Prosper Van / com

xbee communication for UWB quadcopter project

Dependencies:   PwmIn

com.cpp@0:26a151d2c6db, 2014-01-08 (annotated)

Committer:
oprospero
Date:
Wed Jan 08 07:32:30 2014 +0000
Revision:
0:26a151d2c6db
Child:
1:4f53de75bc96
Create two serial instance for Rx and Tx

Who changed what in which revision?

UserRevisionLine numberNew contents of line
oprospero 0:26a151d2c6db 1 /****************************** com.cpp **********************************/
oprospero 0:26a151d2c6db 2 /* Version: 1.0 */
oprospero 0:26a151d2c6db 3 /* Last Updated: June 1, 2013 */
oprospero 0:26a151d2c6db 4 /* */
oprospero 0:26a151d2c6db 5 /* The com class implements reliable data transfer between two nodes */
oprospero 0:26a151d2c6db 6 /*using a checksum and a sequence number for guaranteed message delivery */
oprospero 0:26a151d2c6db 7 /*over an xbee modem connected to the passed in tx and rx pins. Messages */
oprospero 0:26a151d2c6db 8 /*are received and placed in the rxBuffer to be read when convenient. */
oprospero 0:26a151d2c6db 9 /*Messages are encoded by sending a byte with the value of the command */
oprospero 0:26a151d2c6db 10 /*then and int of the command. */
oprospero 0:26a151d2c6db 11 /* */
oprospero 0:26a151d2c6db 12 /* Commands: 0 -> Ack, does not get placed in rxQueue. */
oprospero 0:26a151d2c6db 13 /* 1 -> Throttle */
oprospero 0:26a151d2c6db 14 /* 2 -> Pitch */
oprospero 0:26a151d2c6db 15 /* 3 -> Roll */
oprospero 0:26a151d2c6db 16 /* 4 -> Yaw */
oprospero 0:26a151d2c6db 17 /*************************************************************************/
oprospero 0:26a151d2c6db 18
oprospero 0:26a151d2c6db 19 #include "mbed.h"
oprospero 0:26a151d2c6db 20 #include "com.h"
oprospero 0:26a151d2c6db 21
oprospero 0:26a151d2c6db 22 /*********************** com( PinName, PinName ) *************************/
oprospero 0:26a151d2c6db 23 /* */
oprospero 0:26a151d2c6db 24 /*************************************************************************/
oprospero 0:26a151d2c6db 25
oprospero 0:26a151d2c6db 26 com::com( PinName tx, PinName rx , PinName rssipin) : xbeeRx( tx, rx), xbeeTx( tx, rx), rssi(rssipin)
oprospero 0:26a151d2c6db 27 {
oprospero 0:26a151d2c6db 28 bLength = 0; // How many bytes are in the buffer.
oprospero 0:26a151d2c6db 29 xbeeRx.baud(BAUDRATE); // Setup the serial baud rate.
oprospero 0:26a151d2c6db 30 xbeeTx.baud(BAUDRATE); // Setup the serial baud rate.
oprospero 0:26a151d2c6db 31 rxBuffer = new queue(); // Point to the rxQueue.
oprospero 0:26a151d2c6db 32 signalStrength = 0;
oprospero 0:26a151d2c6db 33 xbeeRx.attach( this, &com::callback ); // Set callback as the interrupt handler.
oprospero 0:26a151d2c6db 34 xbeeTx.printf("Communication.....Done\n\r");
oprospero 0:26a151d2c6db 35 }
oprospero 0:26a151d2c6db 36
oprospero 0:26a151d2c6db 37 /************************* bool isData() ********************************/
oprospero 0:26a151d2c6db 38 /* */
oprospero 0:26a151d2c6db 39 /*************************************************************************/
oprospero 0:26a151d2c6db 40
oprospero 0:26a151d2c6db 41 bool com::isData()
oprospero 0:26a151d2c6db 42 {
oprospero 0:26a151d2c6db 43 if( rxBuffer->isEmpty() )
oprospero 0:26a151d2c6db 44 return false;
oprospero 0:26a151d2c6db 45
oprospero 0:26a151d2c6db 46 return true;
oprospero 0:26a151d2c6db 47 }
oprospero 0:26a151d2c6db 48
oprospero 0:26a151d2c6db 49 /************************ void write( char ) *****************************/
oprospero 0:26a151d2c6db 50 /* Write a packet out the xbee com port. */
oprospero 0:26a151d2c6db 51 /* */
oprospero 0:26a151d2c6db 52 /* Data format byte[] */
oprospero 0:26a151d2c6db 53 /* byte[0] = command. */
oprospero 0:26a151d2c6db 54 /* byte[1] = upper 8 bits of value. */
oprospero 0:26a151d2c6db 55 /* byte[2] = lower 8 bits of value. */
oprospero 0:26a151d2c6db 56 /* byte[3] = Checksum byte[0] + byte[2]. */
oprospero 0:26a151d2c6db 57 /* byte[4] = Sequence Number. */
oprospero 0:26a151d2c6db 58 /* byte[5] = 255 End of message. */
oprospero 0:26a151d2c6db 59 /*************************************************************************/
oprospero 0:26a151d2c6db 60
oprospero 0:26a151d2c6db 61 void com::write( short command, short value )
oprospero 0:26a151d2c6db 62 {
oprospero 0:26a151d2c6db 63 xbeeTx.putc( (char)command ); // Command
oprospero 0:26a151d2c6db 64 xbeeTx.putc( 0 ); // First 8 bits in array.
oprospero 0:26a151d2c6db 65 xbeeTx.putc( (char)value ); // Second 8 bits in array.
oprospero 0:26a151d2c6db 66 xbeeTx.putc( command + value ); // Checksum array[0] + array[1].
