Oliver Mattos
Transmitter code for quadcopter
Diff: RF12B/RF12B.cpp
- Revision:
- 0:e6426242cacc
diff -r 000000000000 -r e6426242cacc RF12B/RF12B.cpp
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RF12B/RF12B.cpp Wed Dec 07 12:37:01 2011 +0000
@@ -0,0 +1,376 @@
+#include "RF12B.h"
+
+#include "RF_defs.h"
+#include <algorithm>
+
+RF12B::RF12B(PinName _SDI,
+ PinName _SDO,
+ PinName _SCK,
+ PinName _NCS,
+ PinName _NIRQ):spi(_SDI, _SDO, _SCK),
+ NCS(_NCS), NIRQ(_NIRQ), NIRQ_in(_NIRQ), rfled(LED3) {
+
+ /* SPI frequency, word lenght, polarity and phase */
+ spi.format(16,0);
+ spi.frequency(2000000);
+
+ /* Set ~CS high */
+ NCS = 1;
+
+ /* Initialise RF Module */
+ init();
+
+ /* Setup interrupt to happen on falling edge of NIRQ */
+ NIRQ.fall(this, &RF12B::rxISR);
+}
+
+/* Returns the packet length if data is available in the receive buffer, 0 otherwise*/
+unsigned int RF12B::available() {
+ return fifo.size();
+}
+
+/* Reads a packet of data, with length "size" Returns false if read failed. TODO: make a metafifo to isolate packets*/
+bool RF12B::read(unsigned char* data, unsigned int size) {
+ if (fifo.size() == 0) {
+ return false;
+ } else {
+ unsigned int i = 0;
+ while (fifo.size() > 0 && i < size) {
+ data[i++] = fifo.front();
+ fifo.pop();
+ }
+ return true;
+ }
+}
+
+/* Reads a byte of data from the receive buffer */
+unsigned char RF12B::read() {
+ if (available()) {
+ unsigned char data = fifo.front();
+ fifo.pop();
+ return data;
+ } else {
+ return 0xFF; // Error val although could also be data...
+ }
+}
+
+/* Sends a packet of data to the RF module for transmission TODO: Make asych*/
+void RF12B::write(unsigned char *data, unsigned char length) {
+ unsigned char crc = 0;
+
+ /* Transmitter mode */
+ changeMode(TX);
+
+ writeCmd(0x0000);
+ send(0xAA); // PREAMBLE
+ send(0xAA);
+ send(0xAA);
+ send(0x2D); // SYNC
+ send(0xD4);
+ /* Packet Length */
+ send(length);
+ crc = crc8(crc, length);
+ send(crc);
+ crc = crc8(crc, crc);
+ /* Packet Data */
+ for (unsigned char i=0; i<length; i++) {
+ send(data[i]);
+ crc = crc8(crc, data[i]);
+ }
+ send(crc);
+ send(0xAA); // DUMMY BYTES
+ send(0xAA);
+ send(0xAA);
+
+ /* Back to receiver mode */
+ changeMode(RX);
+ status();
+}
+
+/* Transmit a 1-byte data packet */
+void RF12B::write(unsigned char data) {
+ write(&data, 1);
+}
+
+void RF12B::write(queue<char> &data, int length) {
+ char crc = 0;
+ char length_byte = 0;
+
+ /* -1 means try to transmit everything in the queue */
+ if(length == -1) {
+ length = data.size();
+ }
+
+ /* max length of packet is 255 */
+ length_byte = min(length, 255);
+
+ /* Transmitter mode */
+ changeMode(TX);
+
+ writeCmd(0x0000);
+ send(0xAA); // PREAMBLE
+ send(0xAA);
+ send(0xAA);
+ send(0x2D); // SYNC
+ send(0xD4);
+ /* Packet Length */
+ send(length_byte);
+ crc = crc8(crc, length_byte);
+ send(crc);
+ crc = crc8(crc, crc);
+ /* Packet Data */
+ for (char i=0; i<length_byte; i++) {
+ send(data.front());
