Prosper Van / xbeeCom

xbee communication for UWB quadcopter project Originally by Greg Abdo Forking to reduce impact of interrupt by moving packetbuilder out of the interrupt and letting be handled in the main loop

Fork of com by Prosper Van

com.cpp@5:7cdf299ea7a4, 2014-04-22 (annotated)

Committer:
oprospero
Date:
Tue Apr 22 06:28:49 2014 +0000
Revision:
5:7cdf299ea7a4
Parent:
4:f8e953201251
Child:
6:4d96c8776442
fixed previous commit. Added txQueue initialization

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 1:4f53de75bc96 22
oprospero 0:26a151d2c6db 23 /*********************** com( PinName, PinName ) *************************/
oprospero 0:26a151d2c6db 24 /* */
oprospero 0:26a151d2c6db 25 /*************************************************************************/
oprospero 0:26a151d2c6db 26
oprospero 2:bd1621102cad 27 com::com( PinName tx, PinName rx , PinName rssipin) : xbeeTx( tx, NC), xbeeRx( NC, rx), rssi(rssipin)
oprospero 0:26a151d2c6db 28 {
oprospero 0:26a151d2c6db 29 bLength = 0; // How many bytes are in the buffer.
oprospero 2:bd1621102cad 30 api_mode = false; // Xbee is in transparent mode.
oprospero 1:4f53de75bc96 31 xbeeTx.baud(BAUDRATE); // Setup the serial baud rate.
oprospero 0:26a151d2c6db 32 xbeeRx.baud(BAUDRATE); // Setup the serial baud rate.
oprospero 0:26a151d2c6db 33 rxBuffer = new queue(); // Point to the rxQueue.
oprospero 5:7cdf299ea7a4 34 txBuffer = new queue();
oprospero 0:26a151d2c6db 35 signalStrength = 0;
oprospero 0:26a151d2c6db 36 xbeeRx.attach( this, &com::callback ); // Set callback as the interrupt handler.
oprospero 1:4f53de75bc96 37 #ifdef DEBUG
oprospero 0:26a151d2c6db 38 xbeeTx.printf("Communication.....Done\n\r");
oprospero 1:4f53de75bc96 39 #endif
oprospero 0:26a151d2c6db 40 }
oprospero 0:26a151d2c6db 41
oprospero 0:26a151d2c6db 42 /************************* bool isData() ********************************/
oprospero 0:26a151d2c6db 43 /* */
oprospero 0:26a151d2c6db 44 /*************************************************************************/
oprospero 0:26a151d2c6db 45
oprospero 0:26a151d2c6db 46 bool com::isData()
oprospero 0:26a151d2c6db 47 {
oprospero 2:bd1621102cad 48
oprospero 1:4f53de75bc96 49 return !rxBuffer->isEmpty();
oprospero 0:26a151d2c6db 50 }
oprospero 0:26a151d2c6db 51
oprospero 0:26a151d2c6db 52 /************************ void write( char ) *****************************/
oprospero 0:26a151d2c6db 53 /* Write a packet out the xbee com port. */
oprospero 0:26a151d2c6db 54 /* */
oprospero 0:26a151d2c6db 55 /* Data format byte[] */
oprospero 0:26a151d2c6db 56 /* byte[0] = command. */
oprospero 0:26a151d2c6db 57 /* byte[1] = upper 8 bits of value. */
oprospero 0:26a151d2c6db 58 /* byte[2] = lower 8 bits of value. */
oprospero 0:26a151d2c6db 59 /* byte[3] = Checksum byte[0] + byte[2]. */
oprospero 0:26a151d2c6db 60 /* byte[4] = Sequence Number. */
oprospero 0:26a151d2c6db 61 /* byte[5] = 255 End of message. */
oprospero 0:26a151d2c6db 62 /*************************************************************************/
oprospero 0:26a151d2c6db 63
oprospero 0:26a151d2c6db 64 void com::write( short command, short value )
oprospero 0:26a151d2c6db 65 {
oprospero 2:bd1621102cad 66 if (api_mode)
oprospero 2:bd1621102cad 67 {
oprospero 2:bd1621102cad 68 short hvalue = value / 128;
oprospero 2:bd1621102cad 69 short lvalue = (value % 128);
oprospero 2:bd1621102cad 70 short sum = (2*command + hvalue + 2*lvalue + value);
oprospero 2:bd1621102cad 71 short check = sum % 256;
oprospero 2:bd1621102cad 72 xbeeTx.putc( (char) 127); //Start Delimiter
oprospero 2:bd1621102cad 73
oprospero 2:bd1621102cad 74 xbeeTx.putc( (char) 0); //Frame Data Length MSB
oprospero 2:bd1621102cad 75 xbeeTx.putc( (char) 6); //Frame Data Length LSB
oprospero 2:bd1621102cad 76 //Frame Data
oprospero 2:bd1621102cad 77 xbeeTx.putc( (char) command); // Command
oprospero 2:bd1621102cad 78 xbeeTx.putc( (char) hvalue); // First 8 bits in array.