oprospero 0:26a151d2c6db 67 xbeeTx.putc( 0 ); // Sequence number.
oprospero 0:26a151d2c6db 68 xbeeTx.putc( 255 ); // End of message.
oprospero 0:26a151d2c6db 69 }
oprospero 0:26a151d2c6db 70
oprospero 0:26a151d2c6db 71 /*************************** char read() ********************************/
oprospero 0:26a151d2c6db 72 /* */
oprospero 0:26a151d2c6db 73 /*************************************************************************/
oprospero 0:26a151d2c6db 74
oprospero 0:26a151d2c6db 75 short * com::read()
oprospero 0:26a151d2c6db 76 {
oprospero 0:26a151d2c6db 77 if( !rxBuffer->isEmpty())
oprospero 0:26a151d2c6db 78 return rxBuffer->pop();
oprospero 0:26a151d2c6db 79
oprospero 0:26a151d2c6db 80 return NULL;
oprospero 0:26a151d2c6db 81 }
oprospero 0:26a151d2c6db 82
oprospero 0:26a151d2c6db 83 /************************ void callback() ********************************/
oprospero 0:26a151d2c6db 84 /* */
oprospero 0:26a151d2c6db 85 /*************************************************************************/
oprospero 0:26a151d2c6db 86
oprospero 0:26a151d2c6db 87 void com::callback()
oprospero 0:26a151d2c6db 88 {
oprospero 0:26a151d2c6db 89 while( xbeeRx.readable() )
oprospero 0:26a151d2c6db 90 {
oprospero 0:26a151d2c6db 91 char data = xbeeRx.getc();
oprospero 0:26a151d2c6db 92 // xbeeTx.printf("data: %d\n\r", data);
oprospero 0:26a151d2c6db 93 if( bLength++ < BUFFERSIZE )
oprospero 0:26a151d2c6db 94 buffer[bLength] = data;
oprospero 0:26a151d2c6db 95
oprospero 0:26a151d2c6db 96 if( data == 255 )
oprospero 0:26a151d2c6db 97 packetBuilder();
oprospero 0:26a151d2c6db 98 }
oprospero 0:26a151d2c6db 99 }
oprospero 0:26a151d2c6db 100
oprospero 0:26a151d2c6db 101 /********************** void packetBuilder() *****************************/
oprospero 0:26a151d2c6db 102 /* Creates a packet from the buffered data and places it in the rxBuffer */
oprospero 0:26a151d2c6db 103 /* queue to be read whenever convenient. Max value of +/- 8063. */
oprospero 0:26a151d2c6db 104 /*************************************************************************/
oprospero 0:26a151d2c6db 105
oprospero 0:26a151d2c6db 106 void com::packetBuilder()
oprospero 0:26a151d2c6db 107 {
oprospero 0:26a151d2c6db 108 char * commandData = new char[bLength];
oprospero 0:26a151d2c6db 109 commandData[4] = buffer[--bLength]; // Sequence Number.
oprospero 0:26a151d2c6db 110 commandData[3] = buffer[--bLength]; // CheckSum value.
oprospero 0:26a151d2c6db 111 commandData[2] = buffer[--bLength]; // Second 7 bits.
oprospero 0:26a151d2c6db 112 commandData[1] = buffer[--bLength]; // Fisrt 7 bits.
oprospero 0:26a151d2c6db 113 commandData[0] = buffer[--bLength]; // Command.
oprospero 0:26a151d2c6db 114
oprospero 0:26a151d2c6db 115
oprospero 0:26a151d2c6db 116 if( commandData[0] + commandData[2] == commandData[3] ) // Validate checksum.
oprospero 0:26a151d2c6db 117 {
oprospero 0:26a151d2c6db 118 short * array = new short[2];
oprospero 0:26a151d2c6db 119
oprospero 0:26a151d2c6db 120 array[0] = (short)commandData[0];
oprospero 0:26a151d2c6db 121
oprospero 0:26a151d2c6db 122 short value = (short)(commandData[1] * 128 + commandData[2]);
oprospero 0:26a151d2c6db 123
oprospero 0:26a151d2c6db 124 if( value > 8062 )
oprospero 0:26a151d2c6db 125 value = (short)value + 57344;
oprospero 0:26a151d2c6db 126
oprospero 0:26a151d2c6db 127 array[1] = value;
oprospero 0:26a151d2c6db 128 // xbeeTx.printf("Cmd: %d,\tVal: %d\n\r,",array[0],array[1]);
oprospero 0:26a151d2c6db 129 rxBuffer->add( array ); // Add to read buffer.
oprospero 0:26a151d2c6db 130 write( (short)commandData[0], (short)commandData[4]); // Ack the packet with sequence nuber.
oprospero 0:26a151d2c6db 131 }
oprospero 0:26a151d2c6db 132 delete[] commandData;
oprospero 0:26a151d2c6db 133 bLength = 0; // Reset the buffer length.
oprospero 0:26a151d2c6db 134 }
oprospero 0:26a151d2c6db 135
oprospero 0:26a151d2c6db 136
oprospero 0:26a151d2c6db 137 /********************** bool isSignalGood() ******************************/
oprospero 0:26a151d2c6db 138 /* For future use */
oprospero 0:26a151d2c6db 139 /*************************************************************************/
oprospero 0:26a151d2c6db 140 bool com::isSignalGood()
oprospero 0:26a151d2c6db 141 {
oprospero 0:26a151d2c6db 142 signalStrength = rssi.dutycycle();
oprospero 0:26a151d2c6db 143 if (signalStrength > RSSI_THRES) return true;
oprospero 0:26a151d2c6db 144 else return false;
oprospero 0:26a151d2c6db 145 }
oprospero 0:26a151d2c6db 146