Shuto Naruse / Eurobot_2012_shared

Eurobot_shared pubulished from Eurobot Primary

Kalman/Sonar/RF12B/RF12B.cpp@0:434fd09723be, 2012-08-07 (annotated)

Committer:
narshu
Date:
Tue Aug 07 10:25:53 2012 +0000
Revision:
0:434fd09723be
[mbed] converted /Eurobot_2012_Primary/Eurobot_shared

Who changed what in which revision?

UserRevisionLine numberNew contents of line
narshu 0:434fd09723be 1 #include "RF12B.h"
narshu 0:434fd09723be 2
narshu 0:434fd09723be 3 #include "RF_defs.h"
narshu 0:434fd09723be 4 #include <algorithm>
narshu 0:434fd09723be 5 #include "system.h"
narshu 0:434fd09723be 6 #include "globals.h"
narshu 0:434fd09723be 7
narshu 0:434fd09723be 8
narshu 0:434fd09723be 9 RF12B::RF12B(PinName _SDI,
narshu 0:434fd09723be 10 PinName _SDO,
narshu 0:434fd09723be 11 PinName _SCK,
narshu 0:434fd09723be 12 PinName _NCS,
narshu 0:434fd09723be 13 PinName _NIRQ):spi(_SDI, _SDO, _SCK),
narshu 0:434fd09723be 14 NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ) {// rfled(LED3) {
narshu 0:434fd09723be 15
narshu 0:434fd09723be 16 // SPI frequency, word lenght, polarity and phase */
narshu 0:434fd09723be 17 spi.format(16,0);
narshu 0:434fd09723be 18 spi.frequency(2000000);
narshu 0:434fd09723be 19
narshu 0:434fd09723be 20 // Set ~CS high
narshu 0:434fd09723be 21 NCS = 1;
narshu 0:434fd09723be 22
narshu 0:434fd09723be 23 // Initialise RF Module
narshu 0:434fd09723be 24 init();
narshu 0:434fd09723be 25
narshu 0:434fd09723be 26 // Setup interrupt to happen on falling edge of NIRQ
narshu 0:434fd09723be 27 NIRQ.fall(this, &RF12B::rxISR);
narshu 0:434fd09723be 28 }
narshu 0:434fd09723be 29
narshu 0:434fd09723be 30 // Returns the packet length if data is available in the receive buffer, 0 otherwise
narshu 0:434fd09723be 31 //unsigned int RF12B::available() {
narshu 0:434fd09723be 32 // return fifo.size();
narshu 0:434fd09723be 33 //}
narshu 0:434fd09723be 34
narshu 0:434fd09723be 35 // Reads a packet of data, with length "size" Returns false if read failed. TODO: make a metafifo to isolate packets
narshu 0:434fd09723be 36 /*bool RF12B::read(unsigned char* data, unsigned int size) {
narshu 0:434fd09723be 37 if (fifo.size() == 0) {
narshu 0:434fd09723be 38 return false;
narshu 0:434fd09723be 39 } else {
narshu 0:434fd09723be 40 unsigned int i = 0;
narshu 0:434fd09723be 41 while (fifo.size() > 0 && i < size) {
narshu 0:434fd09723be 42 data[i++] = fifo.front();
narshu 0:434fd09723be 43 fifo.pop();
narshu 0:434fd09723be 44 }
narshu 0:434fd09723be 45 return true;
narshu 0:434fd09723be 46 }
narshu 0:434fd09723be 47 }
narshu 0:434fd09723be 48 */
narshu 0:434fd09723be 49
narshu 0:434fd09723be 50 // Reads a byte of data from the receive buffer
narshu 0:434fd09723be 51 /*
narshu 0:434fd09723be 52 unsigned char RF12B::read() {
narshu 0:434fd09723be 53 if (available()) {
narshu 0:434fd09723be 54 unsigned char data = fifo.front();
narshu 0:434fd09723be 55 fifo.pop();
narshu 0:434fd09723be 56 return data;
narshu 0:434fd09723be 57 } else {
narshu 0:434fd09723be 58 return 0xFF; // Error val although could also be data...
