RF12B.cpp

00001 #include "RF12B.h"
00002 
00003 #include "RF_defs.h"
00004 #include <algorithm>
00005 #include "system.h"
00006 #include "globals.h"
00007 
00008 
00009 RF12B::RF12B(PinName _SDI,
00010              PinName _SDO,
00011              PinName _SCK,
00012              PinName _NCS,
00013              PinName _NIRQ):spi(_SDI, _SDO, _SCK),
00014         NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ) {// rfled(LED3) {
00015 
00016     // SPI frequency, word lenght, polarity and phase */
00017     spi.format(16,0);
00018     spi.frequency(2000000);
00019 
00020     // Set ~CS high 
00021     NCS = 1;
00022 
00023     // Initialise RF Module 
00024     init();
00025 
00026     // Setup interrupt to happen on falling edge of NIRQ 
00027     NIRQ.fall(this, &RF12B::rxISR);
00028 }
00029 
00030 // Returns the packet length if data is available in the receive buffer, 0 otherwise
00031 //unsigned int RF12B::available() {
00032 //    return fifo.size();
00033 //}
00034 
00035 // Reads a packet of data, with length "size" Returns false if read failed. TODO: make a metafifo to isolate packets
00036 /*bool RF12B::read(unsigned char* data, unsigned int size) {
00037     if (fifo.size() == 0) {
00038         return false;
00039     } else {
00040         unsigned int i = 0;
00041         while (fifo.size() > 0 && i < size) {
00042             data[i++] = fifo.front();
00043             fifo.pop();
00044         }
00045         return true;
00046     }
00047 }
00048 */
00049 
00050 // Reads a byte of data from the receive buffer 
00051 /*
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 
00063 // Sends a packet of data to the RF module for transmission TODO: Make asych
00064 void RF12B::write(unsigned char *data, unsigned char length) {
00065     unsigned char crc = 0;
00066 
00067     // Transmitter mode 
00068     changeMode(TX);
00069 
00070     writeCmd(0x0000);
00071     send(0xAA); // PREAMBLE
00072     send(0xAA);
00073     send(0xAA);
00074     send(0x2D); // SYNC
00075     send(0xD4);
00076     // Packet Length 
00077     send(length);
00078     crc = crc8(crc, length);
00079     send(crc);
00080     crc = crc8(crc, crc);
00081     // Packet Data 
00082     for (unsigned char i=0; i<length; i++) {
00083         send(data[i]);
00084         crc = crc8(crc, data[i]);
00085     }
00086     send(crc);
00087     send(0xAA); // DUMMY BYTES
00088     send(0xAA);
00089     send(0xAA);
00090 
00091     // Back to receiver mode 
00092     changeMode(RX);
00093     status();
00094 
00095 
00096 }
00097 
00098 // Transmit a 1-byte data packet 
00099 void RF12B::write(unsigned char data) {
00100     write(&data, 1);
00101 }
00102 /*
00103 void RF12B::write(queue<char> &data, int length) {
00104     char crc = 0;
00105     char length_byte = 0;
00106 
00107     // -1 means try to transmit everything in the queue 
00108     if (length == -1) {
00109         length = data.size();
00110     }
00111 
00112     // max length of packet is 255 
00113     length_byte = min(length, 255);
00114 
00115     // Transmitter mode 
00116     changeMode(TX);
00117 
00118     writeCmd(0x0000);
00119     send(0xAA); // PREAMBLE
00120     send(0xAA);
00121     send(0xAA);
00122     send(0x2D); // SYNC
00123     send(0xD4);
00124     // Packet Length 
00125     send(length_byte);
00126     crc = crc8(crc, length_byte);
00127     send(crc);
00128     crc = crc8(crc, crc);
00129     // Packet Data 
00130     for (char i=0; i<length_byte; i++) {
00131         send(data.front());
00132         crc = crc8(crc, data.front());
00133         data.pop();
00134     }
00135     send(crc);
00136     send(0xAA); // DUMMY BYTES
00137     send(0xAA);
00138     send(0xAA);
00139 
00140     // Back to receiver mode 
