RF12B.cpp

00001 #include "RF12B.h"
00002 
00003 #include "RF_defs.h"
00004 #include <algorithm>
00005 
00006 DigitalOut DBG3(LED3);
00007 
00008 RF12B::RF12B(PinName _SDI,
00009              PinName _SDO,
00010              PinName _SCK,
00011              PinName _NCS,
00012              PinName _NIRQ):spi(_SDI, _SDO, _SCK),
00013         NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ){// rfled(LED3) {
00014 
00015     /* SPI frequency, word lenght, polarity and phase */
00016     spi.format(16,0);
00017     spi.frequency(2000000);
00018 
00019     /* Set ~CS high */
00020     NCS = 1;
00021 
00022     /* Initialise RF Module */
00023     init();
00024 
00025     /* Setup interrupt to happen on falling edge of NIRQ */
00026     NIRQ.fall(this, &RF12B::rxISR);
00027     
00028     rxISR();
00029     
00030 }
00031 
00032 /* Returns the packet length if data is available in the receive buffer, 0 otherwise*/
00033 unsigned int RF12B::available() {
00034     return fifo.size();
00035 }
00036 
00037 /* Reads a packet of data, with length "size" Returns false if read failed. TODO: make a metafifo to isolate packets*/
00038 bool RF12B::read(unsigned char* data, unsigned int size) {
00039     if (fifo.size() == 0) {
00040         return false;
00041     } else {
00042         unsigned int i = 0;
00043         while (fifo.size() > 0 && i < size) {
00044             data[i++] = fifo.front();
00045             fifo.pop();
00046         }
00047         return true;
00048     }
00049 }
00050 
00051 /* Reads a byte of data from the receive buffer */
00052 unsigned char RF12B::read() {
00053     if (available()) {
00054         unsigned char data = fifo.front();
00055         fifo.pop();
00056         return data;
00057     } else {
00058         return 0xFF; // Error val although could also be data...
00059     }
00060 }
00061 
00062 /* Sends a packet of data to the RF module for transmission TODO: Make asych*/
00063 void RF12B::write(unsigned char *data, unsigned char length) {
00064     unsigned char crc = 0;
00065        
00066     /* Transmitter mode */
00067     changeMode(TX);
00068 
00069     writeCmd(0x0000);
00070     send(0xAA); // PREAMBLE
00071     send(0xAA);
00072     send(0xAA);
00073     send(0x2D); // SYNC
00074     send(0xD4);
00075     /* Packet Length */
00076     send(length);
00077     crc = crc8(crc, length);
00078     send(crc);
00079     crc = crc8(crc, crc);
00080     /* Packet Data */
00081     for (unsigned char i=0; i<length; i++) {
00082         send(data[i]);
00083         crc = crc8(crc, data[i]);
00084     }
00085     send(crc);
00086     send(0xAA); // DUMMY BYTES
00087     send(0xAA);
00088     send(0xAA);
00089 
00090     /* Back to receiver mode */
00091     changeMode(RX);
00092     status();
00093     
00094 
00095 }
00096 
00097 /* Transmit a 1-byte data packet */
00098 void RF12B::write(unsigned char data) {
00099     write(&data, 1);
00100 }
00101 
00102 void RF12B::write(queue<char> &data, int length) {
00103     char crc = 0;
00104     char length_byte = 0;
00105     
00106     /* -1 means try to transmit everything in the queue */
00107     if(length == -1) {
00108         length = data.size();
00109     }
00110     
00111     /* max length of packet is 255 */
00112     length_byte = min(length, 255);
00113     
00114     /* Transmitter mode */
00115     changeMode(TX);
00116 
00117     writeCmd(0x0000);
00118     send(0xAA); // PREAMBLE
00119     send(0xAA);
00120     send(0xAA);
00121     send(0x2D); // SYNC
00122     send(0xD4);
00123     /* Packet Length */
00124     send(length_byte);
00125     crc = crc8(crc, length_byte);
00126     send(crc);
00127     crc = crc8(crc, crc);
00128     /* Packet Data */
00129     for (char i=0; i<length_byte; i++) {
00130         send(data.front());
00131         crc = crc8(crc, data.front());
00132         data.pop();
