RF12B.cpp

00001 #include "RF12B.h"
00002 
00003 #include "RF_defs.h"
00004 #include "defines.h"
00005 #include <algorithm>
00006 
00007 RF12B::RF12B(PinName _SDI,
00008              PinName _SDO,
00009              PinName _SCK,
00010              PinName _NCS,
00011              PinName _NIRQ,
00012              PinName _TRIG):spi(_SDI, _SDO, _SCK),
00013         NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ), rfled(LED3),trigLED(LED1),TRIG(_TRIG) {
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     /* Dummy code init */
00029     rfCode = 0x00;
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 /* Transmit a 1-byte data packet */
00096 void RF12B::write(unsigned char data) {
00097     write(&data, 1);
00098 }
00099 
00100 void RF12B::write(queue<char> &data, int length) {
00101     char crc = 0;
00102     char length_byte = 0;
00103 
00104     /* -1 means try to transmit everything in the queue */
00105     if (length == -1) {
00106         length = data.size();
00107     }
00108 
00109     /* max length of packet is 255 */
00110     length_byte = min(length, 255);
00111 
00112     /* Transmitter mode */
00113     changeMode(TX);
00114 
00115     writeCmd(0x0000);
00116     send(0xAA); // PREAMBLE
00117     send(0xAA);
00118     send(0xAA);
00119     send(0x2D); // SYNC
00120     send(0xD4);
00121     /* Packet Length */
00122     send(length_byte);
00123     crc = crc8(crc, length_byte);
00124     send(crc);
00125     crc = crc8(crc, crc);
00126     /* Packet Data */
00127     for (char i=0; i<length_byte; i++) {
00128         send(data.front());
00129         crc = crc8(crc, data.front());
00130         data.pop();
00131     }
00132     send(crc);
00133     send(0xAA); // DUMMY BYTES
00134     send(0xAA);
00135     send(0xAA);
00136 
00137     /* Back to receiver mode */
00138     changeMode(RX);
00139     status();
00140 }
00141 
00142 /**********************************************************************
00143  *  PRIVATE FUNCTIONS
00144  *********************************************************************/
00145 
00146 /* Initialises the RF12B module */
00147 void RF12B::init() {
00148     /* writeCmd(0x80E7); //EL,EF,868band,12.0pF
00149      changeMode(RX);
00150      writeCmd(0xA640); //frequency select
00151      writeCmd(0xC647); //4.8kbps
00152      writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
00153      writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
00154      writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
00155      writeCmd(0xCED4); //SYNC=2DD4
00156      writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
00157      writeCmd(0x9850); //!mp,90kHz,MAX OUT
00158      writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT&#65533;CBW0
00159      writeCmd(0xE000); //NOT USED
00160      writeCmd(0xC800); //NOT USED
00161      writeCmd(0xC040); //1.66MHz,2.2V */
00162 
00163     writeCmd(
00164         RFM_CONFIG_EL           |
00165         RFM_CONFIG_EF           |
00166         RFM_CONFIG_BAND_433     //|
00167         //RFM_CONFIG_X_11_0pf // meh, using default
00168     );
00169 
00170     // 2. Power Management Command
00171     // leave everything switched off for now
00172     /*
00173     writeCmd(
00174         RFM_POWER_MANAGEMENT     // switch all off
00175     );
00176     */
00177 
00178     // 3. Frequency Setting Command
00179     writeCmd(
00180         RFM_FREQUENCY            |
00181         RFM_FREQ_433Band(435.7)  //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
00182     );
00183 
00184 
00185     // 4. Data Rate Command
00186     //writeCmd(RFM_DATA_RATE_9600);
00187     writeCmd(RFM_DATA_RATE_57600);
00188 
00189     // 5. Receiver Control Command
00190     writeCmd(
00191         RFM_RX_CONTROL_P20_VDI  |
00192         RFM_RX_CONTROL_VDI_FAST |
00193         //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
00194         RFM_RX_CONTROL_BW_134   |     // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
00195         RFM_RX_CONTROL_GAIN_0   |
00196         RFM_RX_CONTROL_RSSI_103      // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
00197     );
00198 
00199     // 6. Data Filter Command
00200     writeCmd(
00201         RFM_DATA_FILTER_AL      |
00202         RFM_DATA_FILTER_ML      |
00203         RFM_DATA_FILTER_DIG     //|
00204         //RFM_DATA_FILTER_DQD(4)
00205     );
00206 
00207     // 7. FIFO and Reset Mode Command
00208     writeCmd(
00209         RFM_FIFO_IT(8) |
00210         RFM_FIFO_DR    |
00211         0x8 //turn on 16bit sync word
00212     );
00213 
00214     // 8. FIFO Syncword
00215     // Leave as default: 0xD4
00216 
00217     // 9. Receiver FIFO Read
00218     // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
00219     // result = RFM_READ_FIFO();
00220 
00221     // 10. AFC Command
00222     writeCmd(
00223         //RFM_AFC_AUTO_VDI        |  //Note this might be changed to improve range. Refer to datasheet.
