PCMessaging.h

00001 //these are defines for the messages that are sent from the PC across the USB
00002 //these messages produce reactions on the mbed
00003 //currently there is only a single message -- the trigger command
00004 const unsigned char  FIRE_TRIGGER_MSG   = 1;
00005 
00006 const unsigned short msgBuffSize = 28;
00007 char messageBuffer[msgBuffSize+1];  //the +1 allows for a null-terminated string
00008 
00009 //flags to control the mbed actions (in main) in response to the PC command
00010 bool fireTrigger    = false;
00011 
00012 unsigned char CR = 0x0d;                //ASCII Carriage Return
00013 unsigned char LF = 0x0a;                //ASCII Line Feed
00014 
00015 int totalNumChars = 0;
00016 
00017 bool validMessage = false;
00018 
00019 /*
00020 void readFromPC()
00021 {
00022     //read all available PC serial bytes and test the sequence for a command string
00023     if (toPC.readable()) 
00024     {   loopsThroughPCreadable++;  //reset to zero when we detect a valid message
00025         //wait_ms(5);
00026     }
00027     while (toPC.readable()) 
00028     {
00029         ///////////////////////////////////////////////////////////////////////////////////
00030         //PC-to-mbed and mbed-to-PC message format
00031         //   1) preamble:            "mbedmessage "   (note the space)
00032         //   2) messageType          "trig "          (note the space
00033         //   3) 10-char dataValue    "0000000000"     (ASCI integer representation
00034         //0123456789012345678901234567890123456789
00035         //mbedmessage trig 0000000000 CR/LF
00036         ///////////////////////////////////////////////////////////////////////////////////
00037         
00038         // Read in next character
00039         // we get through the main loop at > 500,000 times a sec
00040         unsigned char inChar = 0;
00041         inChar = toPC.getc();  //read char from the USB serial link to the PC
00042         
00043         totalNumChars++;
00044         
00045         //slide all the characters back by one place -- oldest char in the buffer gets discarded
00046         for (int i=0; i<(msgBuffSize-1); i++) messageBuffer[i] = messageBuffer[i+1];
00047         //now fill in the last entry to the buffer with the most recent received char
00048         messageBuffer[msgBuffSize-1] = inChar;
00049         
00050         //locate the proper message signature in the saved buffer:  "mbedmessage "
00051         if      (messageBuffer[0]  != 'm') continue;
00052         else if( messageBuffer[1]  != 'b') continue;
00053         else if( messageBuffer[2]  != 'e') continue;
00054         else if( messageBuffer[3]  != 'd') continue;
00055         else if( messageBuffer[4]  != 'm') continue;
00056         else if( messageBuffer[5]  != 'e') continue;
00057         else if( messageBuffer[6]  != 's') continue;
00058         else if( messageBuffer[7]  != 's') continue;
00059         else if( messageBuffer[8]  != 'a') continue;       
00060         else if( messageBuffer[9]  != 'g') continue;  
00061         else if( messageBuffer[10] != 'e') continue;  
00062         else if( messageBuffer[11] != ' ') continue; 
00063         //else if( messageBuffer[28] != CR) return;  
00064         //else if( messageBuffer[29] != LF) return;
00065         
00066         //from testing: this always activates on inChar multiple of 28
00067         //if ( inChar == 0x0a ) toPC.printf("%d  LF received:   %s\n",totalNumChars, messageBuffer);
00068         
00069         //if we get here. we have the proper signature of an incoming message
00070         //now test for the message types
00071         
00072         //why do we do this??
00073         //messageBuffer[msgBuffSize]= '/0'; //make the message buffer a null-terminated ASCII string
00074         
00075         //if (toPC.writeable()) toPC.printf(messageBuffer);    
00076             
00077         if (    messageBuffer[12] == 't' && 
00078                 messageBuffer[13] == 'r' && 
00079                 messageBuffer[14] == 'i' && 
00080                 messageBuffer[15] == 'g'    )
00081         {
00082             //we have detected a trigger command message: "trig"  
00083             //send back a response to this message
00084             if (toPC.writeable())
00085             {
00086                  toPC.printf("FromMbed  %s \n", messageBuffer);
00087                  toPC.printf("FromMbed   %d  %d  \n", loopsThroughPCreadable, totalNumChars);
00088             }
00089             fireTrigger = true;
00090             loopsThroughPCreadable = 0;
00091         }
00092         
00093     }  //end pc.readable
00094 };
00095 */
00096 
00097 void readFromPC()
00098 {
00099         
00100     //if there is no chars to read -- just return;
00101     if (!toPC.readable()) return;
00102     
00103     totalNumChars = 0;
00104     
00105     if (toPC.writeable())
00106     {
00107         toPC.printf("FromMbed  testing for Trigger \n");
00108     }
00109     
00110     bool timeOutInRead = false;
00111 
00112     timeInMessageRead.reset();
00113     
00114     while (totalNumChars < 16) 
00115     {
00116         ///////////////////////////////////////////////////////////////////////////////////
00117         //PC-to-mbed and mbed-to-PC message format
00118         //   1) preamble:            "mbedmessage "   (note the space)
00119         //   2) messageType          "trig "          (note the space
00120         //   3) 10-char dataValue    "0000000000"     (ASCI integer representation
00121         //0123456789012345678901234567890123456789
00122         //mbedmessage trig 0000000000 CR/LF
00123         ///////////////////////////////////////////////////////////////////////////////////
00124         
00125         // we get through the main loop at > 500,000 times a sec
00126 
00127         if ( toPC.readable() )
00128         { 
00129             messageBuffer[totalNumChars] = toPC.getc();
00130             totalNumChars++;
00131         }
00132         
00133         if (timeInMessageRead.read_us() > 500)
00134         {
00135              timeOutInRead = true;
00136              break;
00137         }
00138     }
00139     
00140     messageBuffer[28] = '\0';  //make a null-terminated string
00141        
00142     if (timeOutInRead)
00143     {
00144         if (toPC.writeable())
00145         {
00146             toPC.printf("FromMbed TimeOut %s \n", messageBuffer);
00147         }
00148     }
00149     
00150  
00151         
00152     if      (messageBuffer[0]  == 'm' &&
00153              messageBuffer[1]  == 'b' &&
00154              messageBuffer[2]  == 'e' &&
00155              messageBuffer[3]  == 'd' &&
00156              messageBuffer[4]  == 'm' &&
00157              messageBuffer[5]  == 'e' &&
00158              messageBuffer[6]  == 's' &&
00159              messageBuffer[7]  == 's' &&
00160              messageBuffer[8]  == 'a' &&       
00161              messageBuffer[9]  == 'g' &&  
00162              messageBuffer[10] == 'e' &&  
00163              messageBuffer[11] == ' ' && 
00164              messageBuffer[12] == 't' && 
00165              messageBuffer[13] == 'r' && 
00166              messageBuffer[14] == 'i' && 
00167              messageBuffer[15] == 'g'    )
00168         {
00169 
00170             
00171             //we have detected a trigger command message: "trig"  
00172             //send back a response to this message
00173             if (toPC.writeable())
00174             {
00175                 toPC.printf("FromMbed  %s %d\n", messageBuffer, timeInMessageRead.read_us());
00176             }
00177             
00178             for (int i=0; i<=msgBuffSize; i++) messageBuffer[i] = 0;
00179             fireTrigger = true;
00180         }
00181         else
00182         {
00183             toPC.printf("FromMbed badMsg  %s \n", messageBuffer);
00184             for (int i=0; i<=msgBuffSize; i++) messageBuffer[i] = 0;
00185         }
00186 };
00187