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 /* Returns the packet length if data is available in the receive buffer, 0 otherwise*/
00034 unsigned int RF12B::available() {
00035     return fifo.size();
00036 }
00037 
00038 /* Reads a packet of data, with length "size" Returns false if read failed. TODO: make a metafifo to isolate packets*/
00039 bool RF12B::read(unsigned char* data, unsigned int size) {
00040     if (fifo.size() == 0) {
00041         return false;
00042     } else {
00043         unsigned int i = 0;
00044         while (fifo.size() > 0 && i < size) {
00045             data[i++] = fifo.front();
00046             fifo.pop();
00047         }
00048         return true;
00049     }
00050 }
00051 
00052 /* Reads a byte of data from the receive buffer */
00053 unsigned char RF12B::read() {
00054     if (available()) {
00055         unsigned char data = fifo.front();
00056         fifo.pop();
00057         return data;
00058     } else {
00059         return 0xFF; // Error val although could also be data...
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 
00191 
00192     // 5. Receiver Control Command
00193     writeCmd(
00194         RFM_RX_CONTROL_P20_VDI  |
00195         RFM_RX_CONTROL_VDI_FAST |
00196         //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
00197         RFM_RX_CONTROL_BW_134   |     // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
00198         RFM_RX_CONTROL_GAIN_0   |
00199         RFM_RX_CONTROL_RSSI_103      // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
00200     );
00201 
00202     // 6. Data Filter Command
00203     writeCmd(
00204         RFM_DATA_FILTER_AL      |
00205         RFM_DATA_FILTER_ML      |
00206         RFM_DATA_FILTER_DIG     //|
00207         //RFM_DATA_FILTER_DQD(4)
00208     );
00209 
00210     // 7. FIFO and Reset Mode Command
00211     writeCmd(
00212         RFM_FIFO_IT(8) |
00213         RFM_FIFO_DR    |
00214         0x8 //turn on 16bit sync word
00215     );
00216 
00217     // 8. FIFO Syncword
00218     // Leave as default: 0xD4
00219 
00220     // 9. Receiver FIFO Read
00221     // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
00222     // result = RFM_READ_FIFO();
00223 
00224     // 10. AFC Command
00225     writeCmd(
00226         //RFM_AFC_AUTO_VDI        |  //Note this might be changed to improve range. Refer to datasheet.
00227         RFM_AFC_AUTO_INDEPENDENT    |
00228         RFM_AFC_RANGE_LIMIT_7_8     |
00229         RFM_AFC_EN                  |
00230         RFM_AFC_OE                  |
00231         RFM_AFC_FI
00232     );
00233 
00234     // 11. TX Configuration Control Command
00235     writeCmd(
00236         RFM_TX_CONTROL_MOD_60 |
00237         RFM_TX_CONTROL_POW_0
00238     );
00239 
00240 
00241     // 12. PLL Setting Command
00242     writeCmd(
00243         0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
00244         // I think this will slow down the pll's reaction time. Not sure, check with someone!
00245     );
00246 
00247     changeMode(RX);
00248     resetRX();
00249     status();
00250 }
00251 
00252 /* Write a command to the RF Module */
00253 unsigned int RF12B::writeCmd(unsigned int cmd) {
00254     NCS = 0;
00255     unsigned int recv = spi.write(cmd);
00256     NCS = 1;
00257     return recv;
00258 }
00259 
00260 /* Sends a byte of data across RF */
00261 void RF12B::send(unsigned char data) {
00262     while (NIRQ);
00263     writeCmd(0xB800 + data);
00264 }
00265 
00266 /* Change the mode of the RF module to Transmitting or Receiving */
00267 void RF12B::changeMode(rfmode_t _mode) {
00268     mode = _mode;
00269     if (_mode == TX) {
00270         writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
00271     } else { /* mode == RX */
00272         writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
00273     }
00274 }
00275 
00276 /* Interrupt routine for data reception */
00277 void RF12B::rxISR() {
00278     
00279     //static int cnt = 0;
00280     //printf("%d hits\r\n", cnt);
00281     //cnt++;
00282     
00283     //DBG2 = !(cnt%3);
00284     //DBG3 = !((cnt+1)%3);
00285     //DBG4 = !((cnt+2)%3);
00286 
00287     unsigned int data = 0;
00288     static int i = -2;
00289     static unsigned char packet_length = 0;
00290     static unsigned char crc = 0;
00291 
00292     //Loop while interrupt is asserted
00293     while (!NIRQ_in && mode == RX) {
00294         
00295         // Grab the packet's length byte
00296         if (i == -2) {
00297             data = writeCmd(0x0000);
00298             if ( (data&0x8000) ) {
00299                 data = writeCmd(0xB000);
00300                 packet_length = (data&0x00FF);
00301                 crc = crc8(crc, packet_length);
00302                 i++;
00303             }
00304         }
00305 
00306         //If we exhaust the interrupt, exit
00307         if (NIRQ_in)
00308             break;
00309 
00310         // Check that packet length was correct
00311         if (i == -1) {
00312             data = writeCmd(0x0000);
00313             if ( (data&0x8000) ) {
00314                 data = writeCmd(0xB000);
00315                 unsigned char crcofsize = (data&0x00FF);
00316                 if (crcofsize != crc) {
00317                     //It was wrong, start over
00318                     i = -2;
00319                     packet_length = 0;
00320                     crc = 0;
00321                     //temp = queue<unsigned char>();
00322                     resetRX();
00323                 } else {
00324                     crc = crc8(crc, crcofsize);
00325                     i++;
00326                 }
00327             }
00328         }
00329 
00330         //If we exhaust the interrupt, exit
00331         if (NIRQ_in)
00332             break;
00333 
00334         // Grab the packet's data 
00335         if (i >= 0 && i < packet_length) {
00336             data = writeCmd(0x0000);
00337             if ( (data&0x8000) ) {
00338                 data = writeCmd(0xB000);
00339                 //temp.push(data&0x00FF);
00340                 crc = crc8(crc, (unsigned char)(data&0x00FF));
00341                 i++;
00342             }
00343         }
00344 
00345         //If we exhaust the interrupt, exit
00346         if (NIRQ_in)
00347             break;
00348 
00349         if (i >= packet_length) {
00350             data = writeCmd(0x0000);
00351             if ( (data&0x8000) ) {
00352                 data = writeCmd(0xB000);
00353                 if ((unsigned char)(data & 0x00FF) == crc) {
00354                     //If the checksum is correct, add our data to the end of the output buffer
00355                     //while (!temp.empty()) {
00356                     //    fifo.push(temp.front());
00357                     //    temp.pop();
00358                     //}
00359                 }
00360 
00361                 // Tell RF Module we are finished, and clean up
00362                 i = -2;
00363                 packet_length = 0;
00364                 crc = 0;
00365                 //temp = queue<unsigned char>();
00366                 resetRX();
00367             }
00368         }
00369     }
00370 }
00371 
00372 unsigned int RF12B::status() {
00373     return writeCmd(0x0000);
00374 }
00375 
00376 /* Tell the RF Module this packet is received and wait for the next */
00377 void RF12B::resetRX() {
00378     writeCmd(0xCA81);
00379     writeCmd(0xCA83);
00380 };
00381 
00382 /* Calculate CRC8 */
00383 unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
00384     crc = crc ^ data;
00385     for (int i = 0; i < 8; i++) {
00386         if (crc & 0x01) {
00387             crc = (crc >> 1) ^ 0x8C;
00388         } else {
00389             crc >>= 1;
00390         }
00391     }
00392     return crc;
00393 }