narshu 0:434fd09723be 59 }
narshu 0:434fd09723be 60 }
narshu 0:434fd09723be 61 */
narshu 0:434fd09723be 62
narshu 0:434fd09723be 63 // Sends a packet of data to the RF module for transmission TODO: Make asych
narshu 0:434fd09723be 64 void RF12B::write(unsigned char *data, unsigned char length) {
narshu 0:434fd09723be 65 unsigned char crc = 0;
narshu 0:434fd09723be 66
narshu 0:434fd09723be 67 // Transmitter mode
narshu 0:434fd09723be 68 changeMode(TX);
narshu 0:434fd09723be 69
narshu 0:434fd09723be 70 writeCmd(0x0000);
narshu 0:434fd09723be 71 send(0xAA); // PREAMBLE
narshu 0:434fd09723be 72 send(0xAA);
narshu 0:434fd09723be 73 send(0xAA);
narshu 0:434fd09723be 74 send(0x2D); // SYNC
narshu 0:434fd09723be 75 send(0xD4);
narshu 0:434fd09723be 76 // Packet Length
narshu 0:434fd09723be 77 send(length);
narshu 0:434fd09723be 78 crc = crc8(crc, length);
narshu 0:434fd09723be 79 send(crc);
narshu 0:434fd09723be 80 crc = crc8(crc, crc);
narshu 0:434fd09723be 81 // Packet Data
narshu 0:434fd09723be 82 for (unsigned char i=0; i<length; i++) {
narshu 0:434fd09723be 83 send(data[i]);
narshu 0:434fd09723be 84 crc = crc8(crc, data[i]);
narshu 0:434fd09723be 85 }
narshu 0:434fd09723be 86 send(crc);
narshu 0:434fd09723be 87 send(0xAA); // DUMMY BYTES
narshu 0:434fd09723be 88 send(0xAA);
narshu 0:434fd09723be 89 send(0xAA);
narshu 0:434fd09723be 90
narshu 0:434fd09723be 91 // Back to receiver mode
narshu 0:434fd09723be 92 changeMode(RX);
narshu 0:434fd09723be 93 status();
narshu 0:434fd09723be 94
narshu 0:434fd09723be 95
narshu 0:434fd09723be 96 }
narshu 0:434fd09723be 97
narshu 0:434fd09723be 98 // Transmit a 1-byte data packet
narshu 0:434fd09723be 99 void RF12B::write(unsigned char data) {
narshu 0:434fd09723be 100 write(&data, 1);
narshu 0:434fd09723be 101 }
narshu 0:434fd09723be 102 /*
narshu 0:434fd09723be 103 void RF12B::write(queue<char> &data, int length) {
narshu 0:434fd09723be 104 char crc = 0;
narshu 0:434fd09723be 105 char length_byte = 0;
narshu 0:434fd09723be 106
narshu 0:434fd09723be 107 // -1 means try to transmit everything in the queue
narshu 0:434fd09723be 108 if (length == -1) {
narshu 0:434fd09723be 109 length = data.size();
narshu 0:434fd09723be 110 }
narshu 0:434fd09723be 111
narshu 0:434fd09723be 112 // max length of packet is 255
narshu 0:434fd09723be 113 length_byte = min(length, 255);
narshu 0:434fd09723be 114
narshu 0:434fd09723be 115 // Transmitter mode
narshu 0:434fd09723be 116 changeMode(TX);
narshu 0:434fd09723be 117
narshu 0:434fd09723be 118 writeCmd(0x0000);
narshu 0:434fd09723be 119 send(0xAA); // PREAMBLE
narshu 0:434fd09723be 120 send(0xAA);
narshu 0:434fd09723be 121 send(0xAA);
narshu 0:434fd09723be 122 send(0x2D); // SYNC
narshu 0:434fd09723be 123 send(0xD4);
narshu 0:434fd09723be 124 // Packet Length
narshu 0:434fd09723be 125 send(length_byte);
narshu 0:434fd09723be 126 crc = crc8(crc, length_byte);
narshu 0:434fd09723be 127 send(crc);
