/** * http://ad7zj.net/kd7lmo/aprsbeacon_code.html * * @mainpage Pico Beacon * * @section overview_sec Overview * * The Pico Beacon is an APRS based tracking beacon that operates in the UHF 420-450MHz band. The device utilizes a * Microchip PIC 18F2525 embedded controller, Motorola M12+ GPS engine, and Analog Devices AD9954 DDS. The device is capable * of generating a 1200bps A-FSK and 9600 bps FSK AX.25 compliant APRS (Automatic Position Reporting System) message. * * @section history_sec Revision History * * @subsection v305 V3.05 * 23 Dec 2006, Change include; (1) change printf format width to conform to ANSI standard when new CCS 4.xx compiler released. * * * @subsection v304 V3.04 * 10 Jan 2006, Change include; (1) added amplitude control to engineering mode, * (2) corrected number of bytes reported in log, * (3) add engineering command to set high rate position reports (5 seconds), and * (4) corrected size of LOG_COORD block when searching for end of log. * * @subsection v303 V3.03 * 15 Sep 2005, Change include; (1) removed AD9954 setting SDIO as input pin, * (2) additional comments and Doxygen tags, * (3) integration and test code calculates DDS FTW, * (4) swapped bus and reference analog input ports (hardware change), * (5) added message that indicates we are reading flash log and reports length, * (6) report bus voltage in 10mV steps, and * (7) change log type enumerated values to XORed nibbles for error detection. * * * @subsection v302 V3.02 * 6 Apr 2005, Change include; (1) corrected tracked satellite count in NMEA-0183 $GPGGA message, * (2) Doxygen documentation clean up and additions, and * (3) added integration and test code to baseline. * * * @subsection v301 V3.01 * 13 Jan 2005, Renamed project and files to Pico Beacon. * * * @subsection v300 V3.00 * 15 Nov 2004, Change include; (1) Micro Beacon extreme hardware changes including integral transmitter, * (2) PIC18F2525 processor, * (3) AD9954 DDS support functions, * (4) added comments and formatting for doxygen, * (5) process GPS data with native Motorola protocol, * (6) generate plain text $GPGGA and $GPRMC messages, * (7) power down GPS 5 hours after lock, * (8) added flight data recorder, and * (9) added diagnostics terminal mode. * * * @subsection v201 V2.01 * 30 Jan 2004, Change include; (1) General clean up of in-line documentation, and * (2) changed temperature resolution to 0.1 degrees F. * * * @subsection v200 V2.00 * 26 Oct 2002, Change include; (1) Micro Beacon II hardware changes including PIC18F252 processor, * (2) serial EEPROM, * (3) GPS power control, * (4) additional ADC input, and * (5) LM60 temperature sensor. * * * @subsection v101 V1.01 * 5 Dec 2001, Change include; (1) Changed startup message, and * (2) applied SEPARATE pragma to several methods for memory usage. * * * @subsection v100 V1.00 * 25 Sep 2001, Initial release. Flew ANSR-3 and ANSR-4. * * * * @section copyright_sec Copyright * * Copyright (c) 2001-2009 Michael Gray, KD7LMO * * * @section gpl_sec GNU General Public License * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * * * * @section design Design Details * * Provides design details on a variety of the components that make up the Pico Beacon. * * @subpage power */ /** * @page power Power Consumption * * Measured DC power consumption. * * 3VDC prime power current * * 7mA Held in reset * 18mA Processor running, all I/O off * 110mA GPS running * 120mA GPS running w/antenna * 250mA DDS running and GPS w/antenna * 420mA DDS running, GPS w/antenna, and PA chain on with no RF * 900mA Transmit * */ #ifndef AO_APRS_TEST #include #endif #include // Public methods, constants, and data structures for each class. static void timeInit(void); static void tncInit(void); static void tnc1200TimerTick(void); /** @} */ /** * @defgroup sys System Library Functions * * Generic system functions similiar to the run-time C library. * * @{ */ /** * Calculate the CRC-16 CCITT of buffer that is length bytes long. * The crc parameter allow the calculation on the CRC on multiple buffers. * * @param buffer Pointer to data buffer. * @param length number of bytes in data buffer * @param crc starting value * * @return CRC-16 of buffer[0 .. length] */ static uint16_t sysCRC16(const uint8_t *buffer, uint8_t length, uint16_t crc) { uint8_t i, bit, value; for (i = 0; i < length; ++i) { value = buffer[i]; for (bit = 0; bit < 8; ++bit) { crc ^= (value & 0x01); crc = ( crc & 0x01 ) ? ( crc >> 1 ) ^ 0x8408 : ( crc >> 1 ); value = value >> 1; } // END for } // END for return crc ^ 0xffff; } /** @} */ /** * @defgroup rtc Real Time Interrupt tick * * Manage the built-in real time interrupt. The interrupt clock PRI is 104uS (9600 bps). * * @{ */ /// 16-bit NCO where the upper 8-bits are used to index into the frequency generation table. static uint16_t timeNCO; /// Audio tone NCO update step (phase). static uint16_t timeNCOFreq; /** * Initialize the real-time clock. */ static void timeInit() { timeNCO = 0x00; timeNCOFreq = 0x2000; } /** @} */ /** * @defgroup tnc TNC (Terminal Node Controller) * * Functions that provide a subset of the TNC functions. * * @{ */ /// The number of start flag bytes to send before the packet message. (360bits * 1200bps = 300mS) #define TNC_TX_DELAY 45 /// The size of the TNC output buffer. #define TNC_BUFFER_SIZE 40 /// States that define the current mode of the 1200 bps (A-FSK) state machine. typedef enum { /// Stand by state ready to accept new message. TNC_TX_READY, /// 0x7E bit stream pattern used to define start of APRS message. TNC_TX_SYNC, /// Transmit the AX.25 header that contains the source/destination call signs, APRS path, and flags. TNC_TX_HEADER, /// Transmit the message data. TNC_TX_DATA, /// Transmit the end flag sequence. TNC_TX_END } TNC_TX_1200BPS_STATE; /// AX.25 compliant packet header that contains destination, station call sign, and path. /// 0x76 for SSID-11, 0x78 for SSID-12 static uint8_t TNC_AX25_HEADER[] = { 'A' << 1, 'P' << 1, 'A' << 1, 'M' << 1, ' ' << 1, ' ' << 1, 0x60, \ 'N' << 1, '0' << 1, 'C' << 1, 'A' << 1, 'L' << 1, 'L' << 1, 0x78, \ 'W' << 1, 'I' << 1, 'D' << 1, 'E' << 1, '2' << 1, ' ' << 1, 0x65, \ 0x03, 0xf0 }; #define TNC_CALLSIGN_OFF 7 #define TNC_CALLSIGN_LEN 6 static void tncSetCallsign(void) { #ifndef AO_APRS_TEST uint8_t i; for (i = 0; i < TNC_CALLSIGN_LEN; i++) { if (!ao_config.callsign[i]) break; TNC_AX25_HEADER[TNC_CALLSIGN_OFF + i] = ao_config.callsign[i] << 1; } for (; i < TNC_CALLSIGN_LEN; i++) TNC_AX25_HEADER[TNC_CALLSIGN_OFF + i] = ' ' << 1; #endif } /// The next bit to transmit. static uint8_t tncTxBit; /// Current mode of the 1200 bps state machine. static TNC_TX_1200BPS_STATE tncMode; /// Counter for each bit (0 - 7) that we are going to transmit. static uint8_t tncBitCount; /// A shift register that holds the data byte as we bit shift it for transmit. static uint8_t tncShift; /// Index into the APRS header and data array for each byte as we transmit it. static uint8_t tncIndex; /// The number of bytes in the message portion of the AX.25 message. static uint8_t tncLength; /// A copy of the last 5 bits we've transmitted to determine if we need to bit stuff on the next bit. static uint8_t tncBitStuff; /// Buffer to hold the message portion of the AX.25 packet as we prepare it. static uint8_t tncBuffer[TNC_BUFFER_SIZE]; /** * Initialize the TNC internal variables. */ static void tncInit() { tncTxBit = 0; tncMode = TNC_TX_READY; } /** * Method that is called every 833uS to transmit the 1200bps A-FSK data stream. * The provides the pre and postamble as well as the bit stuffed data stream. */ static void tnc1200TimerTick() { // Set the A-FSK frequency. if (tncTxBit == 0x00) timeNCOFreq = 0x2000; else timeNCOFreq = 0x3aab; switch (tncMode) { case TNC_TX_READY: // Generate a test signal alteranting between high and low tones. tncTxBit = (tncTxBit == 0 ? 1 : 0); break; case TNC_TX_SYNC: // The variable tncShift contains the lastest data byte. // NRZI enocde the data stream. if ((tncShift & 0x01) == 0x00) { if (tncTxBit == 0) tncTxBit = 1; else tncTxBit = 0; } // When the flag is done, determine if we need to send more or data. if (++tncBitCount == 8) { tncBitCount = 0; tncShift = 0x7e; // Once we transmit x mS of flags, send the data. // txDelay bytes * 8 bits/byte * 833uS/bit = x mS if (++tncIndex == TNC_TX_DELAY) { tncIndex = 0; tncShift = TNC_AX25_HEADER[0]; tncBitStuff = 0; tncMode = TNC_TX_HEADER; } // END if } else tncShift = tncShift >> 1; break; case TNC_TX_HEADER: // Determine if we have sent 5 ones in a row, if we have send a zero. if (tncBitStuff == 0x1f) { if (tncTxBit == 0) tncTxBit = 1; else tncTxBit = 0; tncBitStuff = 0x00; return; } // END if // The variable tncShift contains the lastest data