+ crc = crc8(crc, data.front());
+ data.pop();
+ }
+ send(crc);
+ send(0xAA); // DUMMY BYTES
+ send(0xAA);
+ send(0xAA);
+
+ /* Back to receiver mode */
+ changeMode(RX);
+ status();
+}
+
+/**********************************************************************
+ * PRIVATE FUNCTIONS
+ *********************************************************************/
+
+/* Initialises the RF12B module */
+void RF12B::init() {
+ /* writeCmd(0x80E7); //EL,EF,868band,12.0pF
+ changeMode(RX);
+ writeCmd(0xA640); //frequency select
+ writeCmd(0xC647); //4.8kbps
+ writeCmd(0x94A0); //VDI,FAST,134kHz,0dBm,-103dBm
+ writeCmd(0xC2AC); //AL,!ml,DIG,DQD4
+ writeCmd(0xCA81); //FIFO8,SYNC,!ff,DR
+ writeCmd(0xCED4); //SYNC=2DD4
+ writeCmd(0xC483); //@PWR,NO RSTRIC,!st,!fi,OE,EN
+ writeCmd(0x9850); //!mp,90kHz,MAX OUT
+ writeCmd(0xCC17); //OB1, COB0, LPX, Iddy, CDDIT�CBW0
+ writeCmd(0xE000); //NOT USED
+ writeCmd(0xC800); //NOT USED
+ writeCmd(0xC040); //1.66MHz,2.2V */
+
+ writeCmd(
+ RFM_CONFIG_EL |
+ RFM_CONFIG_EF |
+ RFM_CONFIG_BAND_433 //|
+ //RFM_CONFIG_X_11_0pf // meh, using default
+ );
+
+ // 2. Power Management Command
+ // leave everything switched off for now
+ /*
+ writeCmd(
+ RFM_POWER_MANAGEMENT // switch all off
+ );
+ */
+
+ // 3. Frequency Setting Command
+ writeCmd(
+ RFM_FREQUENCY |
+ RFM_FREQ_433Band(435.7) //I totally made this value up... if someone knows where the sweetspots are in this band, tell me!
+ );
+
+
+ // 4. Data Rate Command
+ writeCmd(RFM_DATA_RATE_9600);
+
+
+ // 5. Receiver Control Command
+ writeCmd(
+ RFM_RX_CONTROL_P20_VDI |
+ RFM_RX_CONTROL_VDI_FAST |
+ //RFM_RX_CONTROL_BW(RFM_BAUD_RATE) |
+ RFM_RX_CONTROL_BW_134 | // CHANGE THIS TO 67 TO IMPROVE RANGE! (though the bitrate must then be below 8kbaud, and fsk modulation changed)
+ RFM_RX_CONTROL_GAIN_0 |
+ RFM_RX_CONTROL_RSSI_103 // Might need adjustment. Datasheet says around 10^-5 bit error rate at this level and baudrate.
+ );
+
+ // 6. Data Filter Command
+ writeCmd(
+ RFM_DATA_FILTER_AL |
+ RFM_DATA_FILTER_ML |
+ RFM_DATA_FILTER_DIG //|
+ //RFM_DATA_FILTER_DQD(4)
+ );
+
+ // 7. FIFO and Reset Mode Command
+ writeCmd(
+ RFM_FIFO_IT(8) |
+ RFM_FIFO_DR |
+ 0x8 //turn on 16bit sync word
+ );
+
+ // 8. FIFO Syncword
+ // Leave as default: 0xD4
+
+ // 9. Receiver FIFO Read
+ // when the interupt goes high, (and if we can assume that it was a fifo fill interrupt) we can read a byte using:
+ // result = RFM_READ_FIFO();
+
+ // 10. AFC Command
+ writeCmd(
+ //RFM_AFC_AUTO_VDI | //Note this might be changed to improve range. Refer to datasheet.
+ RFM_AFC_AUTO_INDEPENDENT |
+ RFM_AFC_RANGE_LIMIT_7_8 |
+ RFM_AFC_EN |
+ RFM_AFC_OE |
+ RFM_AFC_FI
+ );
+
+ // 11. TX Configuration Control Command
+ writeCmd(
+ RFM_TX_CONTROL_MOD_60 |
+ RFM_TX_CONTROL_POW_0
+ );
+
+
+ // 12. PLL Setting Command
+ writeCmd(
+ 0xCC77 & ~0x01 // Setting the PLL bandwith, less noise, but max bitrate capped at 86.2
+ // I think this will slow down the pll's reaction time. Not sure, check with someone!
