Harry Eakins / RF12B

Library to send and receive data using RF12B transceiver modules Big thanks to the tutorial at https://loee.jottit.com/rfm12b_and_avr_-_quick_start and madcowswe

Dependents:   Measure_system Quadcopter_copy

RF12B.cpp@6:98da0571ec31, 2011-03-11 (annotated)

Committer:
harryeakins
Date:
Fri Mar 11 15:47:06 2011 +0000
Revision:
6:98da0571ec31
Parent:
5:a92c3f6d1711
Child:
7:9f9e2a63a8a2
Added RFSerial

Who changed what in which revision?

UserRevisionLine numberNew contents of line
harryeakins 3:e72ad65868ab 1 #include "RF12B.h"
harryeakins 3:e72ad65868ab 2
harryeakins 6:98da0571ec31 3 #include "RF_defs.h"
harryeakins 6:98da0571ec31 4
harryeakins 5:a92c3f6d1711 5 DigitalOut rfled(LED3);
harryeakins 5:a92c3f6d1711 6
harryeakins 4:2a295db9ba1a 7 RF12B::RF12B(PinName _SDI,
harryeakins 4:2a295db9ba1a 8 PinName _SDO,
harryeakins 4:2a295db9ba1a 9 PinName _SCK,
harryeakins 4:2a295db9ba1a 10 PinName _NCS,
harryeakins 4:2a295db9ba1a 11 PinName _NIRQ):spi(_SDI, _SDO, _SCK),
harryeakins 5:a92c3f6d1711 12 NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ), rfled(LED3) {
harryeakins 3:e72ad65868ab 13
harryeakins 4:2a295db9ba1a 14 /* SPI frequency, word lenght, polarity and phase */
harryeakins 4:2a295db9ba1a 15 spi.format(16,0);
harryeakins 4:2a295db9ba1a 16 spi.frequency(2000000);
harryeakins 4:2a295db9ba1a 17
harryeakins 4:2a295db9ba1a 18 /* Set ~CS high */
harryeakins 4:2a295db9ba1a 19 NCS = 1;
harryeakins 3:e72ad65868ab 20
harryeakins 4:2a295db9ba1a 21 /* Initialise RF Module */
harryeakins 3:e72ad65868ab 22 init();
harryeakins 4:2a295db9ba1a 23
harryeakins 4:2a295db9ba1a 24 /* Setup interrupt to happen on falling edge of NIRQ */
harryeakins 4:2a295db9ba1a 25 NIRQ.fall(this, &RF12B::rxISR);
harryeakins 3:e72ad65868ab 26 }
harryeakins 3:e72ad65868ab 27
harryeakins 4:2a295db9ba1a 28 /* Returns true if receive buffer contains data */
harryeakins 4:2a295db9ba1a 29 bool RF12B::available() {
harryeakins 4:2a295db9ba1a 30 return !fifo.empty();
harryeakins 4:2a295db9ba1a 31 }
harryeakins 3:e72ad65868ab 32
harryeakins 4:2a295db9ba1a 33 /* Reads a byte of data from the receive buffer */
harryeakins 3:e72ad65868ab 34 unsigned char RF12B::read() {
harryeakins 4:2a295db9ba1a 35 if (available()) {
harryeakins 4:2a295db9ba1a 36 unsigned char data = fifo.front();
harryeakins 4:2a295db9ba1a 37 fifo.pop();
harryeakins 4:2a295db9ba1a 38 return data;
harryeakins 4:2a295db9ba1a 39 } else {
harryeakins 4:2a295db9ba1a 40 return 0xFF; // Error val although could also be data...
