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• WIO Overview | WIO Setup | WIO Control | User Bitmaps | WIO Firmware
• WIO RASCII | WIO CAN Protocol
  • CAN ASCII Framing

Communication over serial or TCP/IP the ASCII framing is used.

:XhhhhhhhhNd0d1d2d3d4d5d6d7;\n

:X       -> X=extended S=short (start of CAN Frame)
hhhhhhhh -> ID (4 bytes extended and 2 bytes short)
N        -> N=normal R=RTR
d0-d7    -> Data (Zero to eight data bytes)
;        -> end of frame (semi colon)
\n       -> linefeed

The DLC is calculated by the number of data bytes following the type 'N' or 'R'.
Short IDs are not used in the RCAN protocol.

:X04070101N112233445566;

int rcan_makeExtASCIIFrame(char* frame, int prio, byte* databytes, int datalen, long id, Boolean linefeed ) {
  int i = 0;
 
  StrOp.fmtb( (char*)(frame+1), ":X%02X%02X%02X%02XN;%c",
      (id >> 24) & 0xFF, (id >> 16) & 0xFF, (id >> 8) & 0xFF, id & 0xFF, linefeed?'\n':'\0' );
 
  if( datalen > 0 ) {
    for( i = 0; i < datalen; i++ ) {
      // :X00080004N
      StrOp.fmtb( (char*)(frame+1+11+i*2), "%02X;%c", databytes[i], linefeed?'\n':'\0' );
    }
  }
 
  frame[0] = StrOp.len((char*)(frame+1));
 
  return frame[0];
}

static char hexb[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, 0, 10, 11, 12, 13, 14, 15};
void rcan_ASCIIFrame2CANFrame(const char* frame, iCANFrame canFrame) {
  Boolean ok = True;
  int offset = 0;
  int idh    = 0;
  int idl    = 0;
  int edh    = 0;
  int edl    = 0;
  int opc    = 0;
  int i      = 0;
  int len    = StrOp.len(frame);
 
  canFrame->flags = 0;
 
  if(frame[1] == 'X') {
    offset = 4;
    canFrame->flags = CANFLAG_EXTENDED;
    edh = mbus_HEXA2Byte(frame + 2);
    edl = mbus_HEXA2Byte(frame + 4);
    idh = mbus_HEXA2Byte(frame + 6);
    idl = mbus_HEXA2Byte(frame + 8);
  }
  else {
    idh = mbus_HEXA2Byte(frame + 2);
    idl = mbus_HEXA2Byte(frame + 4);
  }
 
  canFrame->id = (edh << 24 ) + (edl << 16 ) + (idh << 8 ) + idl;
 
  // Lookup ';' to determine the dlc.
  canFrame->dlc = 0;
  for( i = 0; i < len; i++ ) {
    if( frame[7+offset+ i*2 + 2] == ';' ) {
      canFrame->dlc = i + 1;
      break;
    }
  }
 
  for( i = 0; i < canFrame->dlc; i++ ) {
    canFrame->data[i] = (hexb[frame[7 + offset + 2 * i] - 0x30] << 4) + hexb[frame[7 + offset + 2 * i + 1] - 0x30];
  }
 
}