RF12B.cpp

00001 #include "RF12B.h"
00002 
00003 #include "RF_defs.h"
00004 #include <algorithm>
00005 
00006 //#include "globals.h"
00007 
00008 DigitalOut DBG2(LED2);
00009 DigitalOut DBG3(LED3);
00010 DigitalOut DBG4(LED4);
00011 
00012 RF12B::RF12B(PinName _SDI,
00013              PinName _SDO,
00014              PinName _SCK,
00015              PinName _NCS,
00016              PinName _NIRQ):spi(_SDI, _SDO, _SCK),
00017         NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ){// rfled(LED3) {
00018 
00019     /* SPI frequency, word lenght, polarity and phase */
00020     spi.format(16,0);
00021     spi.frequency(2000000);
00022 
00023     /* Set ~CS high */
00024     NCS = 1;
00025 
00026     /* Initialise RF Module */
00027     init();
00028 
00029     /* Setup interrupt to happen on falling edge of NIRQ */
00030     NIRQ.fall(this, &RF12B::rxISR);
00031     
00032 
00033 }
00034 
00035 /* Returns the packet length if data is available in the receive buffer, 0 otherwise*/
00036 unsigned int RF12B::available() {
00037     return fifo.size();
00038 }
00039 
00040 /* Reads a packet of data, with length "size" Returns false if read failed. TODO: make a metafifo to isolate packets*/
00041 bool RF12B::read(unsigned char* data, unsigned int size) {
00042     if (fifo.size() == 0) {
00043         return false;
00044     } else {
00045         unsigned int i = 0;
00046         while (fifo.size() > 0 && i < size) {
00047             data[i++] = fifo.front();
00048             fifo.pop();
00049         }
00050         return true;
00051     }
00052 }
00053 
00054 /* Reads a byte of data from the receive buffer */
00055 unsigned char RF12B::read() {
00056     if (available()) {
00057         unsigned char data = fifo.front();
00058         fifo.pop();
00059         return data;
00060     } else {
00061         return 0xFF; // Error val although could also be data...
00062     }
00063 }
00064 
00065 /* Sends a packet of data to the RF module for transmission TODO: Make asych*/
00066 void RF12B::write(unsigned char *data, unsigned char length) {
00067     unsigned char crc = 0;
00068        
00069     /* Transmitter mode */
00070     changeMode(TX);
00071 
00072     writeCmd(0x0000);
00073     send(0xAA); // PREAMBLE
00074     send(0xAA);
00075     send(0xAA);
00076     send(0x2D); // SYNC
00077     send(0xD4);
00078     /* Packet Length */
00079     send(length);
00080     crc = crc8(crc, length);
00081     send(crc);
00082     crc = crc8(crc, crc);
00083     /* Packet Data */
00084     for (unsigned char i=0; i<length; i++) {
00085         send(data[i]);
00086         crc = crc8(crc, data[i]);
00087     }
00088     send(crc);
00089     send(0xAA); // DUMMY BYTES
00090     send(0xAA);
00091     send(0xAA);
00092 
00093     /* Back to receiver mode */
00094     changeMode(RX);
00095     status();
00096     
00097 
00098 }
00099 
00100 /* Transmit a 1-byte data packet */
00101 void RF12B::write(unsigned char data) {
00102     write(&data, 1);
00103 }
00104 
00105 void RF12B::write(queue<char> &data, int length) {
00106     char crc = 0;
00107     char length_byte = 0;
00108     
00109     /* -1 means try to transmit everything in the queue */
00110     if(length == -1) {
00111         length = data.size();
00112     }
00113     
00114     /* max length of packet is 255 */
00115     length_byte = min(length, 255);
00116     
00117     /* Transmitter mode */
00118     changeMode(TX);
00119 
00120     writeCmd(0x0000);
00121     send(0xAA); // PREAMBLE
00122     send(0xAA);
00123     send(0xAA);
00124     send(0x2D); // SYNC
00125     send(0xD4);
00126     /* Packet Length */
00127     send(length_byte);
00128     crc = crc8(crc, length_byte);
00129     send(crc);
00130     crc = crc8(crc, crc);
00131     /* Packet Data */
00132     for (char i=0; i<length_byte; i++) {
00133         send(data.front());
00134         crc = crc8(crc, data.front());