harryeakins 3:e72ad65868ab 41 }
harryeakins 3:e72ad65868ab 42 }
harryeakins 3:e72ad65868ab 43
harryeakins 5:a92c3f6d1711 44 /* Sends a packet of data to the RF module for transmission */
harryeakins 4:2a295db9ba1a 45 void RF12B::write(unsigned char *data, unsigned char length) {
harryeakins 6:98da0571ec31 46 unsigned char crc = 0;
harryeakins 4:2a295db9ba1a 47 /* Transmitter mode */
harryeakins 4:2a295db9ba1a 48 changeMode(TX);
harryeakins 4:2a295db9ba1a 49
harryeakins 3:e72ad65868ab 50 writeCmd(0x0000);
harryeakins 3:e72ad65868ab 51 send(0xAA); // PREAMBLE
harryeakins 3:e72ad65868ab 52 send(0xAA);
harryeakins 3:e72ad65868ab 53 send(0xAA);
harryeakins 3:e72ad65868ab 54 send(0x2D); // SYNC
harryeakins 3:e72ad65868ab 55 send(0xD4);
harryeakins 4:2a295db9ba1a 56 /* Packet Length */
harryeakins 4:2a295db9ba1a 57 send(length);
harryeakins 6:98da0571ec31 58 crc = crc8(crc, length);
harryeakins 4:2a295db9ba1a 59 /* Packet Data */
harryeakins 4:2a295db9ba1a 60 for (unsigned char i=0; i<length; i++) {
harryeakins 3:e72ad65868ab 61 send(data[i]);
harryeakins 6:98da0571ec31 62 crc = crc8(crc, data[i]);
harryeakins 3:e72ad65868ab 63 }
harryeakins 6:98da0571ec31 64 send(crc);
harryeakins 3:e72ad65868ab 65 send(0xAA); // DUMMY BYTES
harryeakins 3:e72ad65868ab 66 send(0xAA);
harryeakins 3:e72ad65868ab 67 send(0xAA);
harryeakins 3:e72ad65868ab 68
harryeakins 4:2a295db9ba1a 69 /* Back to receiver mode */
harryeakins 4:2a295db9ba1a 70 changeMode(RX);
harryeakins 5:a92c3f6d1711 71 status();
harryeakins 3:e72ad65868ab 72 }
harryeakins 3:e72ad65868ab 73
harryeakins 4:2a295db9ba1a 74 /* Transmit a 1-byte data packet */
harryeakins 4:2a295db9ba1a 75 void RF12B::write(unsigned char data) {
harryeakins 4:2a295db9ba1a 76 write(&data, 1);
harryeakins 3:e72ad65868ab 77 }
harryeakins 3:e72ad65868ab 78
harryeakins 4:2a295db9ba1a 79 /**********************************************************************
harryeakins 4:2a295db9ba1a 80 * PRIVATE FUNCTIONS
harryeakins 4:2a295db9ba1a 81 *********************************************************************/
harryeakins 3:e72ad65868ab 82
harryeakins 4:2a295db9ba1a 83 /* Initialises the RF12B module */
harryeakins 3:e72ad65868ab 84 void RF12B::init() {
harryeakins 6:98da0571ec31 85 /* writeCmd(0x80E7); //EL,EF,868band,12.0pF
harryeakins 6:98da0571ec31 86 changeMode(RX);
harryeakins 6:98da0571ec31 87 writeCmd(0xA640); //frequency select
harryeakins 6:98da0571ec31 88 writeCmd(0xC647); //4.8kbps
harryeakins 6:98da0571ec31 89 writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
harryeakins 6:98da0571ec31 90 writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
harryeakins 6:98da0571ec31 91 writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
harryeakins 6:98da0571ec31 92 writeCmd(0xCED4); //SYNC=2DD4
harryeakins 6:98da0571ec31 93 writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
harryeakins 6:98da0571ec31 94 writeCmd(0x9850); //!mp,90kHz,MAX OUT
harryeakins 6:98da0571ec31 95 writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT�CBW0
harryeakins 6:98da0571ec31 96 writeCmd(0xE000); //NOT USED
harryeakins 6:98da0571ec31 97 writeCmd(0xC800); //NOT USED
harryeakins 6:98da0571ec31 98 writeCmd(0xC040); //1.66MHz,2.2V */
