#ifndef atmel_hdlc_h #define atmel_hdlc_h /// HDLC ///////////////////////////////////////////////////////// /* a protocol for serial communication featuring frames, checksum and auto-escaping of characters. datasheet: http://tools.ietf.org/html/rfc1662 send: Serial.begin(57600); // open serialport hdlc.frameOpen(); // framestart hdlc.frameWrite(byte data); //repeat as often as you want hdlc.frameClose(); // frame-ending (&checksum) and flush receive: uint8_t incoming_msg[80]; if (uint8_t msg_size = hdlc.poll()) { for (uint8_t ivar=0; ivar < size_msg; ++ivar ) { incoming_msg[ivar] = hdlc.getMsg(ivar); }; }; hdlc.clearMsg(); */ class HDLC { private: static constexpr uint8_t HDLC_FLAG = (0x7e); static constexpr uint8_t HDLC_ESCAPE = (0x7d); static constexpr uint8_t HDLC_FLAG_ESC = (0x5e); static constexpr uint8_t HDLC_ESCAPE_ESC = (0x5d); static constexpr uint8_t HDLC_ESCAPE_MASK = (0x20); static constexpr uint16_t HDLC_CRCINIT = (0xffff); static constexpr uint16_t HDLC_CRCGOOD = (0xf0b8); static constexpr uint16_t HDLC_MAX_FRAME_LENGTH = (128); static constexpr uint16_t HDLC_INPUT_BUFFER_SIZE = (HDLC_MAX_FRAME_LENGTH); static constexpr uint16_t hdlc_fcstab[256] = { 0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf, 0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7, 0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e, 0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876, 0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd, 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5, 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c, 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974, 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb, 0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3, 0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a, 0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72, 0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9, 0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1, 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738, 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70, 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7, 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff, 0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036, 0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e, 0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5, 0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd, 0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134, 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c, 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3, 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb, 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232, 0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a, 0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1, 0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9, 0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330, 0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78 }; inline uint16_t crcIteration(const uint16_t crc, const uint8_t _b) { return (crc >> 8) ^ hdlc_fcstab[(crc ^ _b) & 0xff]; }; uint16_t crc16; uint8_t msg_now, msg_received, msg[HDLC_INPUT_BUFFER_SIZE]; public: HDLC(void): crc16(0), msg_now(0), msg_received(0) { for (uint8_t loopvar = 0; loopvar < HDLC_INPUT_BUFFER_SIZE; ++loopvar) { msg[loopvar] = 0; }; }; // TODO: not ideal, but ok for now void frameOpen(void) { Serial.write(HDLC_FLAG); crc16 = HDLC_CRCINIT; }; void frameWrite(const uint8_t _b) { crc16 = crcIteration(crc16,_b); uint8_t bw; if (_b == HDLC_FLAG) { Serial.write(HDLC_ESCAPE); bw = HDLC_FLAG_ESC; } else if (_b == HDLC_ESCAPE) { Serial.write(HDLC_ESCAPE); bw = HDLC_ESCAPE_ESC; } else bw = _b; Serial.write(bw); }; uint16_t frameClose(void) { uint16_t _crc = ~crc16; frameWrite((_crc>>0)& 0xFF); frameWrite((_crc>>8)& 0xFF); Serial.write(HDLC_FLAG); Serial.flush(); }; uint8_t poll() { if (msg_received < 3) // shortcut, nothing to analyze { while (Serial.available()) { uint8_t _b = uint8_t(Serial.read()); if (msg_received == 0) { if (_b==HDLC_FLAG) msg_received = 1; if (!Serial.available()) delay(1); continue; }; if ((msg_received == 2)&&(_b==HDLC_FLAG)) // message complete { msg_received = 3; break; }; if (msg_received == 1) { if (_b==HDLC_FLAG) continue; // startflag found, do nothing else msg_received = 2; // >1 other character after specialflag found, normal message buffering }; if (msg_received == 2) { if (_b == HDLC_ESCAPE) { uint8_t wstop = 0; while(!Serial.available()) { //ps.sleep ( 0 ); delay(1); if (wstop++ > 10) break; }; _b = uint8_t(Serial.read()); if (_b == HDLC_FLAG_ESC) _b = HDLC_FLAG; if (_b == HDLC_ESCAPE_ESC) _b = HDLC_ESCAPE; }; msg[msg_now] = _b; msg_now ++; }; if (!Serial.available()) delay(1); //ps.sleep ( 0 ); }; }; if (msg_received == 3) { msg_now -= 2; // cut away sync-bytes uint16_t crcT = HDLC_CRCINIT; for (uint8_t ivar = 0; ivar < msg_now; ++ivar) { crcT = crcIteration(crcT,msg[ivar]); }; crcT = ~crcT; uint16_t crcM = msg[msg_now] | (msg[msg_now+1]<<8); if (crcM != crcT) { clearMsg(); return 0; }; msg_received = 4; return msg_now; }; if (msg_received > 2) return msg_now; else return 0; }; uint8_t getMsg(const uint8_t position) { uint8_t _b; if (position > (HDLC_INPUT_BUFFER_SIZE - 1)) _b = 0; else _b = msg[position]; return _b; }; void clearMsg() { msg_received = 0; msg_now = 0; }; }; constexpr uint16_t HDLC::hdlc_fcstab[]; // definition - workaround HDLC hdlc; #endif