[9] = 0xAA;
        data[10] = 0xAA;
        data[11] = 0xAA;
        data[12] = 0xDD;
        data[13] = 0xEE;
        data[14] = 0x00;
        */
    /*for(int n=50; n<60; n++)
        data[n] = n;   */
    //for(int n=60; n<120; n++)
      //  data[n] = 0x11;    
    /*for(int n=75; n<97; n++)
        data[n] = 0xBC;
    for(int n=97; n<110; n++)
        data[n] = 0xEC;
    for(int n=110; n<120; n++)
        data[n] = 0xFC; */
    for(int n=0; n<255; n++)
        data[n] = 0xAB;
        /*uint8_t stuff[] = "IITMSAT IITMSAT";
        for(int i = 0 ; i < 15 ; ++i){
            data[i] = stuff[i];
        }*/

    //for(int n=150; n<TX_DATA; n++)
      //  data[n] = 0x11;
    //tx settings begin

    //setModeIdle();
    writereg(RF22_REG_07_OPERATING_MODE1,0x01);        //ready mode
    //fillTxBuf(data, len);
    clearTxBuf();  
    //Filling Data into FIFO for the first time
    /*cs = 0;
        spi.write(0xFF);               //fifo write access
        for(i=0; i<datalen; i++){
            spi.write(data[i]);
            pc.printf("0x%X \n",data[u+i]);
            }
        u=i;//check its 64
        cs = 1;       */
        
    //Set to Tx mode
    writereg(RF22_REG_07_OPERATING_MODE1,0x09);

    //Check for fifoempty Thresh
    while((readreg(RF22_REG_03_INTERRUPT_STATUS1) & 0x20) != 0x20);

    while(u!=TX_DATA) {
        if((TX_DATA - u) >= TIMES)
            bar = TIMES;
        else
            bar = (TX_DATA - u);

    //writing again
        cs = 0;
        spi.write(0xFF);                   //FIFO write access
        for(i=0; i<bar; i++,u++)
        {
            
            //spi.write(data[i]);
            spi.write(0xAA) ;
            //pc.printf("0x%X 0x%X \r\n",data[i],u);
            }
        //u = u + i;
        cs = 1;
        //Check for fifoThresh
        while((readreg(RF22_REG_03_INTERRUPT_STATUS1) & 0x20) != 0x20);
    }    
    //rf22.waitPacketSent();
    while((readreg(RF22_REG_03_INTERRUPT_STATUS1) & 0x04) != 0x04)pc.printf(" chck pkt sent!\n");     
    pc.printf(" packet sent ");
    
}
}