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@4:f8e953201251, 2014-04-22 (annotated)

Committer:
oprospero
Date:
Tue Apr 22 05:43:33 2014 +0000
Revision:
4:f8e953201251
Parent:
2:bd1621102cad
Child:
5:7cdf299ea7a4
move acknowledge out of RX interrupt into loop

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