00133     }
00134     send(crc);
00135     send(0xAA); // DUMMY BYTES
00136     send(0xAA);
00137     send(0xAA);
00138 
00139     /* Back to receiver mode */
00140     changeMode(RX);
00141     status();
00142 }
00143 
00144 /**********************************************************************
00145  *  PRIVATE FUNCTIONS
00146  *********************************************************************/
00147 
00148 /* Initialises the RF12B module */
00149 void RF12B::init() {
00150     /* writeCmd(0x80E7); //EL,EF,868band,12.0pF
00151      changeMode(RX);
00152      writeCmd(0xA640); //frequency select
00153      writeCmd(0xC647); //4.8kbps
00154      writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
00155      writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
00156      writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
00157      writeCmd(0xCED4); //SYNC=2DD4
00158      writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
00159      writeCmd(0x9850); //!mp,90kHz,MAX OUT
00160      writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT&#65533;CBW0
00161      writeCmd(0xE000); //NOT USED
00162      writeCmd(0xC800); //NOT USED
00163      writeCmd(0xC040); //1.66MHz,2.2V */
00164 
00165     writeCmd(
00166         RFM_CONFIG_EL           |
00167         RFM_CONFIG_EF           |
00168         RFM_CONFIG_BAND_433     //|
00169         //RFM_CONFIG_X_11_0pf // meh, using default
00170     );
00171 
00172     // 2. Power Management Command
00173     // leave everything switched off for now
00174     /*
00175     writeCmd(
00176         RFM_POWER_MANAGEMENT     // switch all off
00177     );
00178     */
00179 
00180     // 3. Frequency Setting Command
00181     writeCmd(
00182         RFM_FREQUENCY            |
00183         RFM_FREQ_433Band(435.7)  //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
00184     );
00185 
00186 
00187     // 4. Data Rate Command
00188     writeCmd(RFM_DATA_RATE_9600);
00189 
00190 
00191     // 5. Receiver Control Command
00192     writeCmd(
00193         RFM_RX_CONTROL_P20_VDI  |
00194         RFM_RX_CONTROL_VDI_FAST |
00195         //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
00196         RFM_RX_CONTROL_BW_134   |     // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
00197         RFM_RX_CONTROL_GAIN_0   |
00198         RFM_RX_CONTROL_RSSI_103      // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
00199     );
00200 
00201     // 6. Data Filter Command
00202     writeCmd(
00203         RFM_DATA_FILTER_AL      |
00204         RFM_DATA_FILTER_ML      |
00205         RFM_DATA_FILTER_DIG     //|
00206         //RFM_DATA_FILTER_DQD(4)
00207     );
00208 
00209     // 7. FIFO and Reset Mode Command
00210     writeCmd(
00211         RFM_FIFO_IT(8) |
00212         RFM_FIFO_DR    |
00213         0x8 //turn on 16bit sync word
00214     );
00215 
00216     // 8. FIFO Syncword
00217     // Leave as default: 0xD4
00218 
00219     // 9. Receiver FIFO Read
00220     // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
00221     // result = RFM_READ_FIFO();
00222 
00223     // 10. AFC Command
00224     writeCmd(
00225         //RFM_AFC_AUTO_VDI        |  //Note this might be changed to improve range. Refer to datasheet.
00226         RFM_AFC_AUTO_INDEPENDENT    |
00227         RFM_AFC_RANGE_LIMIT_7_8     |
00228         RFM_AFC_EN                  |
00229         RFM_AFC_OE                  |
00230         RFM_AFC_FI
00231     );
00232 
00233     // 11. TX Configuration Control Command
00234     writeCmd(
00235         RFM_TX_CONTROL_MOD_60 |
00236         RFM_TX_CONTROL_POW_0
00237     );
00238 
00239 
00240     // 12. PLL Setting Command
00241     writeCmd(
00242         0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
00243         // I think this will slow down the pll's reaction time. Not sure, check with someone!