harryeakins 6:98da0571ec31 99
harryeakins 6:98da0571ec31 100 writeCmd(
harryeakins 6:98da0571ec31 101 RFM_CONFIG_EL |
harryeakins 6:98da0571ec31 102 RFM_CONFIG_EF |
harryeakins 6:98da0571ec31 103 RFM_CONFIG_BAND_433 //|
harryeakins 6:98da0571ec31 104 //RFM_CONFIG_X_11_0pf // meh, using default
harryeakins 6:98da0571ec31 105 );
harryeakins 6:98da0571ec31 106
harryeakins 6:98da0571ec31 107 // 2. Power Management Command
harryeakins 6:98da0571ec31 108 // leave everything switched off for now
harryeakins 6:98da0571ec31 109 /*
harryeakins 6:98da0571ec31 110 writeCmd(
harryeakins 6:98da0571ec31 111 RFM_POWER_MANAGEMENT // switch all off
harryeakins 6:98da0571ec31 112 );
harryeakins 6:98da0571ec31 113 */
harryeakins 6:98da0571ec31 114
harryeakins 6:98da0571ec31 115 // 3. Frequency Setting Command
harryeakins 6:98da0571ec31 116 writeCmd(
harryeakins 6:98da0571ec31 117 RFM_FREQUENCY |
harryeakins 6:98da0571ec31 118 RFM_FREQ_433Band(435.7) //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
harryeakins 6:98da0571ec31 119 );
harryeakins 6:98da0571ec31 120
harryeakins 6:98da0571ec31 121
harryeakins 6:98da0571ec31 122 // 4. Data Rate Command
harryeakins 6:98da0571ec31 123 writeCmd(RFM_DATA_RATE_9600);
harryeakins 6:98da0571ec31 124
harryeakins 6:98da0571ec31 125
harryeakins 6:98da0571ec31 126 // 5. Receiver Control Command
harryeakins 6:98da0571ec31 127 writeCmd(
harryeakins 6:98da0571ec31 128 RFM_RX_CONTROL_P20_VDI |
harryeakins 6:98da0571ec31 129 RFM_RX_CONTROL_VDI_FAST |
harryeakins 6:98da0571ec31 130 //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
harryeakins 6:98da0571ec31 131 RFM_RX_CONTROL_BW_134 | // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
harryeakins 6:98da0571ec31 132 RFM_RX_CONTROL_GAIN_0 |
harryeakins 6:98da0571ec31 133 RFM_RX_CONTROL_RSSI_103 // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
harryeakins 6:98da0571ec31 134 );
harryeakins 6:98da0571ec31 135
harryeakins 6:98da0571ec31 136 // 6. Data Filter Command
harryeakins 6:98da0571ec31 137 writeCmd(
harryeakins 6:98da0571ec31 138 RFM_DATA_FILTER_AL |
harryeakins 6:98da0571ec31 139 RFM_DATA_FILTER_ML |
harryeakins 6:98da0571ec31 140 RFM_DATA_FILTER_DIG //|
harryeakins 6:98da0571ec31 141 //RFM_DATA_FILTER_DQD(4)
harryeakins 6:98da0571ec31 142 );
harryeakins 6:98da0571ec31 143
harryeakins 6:98da0571ec31 144 // 7. FIFO and Reset Mode Command
harryeakins 6:98da0571ec31 145 writeCmd(
harryeakins 6:98da0571ec31 146 RFM_FIFO_IT(8) |
harryeakins 6:98da0571ec31 147 RFM_FIFO_DR |
harryeakins 6:98da0571ec31 148 0x8 //turn on 16bit sync word
harryeakins 6:98da0571ec31 149 );
harryeakins 6:98da0571ec31 150
harryeakins 6:98da0571ec31 151 // 8. FIFO Syncword
harryeakins 6:98da0571ec31 152 // Leave as default: 0xD4
harryeakins 6:98da0571ec31 153
harryeakins 6:98da0571ec31 154 // 9. Receiver FIFO Read
harryeakins 6:98da0571ec31 155 // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
harryeakins 6:98da0571ec31 156 // result = RFM_READ_FIFO();
harryeakins 6:98da0571ec31 157
harryeakins 6:98da0571ec31 158 // 10. AFC Command
harryeakins 6:98da0571ec31 159 writeCmd(
harryeakins 6:98da0571ec31 160 //RFM_AFC_AUTO_VDI | //Note this might be changed to improve range. Refer to datasheet.