byte. // NRZI enocde the data stream. if ((tncShift & 0x01) == 0x00) { if (tncTxBit == 0) tncTxBit = 1; else tncTxBit = 0; } // Save the data stream so we can determine if bit stuffing is // required on the next bit time. tncBitStuff = ((tncBitStuff << 1) | (tncShift & 0x01)) & 0x1f; // If all the bits were shifted, get the next byte. if (++tncBitCount == 8) { tncBitCount = 0; // After the header is sent, then send the data. if (++tncIndex == sizeof(TNC_AX25_HEADER)) { tncIndex = 0; tncShift = tncBuffer[0]; tncMode = TNC_TX_DATA; } else tncShift = TNC_AX25_HEADER[tncIndex]; } else tncShift = tncShift >> 1; break; case TNC_TX_DATA: // Determine if we have sent 5 ones in a row, if we have send a zero. if (tncBitStuff == 0x1f) { if (tncTxBit == 0) tncTxBit = 1; else tncTxBit = 0; tncBitStuff = 0x00; return; } // END if // The variable tncShift contains the lastest data byte. // NRZI enocde the data stream. if ((tncShift & 0x01) == 0x00) { if (tncTxBit == 0) tncTxBit = 1; else tncTxBit = 0; } // Save the data stream so we can determine if bit stuffing is // required on the next bit time. tncBitStuff = ((tncBitStuff << 1) | (tncShift & 0x01)) & 0x1f; // If all the bits were shifted, get the next byte. if (++tncBitCount == 8) { tncBitCount = 0; // If everything was sent, transmit closing flags. if (++tncIndex == tncLength) { tncIndex = 0; tncShift = 0x7e; tncMode = TNC_TX_END; } else tncShift = tncBuffer[tncIndex]; } else tncShift = tncShift >> 1; break; case TNC_TX_END: // The variable tncShift contains the lastest data byte. // NRZI enocde the data stream. if ((tncShift & 0x01) == 0x00) { if (tncTxBit == 0) tncTxBit = 1; else tncTxBit = 0; } // If all the bits were shifted, get the next one. if (++tncBitCount == 8) { tncBitCount = 0; tncShift = 0x7e; // Transmit two closing flags. if (++tncIndex == 2) { tncMode = TNC_TX_READY; return; } // END if } else tncShift = tncShift >> 1; break; } // END switch } /** * Generate the plain text position packet. */ static int tncPositionPacket(void) { int32_t latitude = ao_gps_data.latitude; int32_t longitude = ao_gps_data.longitude; int32_t altitude = ao_gps_data.altitude; uint16_t lat_deg; uint16_t lon_deg; uint16_t lat_min; uint16_t lat_frac; uint16_t lon_min; uint16_t lon_frac; char lat_sign = 'N', lon_sign = 'E'; if (latitude < 0) { lat_sign = 'S'; latitude = -latitude; } if (longitude < 0) { lon_sign = 'W'; longitude = -longitude; } /* Round latitude and longitude by 0.005 minutes */ latitude = latitude + 833; if (latitude > 900000000) latitude = 900000000; longitude = longitude + 833; if (longitude > 1800000000) longitude = 1800000000; lat_deg = latitude / 10000000; latitude -= lat_deg * 10000000; latitude *= 60; lat_min = latitude / 10000000; latitude -= lat_min * 10000000; lat_frac = latitude / 100000; lon_deg = longitude / 10000000; longitude -= lon_deg * 10000000; longitude *= 60; lon_min = longitude / 10000000; longitude -= lon_min * 10000000; lon_frac = longitude / 100000; if (altitude < 0) altitude = 0; altitude = (altitude * (int32_t) 10000 + (3048/2)) / (int32_t) 3048; return sprintf ((char *) tncBuffer, "=%02u%02u.%02u%c\\%03u%02u.%02u%cO /A=%06u\015", lat_deg, lat_min, lat_frac, lat_sign, lon_deg, lon_min, lon_frac, lon_sign, altitude); } static int16_t tncFill(uint8_t *buf, int16_t len) { int16_t l = 0; uint8_t b; uint8_t bit; while (tncMode != TNC_TX_READY && l < len) { b = 0; for (bit = 0; bit < 8; bit++) { b = b << 1 | (timeNCO >> 15); timeNCO += timeNCOFreq; } *buf++ = b; l++; tnc1200TimerTick(); } if (tncMode == TNC_TX_READY) l = -l; return l; } /** * Prepare an AX.25 data packet. Each time this method is called, it automatically * rotates through 1 of 3 messages. * * @param dataMode enumerated type that specifies 1200bps A-FSK or 9600bps FSK */ void ao_aprs_send(void) { uint16_t crc; timeInit(); tncInit(); tncSetCallsign(); tncLength = tncPositionPacket(); // Calculate the CRC for the header and message. crc = sysCRC16(TNC_AX25_HEADER, sizeof(TNC_AX25_HEADER), 0xffff); crc = sysCRC16(tncBuffer, tncLength, crc ^ 0xffff); // Save the CRC in the message. tncBuffer[tncLength++] = crc & 0xff; tncBuffer[tncLength++] = (crc >> 8) & 0xff; // Prepare the variables that are used in the real-time clock interrupt. tncBitCount = 0; tncShift = 0x7e; tncTxBit = 0; tncIndex = 0; tncMode = TNC_TX_SYNC; ao_radio_send_lots(tncFill); } /** @} */