narshu 0:434fd09723be 128 crc = crc8(crc, crc);
narshu 0:434fd09723be 129 // Packet Data
narshu 0:434fd09723be 130 for (char i=0; i<length_byte; i++) {
narshu 0:434fd09723be 131 send(data.front());
narshu 0:434fd09723be 132 crc = crc8(crc, data.front());
narshu 0:434fd09723be 133 data.pop();
narshu 0:434fd09723be 134 }
narshu 0:434fd09723be 135 send(crc);
narshu 0:434fd09723be 136 send(0xAA); // DUMMY BYTES
narshu 0:434fd09723be 137 send(0xAA);
narshu 0:434fd09723be 138 send(0xAA);
narshu 0:434fd09723be 139
narshu 0:434fd09723be 140 // Back to receiver mode
narshu 0:434fd09723be 141 changeMode(RX);
narshu 0:434fd09723be 142 status();
narshu 0:434fd09723be 143 }
narshu 0:434fd09723be 144 */
narshu 0:434fd09723be 145 /**********************************************************************
narshu 0:434fd09723be 146 * PRIVATE FUNCTIONS
narshu 0:434fd09723be 147 *********************************************************************/
narshu 0:434fd09723be 148
narshu 0:434fd09723be 149 // Initialises the RF12B module
narshu 0:434fd09723be 150 void RF12B::init() {
narshu 0:434fd09723be 151 // writeCmd(0x80E7); //EL,EF,868band,12.0pF
narshu 0:434fd09723be 152 changeMode(RX);
narshu 0:434fd09723be 153 writeCmd(0xA640); //frequency select
narshu 0:434fd09723be 154 writeCmd(0xC647); //4.8kbps
narshu 0:434fd09723be 155 writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
narshu 0:434fd09723be 156 writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
narshu 0:434fd09723be 157 writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
narshu 0:434fd09723be 158 writeCmd(0xCED4); //SYNC=2DD4
narshu 0:434fd09723be 159 writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
narshu 0:434fd09723be 160 writeCmd(0x9850); //!mp,90kHz,MAX OUT
narshu 0:434fd09723be 161 writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT&#65533;CBW0
narshu 0:434fd09723be 162 writeCmd(0xE000); //NOT USED
narshu 0:434fd09723be 163 writeCmd(0xC800); //NOT USED
narshu 0:434fd09723be 164 writeCmd(0xC040); //1.66MHz,2.2V
narshu 0:434fd09723be 165
narshu 0:434fd09723be 166 writeCmd(
narshu 0:434fd09723be 167 RFM_CONFIG_EL |
narshu 0:434fd09723be 168 RFM_CONFIG_EF |
narshu 0:434fd09723be 169 RFM_CONFIG_BAND_433 //|
narshu 0:434fd09723be 170 //RFM_CONFIG_X_11_0pf // meh, using default
narshu 0:434fd09723be 171 );
narshu 0:434fd09723be 172
narshu 0:434fd09723be 173 // 2. Power Management Command
narshu 0:434fd09723be 174 // leave everything switched off for now
narshu 0:434fd09723be 175 /*
narshu 0:434fd09723be 176 writeCmd(
narshu 0:434fd09723be 177 RFM_POWER_MANAGEMENT // switch all off
narshu 0:434fd09723be 178 );
narshu 0:434fd09723be 179 */
narshu 0:434fd09723be 180
narshu 0:434fd09723be 181 // 3. Frequency Setting Command
narshu 0:434fd09723be 182 writeCmd(
narshu 0:434fd09723be 183 RFM_FREQUENCY |
narshu 0:434fd09723be 184 RFM_FREQ_433Band(435.7) //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