harryeakins 6:98da0571ec31 161 RFM_AFC_AUTO_INDEPENDENT |
harryeakins 6:98da0571ec31 162 RFM_AFC_RANGE_LIMIT_7_8 |
harryeakins 6:98da0571ec31 163 RFM_AFC_EN |
harryeakins 6:98da0571ec31 164 RFM_AFC_OE |
harryeakins 6:98da0571ec31 165 RFM_AFC_FI
harryeakins 6:98da0571ec31 166 );
harryeakins 6:98da0571ec31 167
harryeakins 6:98da0571ec31 168 // 11. TX Configuration Control Command
harryeakins 6:98da0571ec31 169 writeCmd(
harryeakins 6:98da0571ec31 170 RFM_TX_CONTROL_MOD_60 |
harryeakins 6:98da0571ec31 171 RFM_TX_CONTROL_POW_0
harryeakins 6:98da0571ec31 172 );
harryeakins 6:98da0571ec31 173
harryeakins 6:98da0571ec31 174
harryeakins 6:98da0571ec31 175 // 12. PLL Setting Command
harryeakins 6:98da0571ec31 176 writeCmd(
harryeakins 6:98da0571ec31 177 0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
harryeakins 6:98da0571ec31 178 // I think this will slow down the plls reaction time. Not sure, check with someone!
harryeakins 6:98da0571ec31 179 );
harryeakins 5:a92c3f6d1711 180
harryeakins 5:a92c3f6d1711 181 resetRX();
harryeakins 5:a92c3f6d1711 182 status();
harryeakins 4:2a295db9ba1a 183 }
harryeakins 3:e72ad65868ab 184
harryeakins 4:2a295db9ba1a 185 /* Write a command to the RF Module */
harryeakins 4:2a295db9ba1a 186 unsigned int RF12B::writeCmd(unsigned int cmd) {
harryeakins 4:2a295db9ba1a 187 NCS = 0;
harryeakins 4:2a295db9ba1a 188 unsigned int recv = spi.write(cmd);
harryeakins 4:2a295db9ba1a 189 NCS = 1;
harryeakins 4:2a295db9ba1a 190 return recv;
harryeakins 3:e72ad65868ab 191 }
harryeakins 3:e72ad65868ab 192
harryeakins 4:2a295db9ba1a 193 /* Sends a byte of data across RF */
harryeakins 4:2a295db9ba1a 194 void RF12B::send(unsigned char data) {
harryeakins 4:2a295db9ba1a 195 while (NIRQ);
harryeakins 4:2a295db9ba1a 196 writeCmd(0xB800 + data);
harryeakins 4:2a295db9ba1a 197 }
harryeakins 4:2a295db9ba1a 198
harryeakins 4:2a295db9ba1a 199 /* Change the mode of the RF module to Transmitting or Receiving */
harryeakins 4:2a295db9ba1a 200 void RF12B::changeMode(rfmode_t mode) {
harryeakins 4:2a295db9ba1a 201 if (mode == TX) {
harryeakins 3:e72ad65868ab 202 writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
harryeakins 4:2a295db9ba1a 203 } else { /* mode == RX */
harryeakins 3:e72ad65868ab 204 writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
harryeakins 3:e72ad65868ab 205 }
harryeakins 3:e72ad65868ab 206 }
harryeakins 3:e72ad65868ab 207
harryeakins 4:2a295db9ba1a 208 /* Interrupt routine for data reception */
harryeakins 4:2a295db9ba1a 209 void RF12B::rxISR() {
harryeakins 4:2a295db9ba1a 210 unsigned int data = 0, i = 0;
harryeakins 4:2a295db9ba1a 211 unsigned char packet_length = 0;
harryeakins 6:98da0571ec31 212 unsigned char crc = 0;
harryeakins 6:98da0571ec31 213 queue<unsigned char> temp;
harryeakins 4:2a295db9ba1a 214
harryeakins 4:2a295db9ba1a 215 /* Grab the packet's length byte */
