This is for ICRS\' second generation Quadcopter

Dependencies:   mbed

Revision:
0:0bbf2f16da9c
diff -r 000000000000 -r 0bbf2f16da9c RF12B/RF12B.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/RF12B/RF12B.cpp	Fri Nov 18 18:23:33 2011 +0000
@@ -0,0 +1,377 @@
+#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&#65533;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!
+    );
+
+    changeMode(RX);
+    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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