00244     );
00245 
00246     changeMode(RX);
00247     resetRX();
00248     status();
00249 }
00250 
00251 /* Write a command to the RF Module */
00252 unsigned int RF12B::writeCmd(unsigned int cmd) {
00253     NCS = 0;
00254     unsigned int recv = spi.write(cmd);
00255     NCS = 1;
00256     return recv;
00257 }
00258 
00259 /* Sends a byte of data across RF */
00260 void RF12B::send(unsigned char data) {
00261     while (NIRQ);
00262     writeCmd(0xB800 + data);
00263 }
00264 
00265 /* Change the mode of the RF module to Transmitting or Receiving */
00266 void RF12B::changeMode(rfmode_t _mode) {
00267     mode = _mode;
00268     if (_mode == TX) {
00269         writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
00270     } else { /* mode == RX */
00271         writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
00272     }
00273 }
00274 
00275 /* Interrupt routine for data reception */
00276 void RF12B::rxISR() {
00277 
00278     printf("junk\r\n");
00279     DBG3 = 1;
00280     
00281     unsigned int data = 0;
00282     static int i = -2;
00283     static unsigned char packet_length = 0;
00284     static unsigned char crc = 0;
00285     static queue<unsigned char> temp;
00286     
00287     
00288 
00289     //Loop while interrupt is asserted
00290     while (!NIRQ_in && mode == RX) {
00291         
00292         /* Grab the packet's length byte */
00293         if (i == -2) {
00294             data = writeCmd(0x0000);
00295             if ( (data&0x8000) ) {
00296                 data = writeCmd(0xB000);
00297                 packet_length = (data&0x00FF);
00298                 crc = crc8(crc, packet_length);
00299                 i++;
00300             }
00301         }
00302 
00303         //If we exhaust the interrupt, exit
00304         if (NIRQ_in)
00305             break;
00306 
00307         // Check that packet length was correct
00308         if (i == -1) {
00309             data = writeCmd(0x0000);
00310             if ( (data&0x8000) ) {
00311                 data = writeCmd(0xB000);
00312                 unsigned char crcofsize = (data&0x00FF);
00313                 if (crcofsize != crc) {
00314                     //It was wrong, start over
00315                     i = -2;
00316                     packet_length = 0;
00317                     crc = 0;
00318                     temp = queue<unsigned char>();
00319                     resetRX();
00320                 } else {
00321                     crc = crc8(crc, crcofsize);
00322                     i++;
00323                 }
00324             }
00325         }
00326 
00327         //If we exhaust the interrupt, exit
00328         if (NIRQ_in)
00329             break;
00330 
00331         /* Grab the packet's data */
00332         if (i >= 0 && i < packet_length) {
00333             data = writeCmd(0x0000);
00334             if ( (data&0x8000) ) {
00335                 data = writeCmd(0xB000);
00336                 temp.push(data&0x00FF);
00337                 crc = crc8(crc, (unsigned char)(data&0x00FF));
00338                 i++;
00339             }
00340         }
00341 
00342         //If we exhaust the interrupt, exit
00343         if (NIRQ_in)
00344             break;
00345 
00346         if (i >= packet_length) {
00347             data = writeCmd(0x0000);
00348             if ( (data&0x8000) ) {
00349                 data = writeCmd(0xB000);
00350                 if ((unsigned char)(data & 0x00FF) == crc) {
00351                     //If the checksum is correct, add our data to the end of the output buffer
00352                     while (!temp.empty()) {
00353                         fifo.push(temp.front());
00354                         temp.pop();
00355                     }
00356                 }
00357 
00358                 /* Tell RF Module we are finished, and clean up */
00359                 i = -2;
00360                 packet_length = 0;
00361                 crc = 0;
00362                 temp = queue<unsigned char>();
00363                 resetRX();
00364             }
00365         }
00366     }    
00367 }
00368 
00369 unsigned int RF12B::status() {
00370     return writeCmd(0x0000);
00371 }
00372 
00373 /* Tell the RF Module this packet is received and wait for the next */
00374 void RF12B::resetRX() {
00375     writeCmd(0xCA81);
00376     writeCmd(0xCA83);
00377 };
00378 
00379 /* Calculate CRC8 */
00380 unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
00381     crc = crc ^ data;
00382     for (int i = 0; i < 8; i++) {
00383         if (crc & 0x01) {
00384             crc = (crc >> 1) ^ 0x8C;
00385         } else {
00386             crc >>= 1;
00387         }
00388     }
00389     return crc;
00390 }