00141     changeMode(RX);
00142     status();
00143 }
00144 */
00145 /**********************************************************************
00146  *  PRIVATE FUNCTIONS
00147  *********************************************************************/
00148 
00149 // Initialises the RF12B module 
00150 void RF12B::init() {
00151     // writeCmd(0x80E7); //EL,EF,868band,12.0pF
00152      changeMode(RX);
00153      writeCmd(0xA640); //frequency select
00154      writeCmd(0xC647); //4.8kbps
00155      writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
00156      writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
00157      writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
00158      writeCmd(0xCED4); //SYNC=2DD4
00159      writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
00160      writeCmd(0x9850); //!mp,90kHz,MAX OUT
00161      writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT&#65533;CBW0
00162      writeCmd(0xE000); //NOT USED
00163      writeCmd(0xC800); //NOT USED
00164      writeCmd(0xC040); //1.66MHz,2.2V 
00165 
00166     writeCmd(
00167         RFM_CONFIG_EL           |
00168         RFM_CONFIG_EF           |
00169         RFM_CONFIG_BAND_433     //|
00170         //RFM_CONFIG_X_11_0pf // meh, using default
00171     );
00172 
00173     // 2. Power Management Command
00174     // leave everything switched off for now
00175     /*
00176     writeCmd(
00177         RFM_POWER_MANAGEMENT     // switch all off
00178     );
00179     */
00180 
00181     // 3. Frequency Setting Command
00182     writeCmd(
00183         RFM_FREQUENCY            |
00184         RFM_FREQ_433Band(435.7)  //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
00185     );
00186 
00187 
00188     // 4. Data Rate Command
00189     //writeCmd(RFM_DATA_RATE_9600);
00190     writeCmd(RFM_DATA_RATE_57600);
00191 
00192 
00193     // 5. Receiver Control Command
00194     writeCmd(
00195         RFM_RX_CONTROL_P20_VDI  |
00196         RFM_RX_CONTROL_VDI_FAST |
00197         //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
00198         RFM_RX_CONTROL_BW_134   |     // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
00199         RFM_RX_CONTROL_GAIN_0   |
00200         RFM_RX_CONTROL_RSSI_103      // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
00201     );
00202 
00203     // 6. Data Filter Command
00204     writeCmd(
00205         RFM_DATA_FILTER_AL      |
00206         RFM_DATA_FILTER_ML      |
00207         RFM_DATA_FILTER_DIG     //|
00208         //RFM_DATA_FILTER_DQD(4)
00209     );
00210 
00211     // 7. FIFO and Reset Mode Command
00212     writeCmd(
00213         RFM_FIFO_IT(8) |
00214         RFM_FIFO_DR    |
00215         0x8 //turn on 16bit sync word
00216     );
00217 
00218     // 8. FIFO Syncword
00219     // Leave as default: 0xD4
00220 
00221     // 9. Receiver FIFO Read
00222     // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
00223     // result = RFM_READ_FIFO();
00224 
00225     // 10. AFC Command
00226     writeCmd(
00227         //RFM_AFC_AUTO_VDI        |  //Note this might be changed to improve range. Refer to datasheet.
00228         RFM_AFC_AUTO_INDEPENDENT    |
00229         RFM_AFC_RANGE_LIMIT_7_8     |
00230         RFM_AFC_EN                  |
00231         RFM_AFC_OE                  |
00232         RFM_AFC_FI
00233     );
00234 
00235     // 11. TX Configuration Control Command
00236     writeCmd(
00237         RFM_TX_CONTROL_MOD_60 |
00238         RFM_TX_CONTROL_POW_0
00239     );
00240 
00241 
00242     // 12. PLL Setting Command
00243     writeCmd(
00244         0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
00245         // I think this will slow down the pll's reaction time. Not sure, check with someone!
