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342 lines
9.2 KiB
C
342 lines
9.2 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilotModules OpenPilot Modules
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* @{
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* @addtogroup GSPModule GPS Module
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* @brief Process GPS information (UBX binary format)
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* @{
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*
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* @file UBX.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief GPS module, handles GPS and NMEA stream
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* @see The GNU Public License (GPL) Version 3
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*
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*****************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "openpilot.h"
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#include "pios.h"
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#if defined(PIOS_INCLUDE_GPS_UBX_PARSER)
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#include "UBX.h"
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#include "GPS.h"
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// parse incoming character stream for messages in UBX binary format
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int parse_ubx_stream (uint8_t c, char *gps_rx_buffer, GPSPositionData *GpsData, struct GPS_RX_STATS *gpsRxStats)
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{
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enum proto_states {
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START,
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UBX_SY2,
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UBX_CLASS,
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UBX_ID,
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UBX_LEN1,
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UBX_LEN2,
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UBX_PAYLOAD,
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UBX_CHK1,
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UBX_CHK2,
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FINISHED
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};
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static enum proto_states proto_state = START;
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static uint8_t rx_count = 0;
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struct UBXPacket *ubx = (struct UBXPacket *)gps_rx_buffer;
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switch (proto_state) {
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case START: // detect protocol
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if (c == UBX_SYNC1) // first UBX sync char found
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proto_state = UBX_SY2;
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break;
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case UBX_SY2:
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if (c == UBX_SYNC2) // second UBX sync char found
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proto_state = UBX_CLASS;
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else
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proto_state = START; // reset state
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break;
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case UBX_CLASS:
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ubx->header.class = c;
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proto_state = UBX_ID;
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break;
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case UBX_ID:
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ubx->header.id = c;
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proto_state = UBX_LEN1;
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break;
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case UBX_LEN1:
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ubx->header.len = c;
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proto_state = UBX_LEN2;
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break;
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case UBX_LEN2:
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ubx->header.len += (c << 8);
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if (ubx->header.len > sizeof(UBXPayload)) {
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gpsRxStats->gpsRxOverflow++;
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proto_state = START;
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} else {
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rx_count = 0;
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proto_state = UBX_PAYLOAD;
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}
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break;
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case UBX_PAYLOAD:
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if (rx_count < ubx->header.len) {
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ubx->payload.payload[rx_count] = c;
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if (++rx_count == ubx->header.len)
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proto_state = UBX_CHK1;
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} else {
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gpsRxStats->gpsRxOverflow++;
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proto_state = START;
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}
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break;
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case UBX_CHK1:
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ubx->header.ck_a = c;
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proto_state = UBX_CHK2;
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break;
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case UBX_CHK2:
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ubx->header.ck_b = c;
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if (checksum_ubx_message(ubx)) { // message complete and valid
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parse_ubx_message(ubx, GpsData);
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proto_state = FINISHED;
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} else {
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gpsRxStats->gpsRxChkSumError++;
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proto_state = START;
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}
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break;
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default: break;
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}
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if (proto_state == START)
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return PARSER_ERROR; // parser couldn't use this byte
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else if (proto_state == FINISHED) {
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gpsRxStats->gpsRxReceived++;
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proto_state = START;
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return PARSER_COMPLETE; // message complete & processed
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}
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return PARSER_INCOMPLETE; // message not (yet) complete
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}
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// Keep track of various GPS messages needed to make up a single UAVO update
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// time-of-week timestamp is used to correlate matching messages
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#define POSLLH_RECEIVED (1 << 0)
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#define STATUS_RECEIVED (1 << 1)
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#define DOP_RECEIVED (1 << 2)
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#define VELNED_RECEIVED (1 << 3)
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#define SOL_RECEIVED (1 << 4)
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#define ALL_RECEIVED (SOL_RECEIVED | VELNED_RECEIVED | DOP_RECEIVED | POSLLH_RECEIVED)
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#define NONE_RECEIVED 0
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static struct msgtracker{
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uint32_t currentTOW; // TOW of the message set currently in progress