oprospero 2:bd1621102cad 79 xbeeTx.putc( (char) lvalue); // Second 8 bits in array.
oprospero 2:bd1621102cad 80 xbeeTx.putc( command + lvalue ); // Checksum array[0] + array[1].
oprospero 2:bd1621102cad 81 xbeeTx.putc( (char) value); // Sequence number.
oprospero 2:bd1621102cad 82 xbeeTx.putc( 255 ); // End of message.
oprospero 2:bd1621102cad 83
oprospero 2:bd1621102cad 84 xbeeTx.putc( (char) 255 - check); //Checksum
oprospero 2:bd1621102cad 85
oprospero 2:bd1621102cad 86 }
oprospero 2:bd1621102cad 87 else
oprospero 2:bd1621102cad 88 {
oprospero 2:bd1621102cad 89 short lvalue = (value % 128);
oprospero 2:bd1621102cad 90 xbeeTx.putc( (char)command ); // Command
oprospero 2:bd1621102cad 91 xbeeTx.putc( (char) value / 128 ); // First 8 bits in array.
oprospero 2:bd1621102cad 92 xbeeTx.putc( (char) lvalue); // Second 8 bits in array.
oprospero 2:bd1621102cad 93 xbeeTx.putc( command + lvalue ); // Checksum array[0] + array[1].
oprospero 2:bd1621102cad 94 xbeeTx.putc( (char)value ); // Sequence number.
oprospero 2:bd1621102cad 95 xbeeTx.putc( 255 ); // End of message.
oprospero 2:bd1621102cad 96 }
oprospero 0:26a151d2c6db 97 }
oprospero 0:26a151d2c6db 98
oprospero 5:7cdf299ea7a4 99 /*************************** char ackCheck() ********************************/
oprospero 0:26a151d2c6db 100 /* */
oprospero 0:26a151d2c6db 101 /*************************************************************************/
oprospero 0:26a151d2c6db 102
oprospero 4:f8e953201251 103 void com::ackCheck()
oprospero 4:f8e953201251 104 {
oprospero 5:7cdf299ea7a4 105 if( !txBuffer->isEmpty() && xbeeTx.writeable())
oprospero 4:f8e953201251 106 {
oprospero 5:7cdf299ea7a4 107 short * pkt = txBuffer->pop();
oprospero 5:7cdf299ea7a4 108 write(pkt[0],pkt[1]); //may need to disable interrupt
oprospero 5:7cdf299ea7a4 109 delete[] pkt;
oprospero 4:f8e953201251 110 }
oprospero 4:f8e953201251 111
oprospero 4:f8e953201251 112 }
oprospero 4:f8e953201251 113
oprospero 5:7cdf299ea7a4 114 bool com::rdy2ack()
oprospero 5:7cdf299ea7a4 115 {
oprospero 5:7cdf299ea7a4 116 return !txBuffer->isEmpty();
oprospero 5:7cdf299ea7a4 117 }
oprospero 4:f8e953201251 118
oprospero 4:f8e953201251 119 /*************************** char read() ********************************/
oprospero 4:f8e953201251 120 /* */
oprospero 4:f8e953201251 121 /*************************************************************************/
oprospero 4:f8e953201251 122
oprospero 0:26a151d2c6db 123 short * com::read()
oprospero 0:26a151d2c6db 124 {
oprospero 0:26a151d2c6db 125 if( !rxBuffer->isEmpty())