00246     );
00247 
00248     changeMode(RX);
00249     resetRX();
00250     status();
00251 }
00252 
00253 /* Write a command to the RF Module */
00254 unsigned int RF12B::writeCmd(unsigned int cmd) {
00255     NCS = 0;
00256     unsigned int recv = spi.write(cmd);
00257     NCS = 1;
00258     return recv;
00259 }
00260 
00261 /* Sends a byte of data across RF */
00262 void RF12B::send(unsigned char data) {
00263     while (NIRQ);
00264     writeCmd(0xB800 + data);
00265 }
00266 
00267 /* Change the mode of the RF module to Transmitting or Receiving */
00268 void RF12B::changeMode(rfmode_t _mode) {
00269     mode = _mode;
00270     if (_mode == TX) {
00271         writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
00272     } else { /* mode == RX */
00273         writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
00274     }
00275 }
00276 
00277 // Interrupt routine for data reception */
00278 void RF12B::rxISR() {
00279 
00280     unsigned int data = 0;
00281     static int i = -2;
00282     static unsigned char packet_length = 0;
00283     static unsigned char crc = 0;
00284 //    #ifdef ROBOT_SECONDARY
00285     static unsigned char temp;
00286 //    #endif
00287 
00288     //Loop while interrupt is asserted
00289     while (!NIRQ_in && mode == RX) {
00290 
00291         // Grab the packet's length byte
00292         if (i == -2) {
00293             data = writeCmd(0x0000);
00294             if ( (data&0x8000) ) {
00295                 data = writeCmd(0xB000);
00296                 packet_length = (data&0x00FF);
00297                 crc = crc8(crc, packet_length);
00298                 i++;
00299             }
00300         }
00301 
00302         //If we exhaust the interrupt, exit
00303         if (NIRQ_in)
00304             break;
00305 
00306         // Check that packet length was correct
00307         if (i == -1) {
00308             data = writeCmd(0x0000);
00309             if ( (data&0x8000) ) {
00310                 data = writeCmd(0xB000);
00311                 unsigned char crcofsize = (data&0x00FF);
00312                 if (crcofsize != crc) {
00313                     //It was wrong, start over
00314                     i = -2;
00315                     packet_length = 0;
00316                     crc = 0;
00317                     //temp = queue<unsigned char>();
00318                     resetRX();
00319                 } else {
00320                     crc = crc8(crc, crcofsize);
00321                     i++;
00322                 }
00323             }
00324         }
00325 
00326         //If we exhaust the interrupt, exit
00327         if (NIRQ_in)
00328             break;
00329 
00330         // Grab the packet's data
00331         if (i >= 0 && i < packet_length) {
00332             data = writeCmd(0x0000);
00333             if ( (data&0x8000) ) {
00334                 data = writeCmd(0xB000);
00335  //               #ifdef ROBOT_SECONDARY
00336                 temp = data&0x00FF;
00337  //               #endif
00338                 //temp.push(data&0x00FF);
00339                 crc = crc8(crc, (unsigned char)(data&0x00FF));
00340                 i++;
00341             }
00342         }
00343 
00344         //If we exhaust the interrupt, exit
00345         if (NIRQ_in)
00346             break;
00347 
00348         if (i >= packet_length) {
00349             data = writeCmd(0x0000);
00350             if ( (data&0x8000) ) {
00351                 data = writeCmd(0xB000);
00352                 if ((unsigned char)(data & 0x00FF) == crc) {
00353                     //If the checksum is correct, add our data to the end of the output buffer
00354                     //while (!temp.empty()) {
00355                     //fifo.push(temp);
00356                      //   temp.pop();
00357 //#ifdef ROBOT_SECONDARY
00358                         if (callbackfunc)
00359                             (*callbackfunc)(temp);
00360 
00361                         if (callbackobj && mcallbackfunc)
00362                             (callbackobj->*mcallbackfunc)(temp);
00363 //#endif
00364                    // }
00365                 }
00366 
00367                 // Tell RF Module we are finished, and clean up
00368                 i = -2;
00369                 packet_length = 0;
00370                 crc = 0;
00371                 //temp = queue<unsigned char>();
00372                 resetRX();
00373             }
00374         }
00375     }
00376 
00377 }
00378 
00379 unsigned int RF12B::status() {
00380     return writeCmd(0x0000);
00381 }
00382 
00383 // Tell the RF Module this packet is received and wait for the next */
00384 void RF12B::resetRX() {
00385     writeCmd(0xCA81);
00386     writeCmd(0xCA83);
00387 };
00388 
00389 // Calculate CRC8 */
00390 unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
00391     crc = crc ^ data;
00392     for (int i = 0; i < 8; i++) {
00393         if (crc & 0x01) {
00394             crc = (crc >> 1) ^ 0x8C;
00395         } else {
00396             crc >>= 1;
00397         }
00398     }
00399     return crc;
00400 }