00224         RFM_AFC_AUTO_INDEPENDENT    |
00225         RFM_AFC_RANGE_LIMIT_7_8     |
00226         RFM_AFC_EN                  |
00227         RFM_AFC_OE                  |
00228         RFM_AFC_FI
00229     );
00230 
00231     // 11. TX Configuration Control Command
00232     writeCmd(
00233         RFM_TX_CONTROL_MOD_60 |
00234         RFM_TX_CONTROL_POW_0
00235     );
00236 
00237 
00238     // 12. PLL Setting Command
00239     writeCmd(
00240         0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
00241         // I think this will slow down the pll's reaction time. Not sure, check with someone!
00242     );
00243 
00244     changeMode(RX);
00245     resetRX();
00246     status();
00247 }
00248 
00249 /* Write a command to the RF Module */
00250 unsigned int RF12B::writeCmd(unsigned int cmd) {
00251     NCS = 0;
00252     unsigned int recv = spi.write(cmd);
00253     NCS = 1;
00254     return recv;
00255 }
00256 
00257 /* Sends a byte of data across RF */
00258 void RF12B::send(unsigned char data) {
00259     while (NIRQ);
00260     writeCmd(0xB800 + data);
00261 }
00262 
00263 /* Change the mode of the RF module to Transmitting or Receiving */
00264 void RF12B::changeMode(rfmode_t _mode) {
00265     mode = _mode;
00266     if (_mode == TX) {
00267         writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
00268     } else { /* mode == RX */
00269         writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
00270     }
00271 }
00272 
00273 /* Interrupt routine for data reception */
00274 void RF12B::rxISR() {
00275     unsigned int data = 0;
00276     static int i = -2;
00277     static unsigned char packet_length = 0;
00278     static unsigned char crc = 0;
00279     static queue<unsigned char> temp;
00280 
00281     //Loop while interrupt is asserted
00282     while (!NIRQ_in && mode == RX) {
00283 
00284         /* Grab the packet's length byte */
00285         if (i == -2) {
00286             data = writeCmd(0x0000);
00287             if ( (data&0x8000) ) {
00288                 data = writeCmd(0xB000);
00289                 packet_length = (data&0x00FF);
00290                 crc = crc8(crc, packet_length);
00291                 i++;
00292             }
00293         }
00294 
00295         //If we exhaust the interrupt, exit
00296         if (NIRQ_in)
00297             break;
00298 
00299         // Check that packet length was correct
00300         if (i == -1) {
00301             data = writeCmd(0x0000);
00302             if ( (data&0x8000) ) {
00303                 data = writeCmd(0xB000);
00304                 unsigned char crcofsize = (data&0x00FF);
00305                 if (crcofsize != crc) {
00306                     //It was wrong, start over
00307                     i = -2;
00308                     packet_length = 0;
00309                     crc = 0;
00310                     temp = queue<unsigned char>();
00311                     resetRX();
00312                 } else {
00313                     crc = crc8(crc, crcofsize);
00314                     i++;
00315                 }
00316             }
00317         }
00318 
00319         //If we exhaust the interrupt, exit
00320         if (NIRQ_in)
00321             break;
00322 
00323         /* Grab the packet's data */
00324         if (i >= 0 && i < packet_length) {
00325             data = writeCmd(0x0000);
00326             if ( (data&0x8000) ) {
00327                 data = writeCmd(0xB000);
00328                 temp.push(data&0x00FF);
00329                 crc = crc8(crc, (unsigned char)(data&0x00FF));
00330                 i++;
00331             }
00332         }
00333 
00334         //If we exhaust the interrupt, exit
00335         if (NIRQ_in)
00336             break;
00337 
00338         if (i >= packet_length) {
00339             data = writeCmd(0x0000);
00340             if ( (data&0x8000) ) {
00341                 data = writeCmd(0xB000);
00342                 if ((unsigned char)(data & 0x00FF) == crc) {
00343                     //If the checksum is correct, add our data to the end of the output buffer
00344                     while (!temp.empty()) {
00345                         fifo.push(temp.front());
00346                         temp.pop();
00347 
00348                         if (read() == rfCode) {
00349                             TRIG = 1;
00350                             wait_us(10);
00351                             TRIG = 0;
00352                             trigLED = !trigLED;
00353                         }
00354                     }
00355                 }
00356 
00357                 /* Tell RF Module we are finished, and clean up */
00358                 i = -2;
00359                 packet_length = 0;
00360                 crc = 0;
00361                 temp = queue<unsigned char>();
00362                 resetRX();
00363             }
00364         }
00365     }
00366 }
00367 
00368 unsigned int RF12B::status() {
00369     return writeCmd(0x0000);
00370 }
00371 
00372 /* Tell the RF Module this packet is received and wait for the next */
00373 void RF12B::resetRX() {
00374     writeCmd(0xCA81);
00375     writeCmd(0xCA83);
00376 };
00377 
00378 /* Calculate CRC8 */
00379 unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
00380     crc = crc ^ data;
00381     for (int i = 0; i < 8; i++) {
00382         if (crc & 0x01) {
00383             crc = (crc >> 1) ^ 0x8C;
00384         } else {
00385             crc >>= 1;
00386         }
00387     }
00388     return crc;
00389 }
00390 
00391 /* RF code set */
00392 void RF12B::setCode(unsigned char code) {
00393     rfCode = code;
00394 }