narshu 0:434fd09723be 185 );
narshu 0:434fd09723be 186
narshu 0:434fd09723be 187
narshu 0:434fd09723be 188 // 4. Data Rate Command
narshu 0:434fd09723be 189 //writeCmd(RFM_DATA_RATE_9600);
narshu 0:434fd09723be 190 writeCmd(RFM_DATA_RATE_57600);
narshu 0:434fd09723be 191
narshu 0:434fd09723be 192
narshu 0:434fd09723be 193 // 5. Receiver Control Command
narshu 0:434fd09723be 194 writeCmd(
narshu 0:434fd09723be 195 RFM_RX_CONTROL_P20_VDI |
narshu 0:434fd09723be 196 RFM_RX_CONTROL_VDI_FAST |
narshu 0:434fd09723be 197 //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
narshu 0:434fd09723be 198 RFM_RX_CONTROL_BW_134 | // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
narshu 0:434fd09723be 199 RFM_RX_CONTROL_GAIN_0 |
narshu 0:434fd09723be 200 RFM_RX_CONTROL_RSSI_103 // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
narshu 0:434fd09723be 201 );
narshu 0:434fd09723be 202
narshu 0:434fd09723be 203 // 6. Data Filter Command
narshu 0:434fd09723be 204 writeCmd(
narshu 0:434fd09723be 205 RFM_DATA_FILTER_AL |
narshu 0:434fd09723be 206 RFM_DATA_FILTER_ML |
narshu 0:434fd09723be 207 RFM_DATA_FILTER_DIG //|
narshu 0:434fd09723be 208 //RFM_DATA_FILTER_DQD(4)
narshu 0:434fd09723be 209 );
narshu 0:434fd09723be 210
narshu 0:434fd09723be 211 // 7. FIFO and Reset Mode Command
narshu 0:434fd09723be 212 writeCmd(
narshu 0:434fd09723be 213 RFM_FIFO_IT(8) |
narshu 0:434fd09723be 214 RFM_FIFO_DR |
narshu 0:434fd09723be 215 0x8 //turn on 16bit sync word
narshu 0:434fd09723be 216 );
narshu 0:434fd09723be 217
narshu 0:434fd09723be 218 // 8. FIFO Syncword
narshu 0:434fd09723be 219 // Leave as default: 0xD4
narshu 0:434fd09723be 220
narshu 0:434fd09723be 221 // 9. Receiver FIFO Read
narshu 0:434fd09723be 222 // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
narshu 0:434fd09723be 223 // result = RFM_READ_FIFO();
narshu 0:434fd09723be 224
narshu 0:434fd09723be 225 // 10. AFC Command
narshu 0:434fd09723be 226 writeCmd(
narshu 0:434fd09723be 227 //RFM_AFC_AUTO_VDI | //Note this might be changed to improve range. Refer to datasheet.
narshu 0:434fd09723be 228 RFM_AFC_AUTO_INDEPENDENT |
narshu 0:434fd09723be 229 RFM_AFC_RANGE_LIMIT_7_8 |
narshu 0:434fd09723be 230 RFM_AFC_EN |
narshu 0:434fd09723be 231 RFM_AFC_OE |
narshu 0:434fd09723be 232 RFM_AFC_FI
narshu 0:434fd09723be 233 );
narshu 0:434fd09723be 234
narshu 0:434fd09723be 235 // 11. TX Configuration Control Command
narshu 0:434fd09723be 236 writeCmd(
narshu 0:434fd09723be 237 RFM_TX_CONTROL_MOD_60 |
narshu 0:434fd09723be 238 RFM_TX_CONTROL_POW_0
narshu 0:434fd09723be 239 );
narshu 0:434fd09723be 240
narshu 0:434fd09723be 241
narshu 0:434fd09723be 242 // 12. PLL Setting Command
narshu 0:434fd09723be 243 writeCmd(
narshu 0:434fd09723be 244 0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
narshu 0:434fd09723be 245 // I think this will slow down the pll's reaction time. Not sure, check with someone!