00135         data.pop();
00136     }
00137     send(crc);
00138     send(0xAA); // DUMMY BYTES
00139     send(0xAA);
00140     send(0xAA);
00141 
00142     /* Back to receiver mode */
00143     changeMode(RX);
00144     status();
00145 }
00146 
00147 /**********************************************************************
00148  *  PRIVATE FUNCTIONS
00149  *********************************************************************/
00150 
00151 /* Initialises the RF12B module */
00152 void RF12B::init() {
00153     /* writeCmd(0x80E7); //EL,EF,868band,12.0pF
00154      changeMode(RX);
00155      writeCmd(0xA640); //frequency select
00156      writeCmd(0xC647); //4.8kbps
00157      writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
00158      writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
00159      writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
00160      writeCmd(0xCED4); //SYNC=2DD4
00161      writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
00162      writeCmd(0x9850); //!mp,90kHz,MAX OUT
00163      writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT&#65533;CBW0
00164      writeCmd(0xE000); //NOT USED
00165      writeCmd(0xC800); //NOT USED
00166      writeCmd(0xC040); //1.66MHz,2.2V */
00167 
00168     writeCmd(
00169         RFM_CONFIG_EL           |
00170         RFM_CONFIG_EF           |
00171         RFM_CONFIG_BAND_433     //|
00172         //RFM_CONFIG_X_11_0pf // meh, using default
00173     );
00174 
00175     // 2. Power Management Command
00176     // leave everything switched off for now
00177     /*
00178     writeCmd(
00179         RFM_POWER_MANAGEMENT     // switch all off
00180     );
00181     */
00182 
00183     // 3. Frequency Setting Command
00184     writeCmd(
00185         RFM_FREQUENCY            |
00186         RFM_FREQ_433Band(435.7)  //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
00187     );
00188 
00189 
00190     // 4. Data Rate Command
00191     writeCmd(RFM_DATA_RATE_9600);
00192 
00193 
00194     // 5. Receiver Control Command
00195     writeCmd(
00196         RFM_RX_CONTROL_P20_VDI  |
00197         RFM_RX_CONTROL_VDI_FAST |
00198         //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
00199         RFM_RX_CONTROL_BW_134   |     // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
00200         RFM_RX_CONTROL_GAIN_0   |
00201         RFM_RX_CONTROL_RSSI_103      // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
00202     );
00203 
00204     // 6. Data Filter Command
00205     writeCmd(
00206         RFM_DATA_FILTER_AL      |
00207         RFM_DATA_FILTER_ML      |
00208         RFM_DATA_FILTER_DIG     //|
00209         //RFM_DATA_FILTER_DQD(4)
00210     );
00211 
00212     // 7. FIFO and Reset Mode Command
00213     writeCmd(
00214         RFM_FIFO_IT(8) |
00215         RFM_FIFO_DR    |
00216         0x8 //turn on 16bit sync word
00217     );
00218 
00219     // 8. FIFO Syncword
00220     // Leave as default: 0xD4
00221 
00222     // 9. Receiver FIFO Read
00223     // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
00224     // result = RFM_READ_FIFO();
00225 
00226     // 10. AFC Command
00227     writeCmd(
00228         //RFM_AFC_AUTO_VDI        |  //Note this might be changed to improve range. Refer to datasheet.
00229         RFM_AFC_AUTO_INDEPENDENT    |
00230         RFM_AFC_RANGE_LIMIT_7_8     |
00231         RFM_AFC_EN                  |
00232         RFM_AFC_OE                  |
00233         RFM_AFC_FI
00234     );
00235 
00236     // 11. TX Configuration Control Command
00237     writeCmd(
00238         RFM_TX_CONTROL_MOD_60 |
00239         RFM_TX_CONTROL_POW_0
00240     );
00241 
00242 
00243     // 12. PLL Setting Command
00244     writeCmd(
00245         0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
00246         // I think this will slow down the pll's reaction time. Not sure, check with someone!