oprospero 0:26a151d2c6db 126 return rxBuffer->pop();
oprospero 0:26a151d2c6db 127
oprospero 0:26a151d2c6db 128 return NULL;
oprospero 0:26a151d2c6db 129 }
oprospero 0:26a151d2c6db 130
oprospero 0:26a151d2c6db 131 /************************ void callback() ********************************/
oprospero 0:26a151d2c6db 132 /* */
oprospero 0:26a151d2c6db 133 /*************************************************************************/
oprospero 0:26a151d2c6db 134
oprospero 0:26a151d2c6db 135 void com::callback()
oprospero 0:26a151d2c6db 136 {
oprospero 4:f8e953201251 137 __disable_irq();
oprospero 0:26a151d2c6db 138 while( xbeeRx.readable() )
oprospero 0:26a151d2c6db 139 {
oprospero 0:26a151d2c6db 140 char data = xbeeRx.getc();
oprospero 0:26a151d2c6db 141 // xbeeTx.printf("data: %d\n\r", data);
oprospero 2:bd1621102cad 142 // xbeeTx.printf("%d %d", data,(char) 255);
oprospero 2:bd1621102cad 143 // xbeeTx.putc( data );
oprospero 0:26a151d2c6db 144 if( bLength++ < BUFFERSIZE )
oprospero 0:26a151d2c6db 145 buffer[bLength] = data;
oprospero 4:f8e953201251 146 //
oprospero 4:f8e953201251 147 // xbeeTx.putc( bLength );
oprospero 4:f8e953201251 148 // xbeeTx.putc( bLength );
oprospero 4:f8e953201251 149 // xbeeTx.putc( 255 );
oprospero 0:26a151d2c6db 150 if( data == 255 )
oprospero 0:26a151d2c6db 151 packetBuilder();
oprospero 0:26a151d2c6db 152 }
oprospero 4:f8e953201251 153 __enable_irq();
oprospero 0:26a151d2c6db 154 }
oprospero 0:26a151d2c6db 155
oprospero 2:bd1621102cad 156 //void com::api_callback()
oprospero 2:bd1621102cad 157 //{
oprospero 2:bd1621102cad 158 // while( xbeeRx.readable() )
oprospero 2:bd1621102cad 159 // {
oprospero 2:bd1621102cad 160 // buffer[bLength++] = xbeeRx.getc();
oprospero 2:bd1621102cad 161 // }
oprospero 2:bd1621102cad 162 //}
oprospero 2:bd1621102cad 163
oprospero 2:bd1621102cad 164
oprospero 0:26a151d2c6db 165 /********************** void packetBuilder() *****************************/
oprospero 0:26a151d2c6db 166 /* Creates a packet from the buffered data and places it in the rxBuffer */
oprospero 0:26a151d2c6db 167 /* queue to be read whenever convenient. Max value of +/- 8063. */
oprospero 0:26a151d2c6db 168 /*************************************************************************/
oprospero 0:26a151d2c6db 169
oprospero 0:26a151d2c6db 170 void com::packetBuilder()
oprospero 0:26a151d2c6db 171 {
oprospero 0:26a151d2c6db 172 char * commandData = new char[bLength];
oprospero 0:26a151d2c6db 173 commandData[4] = buffer[--bLength]; // Sequence Number.