narshu 0:434fd09723be 246 );
narshu 0:434fd09723be 247
narshu 0:434fd09723be 248 changeMode(RX);
narshu 0:434fd09723be 249 resetRX();
narshu 0:434fd09723be 250 status();
narshu 0:434fd09723be 251 }
narshu 0:434fd09723be 252
narshu 0:434fd09723be 253 /* Write a command to the RF Module */
narshu 0:434fd09723be 254 unsigned int RF12B::writeCmd(unsigned int cmd) {
narshu 0:434fd09723be 255 NCS = 0;
narshu 0:434fd09723be 256 unsigned int recv = spi.write(cmd);
narshu 0:434fd09723be 257 NCS = 1;
narshu 0:434fd09723be 258 return recv;
narshu 0:434fd09723be 259 }
narshu 0:434fd09723be 260
narshu 0:434fd09723be 261 /* Sends a byte of data across RF */
narshu 0:434fd09723be 262 void RF12B::send(unsigned char data) {
narshu 0:434fd09723be 263 while (NIRQ);
narshu 0:434fd09723be 264 writeCmd(0xB800 + data);
narshu 0:434fd09723be 265 }
narshu 0:434fd09723be 266
narshu 0:434fd09723be 267 /* Change the mode of the RF module to Transmitting or Receiving */
narshu 0:434fd09723be 268 void RF12B::changeMode(rfmode_t _mode) {
narshu 0:434fd09723be 269 mode = _mode;
narshu 0:434fd09723be 270 if (_mode == TX) {
narshu 0:434fd09723be 271 writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
narshu 0:434fd09723be 272 } else { /* mode == RX */
narshu 0:434fd09723be 273 writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
narshu 0:434fd09723be 274 }
narshu 0:434fd09723be 275 }
narshu 0:434fd09723be 276
narshu 0:434fd09723be 277 // Interrupt routine for data reception */
narshu 0:434fd09723be 278 void RF12B::rxISR() {
narshu 0:434fd09723be 279
narshu 0:434fd09723be 280 unsigned int data = 0;
narshu 0:434fd09723be 281 static int i = -2;
narshu 0:434fd09723be 282 static unsigned char packet_length = 0;
narshu 0:434fd09723be 283 static unsigned char crc = 0;
narshu 0:434fd09723be 284 // #ifdef ROBOT_SECONDARY
narshu 0:434fd09723be 285 static unsigned char temp;
narshu 0:434fd09723be 286 // #endif
narshu 0:434fd09723be 287
narshu 0:434fd09723be 288 //Loop while interrupt is asserted
narshu 0:434fd09723be 289 while (!NIRQ_in && mode == RX) {
narshu 0:434fd09723be 290
narshu 0:434fd09723be 291 // Grab the packet's length byte
narshu 0:434fd09723be 292 if (i == -2) {
narshu 0:434fd09723be 293 data = writeCmd(0x0000);
narshu 0:434fd09723be 294 if ( (data&0x8000) ) {
narshu 0:434fd09723be 295 data = writeCmd(0xB000);
narshu 0:434fd09723be 296 packet_length = (data&0x00FF);
narshu 0:434fd09723be 297 crc = crc8(crc, packet_length);
narshu 0:434fd09723be 298 i++;
narshu 0:434fd09723be 299 }
narshu 0:434fd09723be 300 }
narshu 0:434fd09723be 301
narshu 0:434fd09723be 302 //If we exhaust the interrupt, exit
narshu 0:434fd09723be 303 if (NIRQ_in)
narshu 0:434fd09723be 304 break;
narshu 0:434fd09723be 305
narshu 0:434fd09723be 306 // Check that packet length was correct
narshu 0:434fd09723be 307 if (i == -1) {
narshu 0:434fd09723be 308 data = writeCmd(0x0000);
narshu 0:434fd09723be 309 if ( (data&0x8000) ) {
narshu 0:434fd09723be 310 data = writeCmd(0xB000);
narshu 0:434fd09723be 311 unsigned char crcofsize = (data&0x00FF);
narshu 0:434fd09723be 312 if (crcofsize != crc) {
narshu 0:434fd09723be 313 //It was wrong, start over
narshu 0:434fd09723be 314 i = -2;
narshu 0:434fd09723be 315 packet_length = 0;
narshu 0:434fd09723be 316 crc = 0;
narshu 0:434fd09723be 317 //temp = queue<unsigned char>();
narshu 0:434fd09723be 318 resetRX();
narshu 0:434fd09723be 319 } else {
narshu 0:434fd09723be 320 crc = crc8(crc, crcofsize);