harryeakins 4:2a295db9ba1a 216 data = writeCmd(0x0000);
harryeakins 4:2a295db9ba1a 217 if ( (data&0x8000) ) {
harryeakins 4:2a295db9ba1a 218 data = writeCmd(0xB000);
harryeakins 4:2a295db9ba1a 219 packet_length = (data&0x00FF);
harryeakins 6:98da0571ec31 220 crc = crc8(crc, packet_length);
harryeakins 4:2a295db9ba1a 221 }
harryeakins 5:a92c3f6d1711 222
harryeakins 4:2a295db9ba1a 223 /* Grab the packet's data */
harryeakins 5:a92c3f6d1711 224 while (i < packet_length) {
harryeakins 5:a92c3f6d1711 225 if (!NIRQ_in) {
harryeakins 5:a92c3f6d1711 226 data = writeCmd(0x0000);
harryeakins 5:a92c3f6d1711 227 if ( (data&0x8000) ) {
harryeakins 5:a92c3f6d1711 228 data = writeCmd(0xB000);
harryeakins 6:98da0571ec31 229 temp.push(data&0x00FF);
harryeakins 6:98da0571ec31 230 crc = crc8(crc, (unsigned char)(data&0x00FF));
harryeakins 5:a92c3f6d1711 231 i++;
harryeakins 5:a92c3f6d1711 232 }
harryeakins 4:2a295db9ba1a 233 }
harryeakins 4:2a295db9ba1a 234 }
harryeakins 6:98da0571ec31 235 while (1) {
harryeakins 6:98da0571ec31 236 if (!NIRQ_in) {
harryeakins 6:98da0571ec31 237 data = writeCmd(0x0000);
harryeakins 6:98da0571ec31 238 if ( (data&0x8000) ) {
harryeakins 6:98da0571ec31 239 data = writeCmd(0xB000);
harryeakins 6:98da0571ec31 240 if ((unsigned char)(data & 0x00FF) == crc) {
harryeakins 6:98da0571ec31 241 while (!temp.empty()) {
harryeakins 6:98da0571ec31 242 fifo.push(temp.front());
harryeakins 6:98da0571ec31 243 temp.pop();
harryeakins 6:98da0571ec31 244 }
harryeakins 6:98da0571ec31 245 }
harryeakins 6:98da0571ec31 246 break;
harryeakins 6:98da0571ec31 247 }
harryeakins 6:98da0571ec31 248 }
harryeakins 6:98da0571ec31 249 }
harryeakins 4:2a295db9ba1a 250 /* Tell RF Module we are finished */
harryeakins 4:2a295db9ba1a 251 resetRX();
harryeakins 3:e72ad65868ab 252 }
harryeakins 4:2a295db9ba1a 253
harryeakins 5:a92c3f6d1711 254 unsigned int RF12B::status() {
harryeakins 5:a92c3f6d1711 255 return writeCmd(0x0000);
harryeakins 5:a92c3f6d1711 256 }
harryeakins 5:a92c3f6d1711 257
harryeakins 4:2a295db9ba1a 258 /* Tell the RF Module this packet is received and wait for the next */
harryeakins 4:2a295db9ba1a 259 void RF12B::resetRX() {
harryeakins 4:2a295db9ba1a 260 writeCmd(0xCA81);
harryeakins 4:2a295db9ba1a 261 writeCmd(0xCA83);
harryeakins 6:98da0571ec31 262 };
harryeakins 6:98da0571ec31 263
harryeakins 6:98da0571ec31 264 /* Calculate CRC8 */
harryeakins 6:98da0571ec31 265 unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
harryeakins 6:98da0571ec31 266 crc = crc ^ data;
harryeakins 6:98da0571ec31 267 for (int i = 0; i < 8; i++) {
harryeakins 6:98da0571ec31 268 if (crc & 0x01) {
harryeakins 6:98da0571ec31 269 crc = (crc >> 1) ^ 0x8C;
harryeakins 6:98da0571ec31 270 } else {
harryeakins 6:98da0571ec31 271 crc >>= 1;
harryeakins 6:98da0571ec31 272 }
harryeakins 6:98da0571ec31 273 }
harryeakins 6:98da0571ec31 274 return crc;
harryeakins 6:98da0571ec31 275 }