oprospero 0:26a151d2c6db 174 commandData[3] = buffer[--bLength]; // CheckSum value.
oprospero 0:26a151d2c6db 175 commandData[2] = buffer[--bLength]; // Second 7 bits.
oprospero 0:26a151d2c6db 176 commandData[1] = buffer[--bLength]; // Fisrt 7 bits.
oprospero 0:26a151d2c6db 177 commandData[0] = buffer[--bLength]; // Command.
oprospero 0:26a151d2c6db 178
oprospero 0:26a151d2c6db 179
oprospero 0:26a151d2c6db 180 if( commandData[0] + commandData[2] == commandData[3] ) // Validate checksum.
oprospero 0:26a151d2c6db 181 {
oprospero 0:26a151d2c6db 182 short * array = new short[2];
oprospero 0:26a151d2c6db 183
oprospero 0:26a151d2c6db 184 array[0] = (short)commandData[0];
oprospero 0:26a151d2c6db 185
oprospero 0:26a151d2c6db 186 short value = (short)(commandData[1] * 128 + commandData[2]);
oprospero 0:26a151d2c6db 187
oprospero 0:26a151d2c6db 188 if( value > 8062 )
oprospero 0:26a151d2c6db 189 value = (short)value + 57344;
oprospero 0:26a151d2c6db 190
oprospero 0:26a151d2c6db 191 array[1] = value;
oprospero 0:26a151d2c6db 192 // xbeeTx.printf("Cmd: %d,\tVal: %d\n\r,",array[0],array[1]);
oprospero 0:26a151d2c6db 193 rxBuffer->add( array ); // Add to read buffer.
oprospero 2:bd1621102cad 194 // xbeeTx.putc( 255 );
oprospero 2:bd1621102cad 195 // xbeeTx.putc( 255 );
oprospero 4:f8e953201251 196 if ( commandData[0] != 0 )
oprospero 4:f8e953201251 197 {
oprospero 4:f8e953201251 198 short * ackPacket = new short[2];
oprospero 4:f8e953201251 199 ackPacket[1] = commandData[0];
oprospero 4:f8e953201251 200 ackPacket[1] = commandData[4];
oprospero 4:f8e953201251 201 txBuffer->add( ackPacket ); // Ack the packet with sequence nuber.
oprospero 4:f8e953201251 202 }
oprospero 0:26a151d2c6db 203 }
oprospero 0:26a151d2c6db 204 delete[] commandData;
oprospero 0:26a151d2c6db 205 bLength = 0; // Reset the buffer length.
oprospero 0:26a151d2c6db 206 }
oprospero 2:bd1621102cad 207 //
oprospero 2:bd1621102cad 208 //void com::api_packetBuilder()
oprospero 2:bd1621102cad 209 //{
oprospero 2:bd1621102cad 210 //
oprospero 2:bd1621102cad 211 //}
oprospero 0:26a151d2c6db 212
oprospero 0:26a151d2c6db 213
oprospero 0:26a151d2c6db 214 /********************** bool isSignalGood() ******************************/
oprospero 0:26a151d2c6db 215 /* For future use */
oprospero 0:26a151d2c6db 216 /*************************************************************************/
oprospero 0:26a151d2c6db 217 bool com::isSignalGood()
oprospero 0:26a151d2c6db 218 {
oprospero 0:26a151d2c6db 219 signalStrength = rssi.dutycycle();
oprospero 0:26a151d2c6db 220 if (signalStrength > RSSI_THRES) return true;
oprospero 0:26a151d2c6db 221 else return false;
oprospero 0:26a151d2c6db 222 }
oprospero 0:26a151d2c6db 223
oprospero 2:bd1621102cad 224 void com::setAPImode(bool mode)
oprospero 2:bd1621102cad 225 {
oprospero 2:bd1621102cad 226 api_mode = mode;
oprospero 2:bd1621102cad 227 }
oprospero 2:bd1621102cad 228