00247     );
00248 
00249     changeMode(RX);
00250     resetRX();
00251     status();
00252 }
00253 
00254 /* Write a command to the RF Module */
00255 unsigned int RF12B::writeCmd(unsigned int cmd) {
00256     NCS = 0;
00257     unsigned int recv = spi.write(cmd);
00258     NCS = 1;
00259     return recv;
00260 }
00261 
00262 /* Sends a byte of data across RF */
00263 void RF12B::send(unsigned char data) {
00264     while (NIRQ);
00265     writeCmd(0xB800 + data);
00266 }
00267 
00268 /* Change the mode of the RF module to Transmitting or Receiving */
00269 void RF12B::changeMode(rfmode_t _mode) {
00270     mode = _mode;
00271     if (_mode == TX) {
00272         writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
00273     } else { /* mode == RX */
00274         writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
00275     }
00276 }
00277 
00278 /* Interrupt routine for data reception */
00279 void RF12B::rxISR() {
00280     
00281     static int cnt = 0;
00282     //printf("%d hits\r\n", cnt);
00283     cnt++;
00284     
00285     DBG2 = !(cnt%3);
00286     DBG3 = !((cnt+1)%3);
00287     DBG4 = !((cnt+2)%3);
00288     
00289 
00290     unsigned int data = 0;
00291     static int i = -2;
00292     static unsigned char packet_length = 0;
00293     static unsigned char crc = 0;
00294     static queue<unsigned char> temp;
00295     
00296     
00297     //Loop while interrupt is asserted
00298     while (!NIRQ_in && mode == RX) {
00299         
00300         
00301         // Grab the packet's length byte
00302         if (i == -2) {
00303             data = writeCmd(0x0000);
00304             if ( (data&0x8000) ) {
00305                 data = writeCmd(0xB000);
00306                 packet_length = (data&0x00FF);
00307                 crc = crc8(crc, packet_length);
00308                 i++;
00309             }
00310         }
00311 
00312         //If we exhaust the interrupt, exit
00313         if (NIRQ_in)
00314             break;
00315 
00316         // Check that packet length was correct
00317         if (i == -1) {
00318             data = writeCmd(0x0000);
00319             if ( (data&0x8000) ) {
00320                 data = writeCmd(0xB000);
00321                 unsigned char crcofsize = (data&0x00FF);
00322                 if (crcofsize != crc) {
00323                     //It was wrong, start over
00324                     i = -2;
00325                     packet_length = 0;
00326                     crc = 0;
00327                     temp = queue<unsigned char>();
00328                     resetRX();
00329                 } else {
00330                     crc = crc8(crc, crcofsize);
00331                     i++;
00332                 }
00333             }
00334         }
00335 
00336         //If we exhaust the interrupt, exit
00337         if (NIRQ_in)
00338             break;
00339 
00340         // Grab the packet's data 
00341         if (i >= 0 && i < packet_length) {
00342             data = writeCmd(0x0000);
00343             if ( (data&0x8000) ) {
00344                 data = writeCmd(0xB000);
00345                 temp.push(data&0x00FF);
00346                 crc = crc8(crc, (unsigned char)(data&0x00FF));
00347                 i++;
00348             }
00349         }
00350 
00351         //If we exhaust the interrupt, exit
00352         if (NIRQ_in)
00353             break;
00354 
00355         if (i >= packet_length) {
00356             data = writeCmd(0x0000);
00357             if ( (data&0x8000) ) {
00358                 data = writeCmd(0xB000);
00359                 if ((unsigned char)(data & 0x00FF) == crc) {
00360                     //If the checksum is correct, add our data to the end of the output buffer
00361                     while (!temp.empty()) {
00362                         fifo.push(temp.front());
00363                         temp.pop();
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 }