+ );
+
+ resetRX();
+ status();
+}
+
+/* Write a command to the RF Module */
+unsigned int RF12B::writeCmd(unsigned int cmd) {
+ NCS = 0;
+ unsigned int recv = spi.write(cmd);
+ NCS = 1;
+ return recv;
+}
+
+/* Sends a byte of data across RF */
+void RF12B::send(unsigned char data) {
+ while (NIRQ);
+ writeCmd(0xB800 + data);
+}
+
+/* Change the mode of the RF module to Transmitting or Receiving */
+void RF12B::changeMode(rfmode_t _mode) {
+ mode = _mode;
+ if (_mode == TX) {
+ writeCmd(0x8239); //!er,!ebb,ET,ES,EX,!eb,!ew,DC
+ } else { /* mode == RX */
+ writeCmd(0x8299); //er,!ebb,ET,ES,EX,!eb,!ew,DC
+ }
+}
+
+/* Interrupt routine for data reception */
+void RF12B::rxISR() {
+ unsigned int data = 0;
+ static int i = -2;
+ static unsigned char packet_length = 0;
+ static unsigned char crc = 0;
+ static queue<unsigned char> temp;
+
+ //Loop while interrupt is asserted
+ while (!NIRQ_in && mode == RX) {
+
+ /* Grab the packet's length byte */
+ if (i == -2) {
+ data = writeCmd(0x0000);
+ if ( (data&0x8000) ) {
+ data = writeCmd(0xB000);
+ packet_length = (data&0x00FF);
+ crc = crc8(crc, packet_length);
+ i++;
+ }
+ }
+
+ //If we exhaust the interrupt, exit
+ if (NIRQ_in)
+ break;
+
+ // Check that packet length was correct
+ if (i == -1) {
+ data = writeCmd(0x0000);
+ if ( (data&0x8000) ) {
+ data = writeCmd(0xB000);
+ unsigned char crcofsize = (data&0x00FF);
+ if (crcofsize != crc) {
+ //It was wrong, start over
+ i = -2;
+ packet_length = 0;
+ crc = 0;
+ temp = queue<unsigned char>();
+ resetRX();
+ } else {
+ crc = crc8(crc, crcofsize);
+ i++;
+ }
+ }
+ }
+
+ //If we exhaust the interrupt, exit
+ if (NIRQ_in)
+ break;
+
+ /* Grab the packet's data */
+ if (i >= 0 && i < packet_length) {
+ data = writeCmd(0x0000);
+ if ( (data&0x8000) ) {
+ data = writeCmd(0xB000);
+ temp.push(data&0x00FF);
+ crc = crc8(crc, (unsigned char)(data&0x00FF));
+ i++;
+ }
+ }
+
+ //If we exhaust the interrupt, exit
+ if (NIRQ_in)
+ break;
+
+ if (i >= packet_length) {
+ data = writeCmd(0x0000);
+ if ( (data&0x8000) ) {
+ data = writeCmd(0xB000);
+ if ((unsigned char)(data & 0x00FF) == crc) {
+ //If the checksum is correct, add our data to the end of the output buffer
+ while (!temp.empty()) {
+ fifo.push(temp.front());
+ temp.pop();
+ }
+ }
+
+ /* Tell RF Module we are finished, and clean up */
+ i = -2;
+ packet_length = 0;
+ crc = 0;
+ temp = queue<unsigned char>();
+ resetRX();
+ }
+ }
+ }
+}
+
+unsigned int RF12B::status() {
+ return writeCmd(0x0000);
+}
+
+/* Tell the RF Module this packet is received and wait for the next */
+void RF12B::resetRX() {
+ writeCmd(0xCA81);
+ writeCmd(0xCA83);
+};
+
+/* Calculate CRC8 */
+unsigned char RF12B::crc8(unsigned char crc, unsigned char data) {
+ crc = crc ^ data;
+ for (int i = 0; i < 8; i++) {
+ if (crc & 0x01) {
+ crc = (crc >> 1) ^ 0x8C;
+ } else {
+ crc >>= 1;
+ }
+ }
+ return crc;
+}
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