narshu 0:434fd09723be 321 i++;
narshu 0:434fd09723be 322 }
narshu 0:434fd09723be 323 }
narshu 0:434fd09723be 324 }
narshu 0:434fd09723be 325
narshu 0:434fd09723be 326 //If we exhaust the interrupt, exit
narshu 0:434fd09723be 327 if (NIRQ_in)
narshu 0:434fd09723be 328 break;
narshu 0:434fd09723be 329
narshu 0:434fd09723be 330 // Grab the packet's data
narshu 0:434fd09723be 331 if (i >= 0 && i < packet_length) {
narshu 0:434fd09723be 332 data = writeCmd(0x0000);
narshu 0:434fd09723be 333 if ( (data&0x8000) ) {
narshu 0:434fd09723be 334 data = writeCmd(0xB000);
narshu 0:434fd09723be 335 // #ifdef ROBOT_SECONDARY
narshu 0:434fd09723be 336 temp = data&0x00FF;
narshu 0:434fd09723be 337 // #endif
narshu 0:434fd09723be 338 //temp.push(data&0x00FF);
narshu 0:434fd09723be 339 crc = crc8(crc, (unsigned char)(data&0x00FF));
narshu 0:434fd09723be 340 i++;
narshu 0:434fd09723be 341 }
narshu 0:434fd09723be 342 }
narshu 0:434fd09723be 343
narshu 0:434fd09723be 344 //If we exhaust the interrupt, exit
narshu 0:434fd09723be 345 if (NIRQ_in)
narshu 0:434fd09723be 346 break;
narshu 0:434fd09723be 347
narshu 0:434fd09723be 348 if (i >= packet_length) {
narshu 0:434fd09723be 349 data = writeCmd(0x0000);
narshu 0:434fd09723be 350 if ( (data&0x8000) ) {
narshu 0:434fd09723be 351 data = writeCmd(0xB000);
narshu 0:434fd09723be 352 if ((unsigned char)(data & 0x00FF) == crc) {
narshu 0:434fd09723be 353 //If the checksum is correct, add our data to the end of the output buffer
narshu 0:434fd09723be 354 //while (!temp.empty()) {
narshu 0:434fd09723be 355 //fifo.push(temp);
narshu 0:434fd09723be 356 // temp.pop();
narshu 0:434fd09723be 357 //#ifdef ROBOT_SECONDARY
narshu 0:434fd09723be 358 if (callbackfunc)
narshu 0:434fd09723be 359 (*callbackfunc)(temp);
narshu 0:434fd09723be 360
narshu 0:434fd09723be 361 if (callbackobj && mcallbackfunc)
narshu 0:434fd09723be 362 (callbackobj->*mcallbackfunc)(temp);
narshu 0:434fd09723be 363 //#endif
narshu 0:434fd09723be 364 // }
narshu 0:434fd09723be 365 }
narshu 0:434fd09723be 366
narshu 0:434fd09723be 367 // Tell RF Module we are finished, and clean up
narshu 0:434fd09723be 368 i = -2;
narshu 0:434fd09723be 369 packet_length = 0;
narshu 0:434fd09723be 370 crc = 0;
narshu 0:434fd09723be 371 //temp = queue<unsigned char>();
narshu 0:434fd09723be 372 resetRX();
narshu 0:434fd09723be 373 }
narshu 0:434fd09723be 374 }
narshu 0:434fd09723be 375 }
narshu 0:434fd09723be 376
narshu 0:434fd09723be 377 }
narshu 0:434fd09723be 378
narshu 0:434fd09723be 379 unsigned int RF12B::status() {
narshu 0:434fd09723be 380 return writeCmd(0x0000);
narshu 0:434fd09723be 381 }
narshu 0:434fd09723be 382
narshu 0:434fd09723be 383 // Tell the RF Module this packet is received and wait for the next */
narshu 0:434fd09723be 384 void RF12B::resetRX() {
narshu 0:434fd09723be 385 writeCmd(0xCA81);
narshu 0:434fd09723be 386 writeCmd(0xCA83);
narshu 0:434fd09723be 387 };
narshu 0:434fd09723be 388
narshu 0:434fd09723be 389 // Calculate CRC8 */
narshu 0:434fd09723be 390 unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
narshu 0:434fd09723be 391 crc = crc ^ data;
narshu 0:434fd09723be 392 for (int i = 0; i < 8; i++) {
narshu 0:434fd09723be 393 if (crc & 0x01) {
narshu 0:434fd09723be 394 crc = (crc >> 1) ^ 0x8C;
narshu 0:434fd09723be 395 } else {
narshu 0:434fd09723be 396 crc >>= 1;
narshu 0:434fd09723be 397 }
narshu 0:434fd09723be 398 }
narshu 0:434fd09723be 399 return crc;
narshu 0:434fd09723be 400 }