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uint8_t msg_received; // keep track of received message types
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} msgtracker;
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// Check if a message belongs to the current data set and register it as 'received'
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bool check_msgtracker (uint32_t tow, uint8_t msg_flag)
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{
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if (tow > msgtracker.currentTOW ? true // start of a new message set
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: (msgtracker.currentTOW - tow > 6*24*3600*1000)) { // 6 days, TOW wrap around occured
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msgtracker.currentTOW = tow;
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msgtracker.msg_received = NONE_RECEIVED;
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} else if (tow < msgtracker.currentTOW) // message outdated (don't process)
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return false;
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msgtracker.msg_received |= msg_flag; // register reception of this msg type
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return true;
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}
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bool checksum_ubx_message (struct UBXPacket *ubx)
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{
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int i;
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uint8_t ck_a, ck_b;
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ck_a = ubx->header.class;
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ck_b = ck_a;
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ck_a += ubx->header.id;
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ck_b += ck_a;
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ck_a += ubx->header.len & 0xff;
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ck_b += ck_a;
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ck_a += ubx->header.len >> 8;
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ck_b += ck_a;
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for (i = 0; i < ubx->header.len; i++) {
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ck_a += ubx->payload.payload[i];
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ck_b += ck_a;
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}
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if (ubx->header.ck_a == ck_a &&
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ubx->header.ck_b == ck_b)
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return true;
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else
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return false;
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}
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void parse_ubx_nav_posllh (struct UBX_NAV_POSLLH *posllh, GPSPositionData *GpsPosition)
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{
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if (check_msgtracker(posllh->iTOW, POSLLH_RECEIVED)) {
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if (GpsPosition->Status != GPSPOSITION_STATUS_NOFIX) {
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GpsPosition->Altitude = (float)posllh->hMSL*0.001f;
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GpsPosition->GeoidSeparation = (float)(posllh->height - posllh->hMSL)*0.001f;
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GpsPosition->Latitude = posllh->lat;
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GpsPosition->Longitude = posllh->lon;
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}
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}
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}
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void parse_ubx_nav_sol (struct UBX_NAV_SOL *sol, GPSPositionData *GpsPosition)
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{
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if (check_msgtracker(sol->iTOW, SOL_RECEIVED)) {
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GpsPosition->Satellites = sol->numSV;
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if (sol->flags & STATUS_FLAGS_GPSFIX_OK) {
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switch (sol->gpsFix) {
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case STATUS_GPSFIX_2DFIX:
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GpsPosition->Status = GPSPOSITION_STATUS_FIX2D;
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break;
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case STATUS_GPSFIX_3DFIX:
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GpsPosition->Status = GPSPOSITION_STATUS_FIX3D;
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break;
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default: GpsPosition->Status = GPSPOSITION_STATUS_NOFIX;
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}
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}
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else // fix is not valid so we make sure to treat is as NOFIX
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GpsPosition->Status = GPSPOSITION_STATUS_NOFIX;
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}
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}
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void parse_ubx_nav_dop (struct UBX_NAV_DOP *dop, GPSPositionData *GpsPosition)
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{
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if (check_msgtracker(dop->iTOW, DOP_RECEIVED)) {
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GpsPosition->HDOP = (float)dop->hDOP * 0.01f;
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GpsPosition->VDOP = (float)dop->vDOP * 0.01f;
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GpsPosition->PDOP = (float)dop->pDOP * 0.01f;
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}
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}
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void parse_ubx_nav_velned (struct UBX_NAV_VELNED *velned, GPSPositionData *GpsPosition)
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{
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GPSVelocityData GpsVelocity;
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if (check_msgtracker(velned->iTOW, VELNED_RECEIVED)) {
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if (GpsPosition->Status != GPSPOSITION_STATUS_NOFIX) {
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GpsVelocity.North = (float)velned->velN/100.0f;
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GpsVelocity.East = (float)velned->velE/100.0f;
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GpsVelocity.Down = (float)velned->velD/100.0f;
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GPSVelocitySet(&GpsVelocity);
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GpsPosition->Groundspeed = (float)velned->gSpeed * 0.01f;
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GpsPosition->Heading = (float)velned->heading * 1.0e-5f;
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}
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}
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}
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#if !defined(PIOS_GPS_MINIMAL)
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void parse_ubx_nav_timeutc (struct UBX_NAV_TIMEUTC *timeutc)
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{
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if (!(timeutc->valid & TIMEUTC_VALIDUTC))
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return;
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GPSTimeData GpsTime;
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GpsTime.Year = timeutc->year;
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GpsTime.Month = timeutc->month;
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GpsTime.Day = timeutc->day;
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GpsTime.Hour = timeutc->hour;
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GpsTime.Minute = timeutc->min;
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GpsTime.Second = timeutc->sec;
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GPSTimeSet(&GpsTime);
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}
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#endif
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#if !defined(PIOS_GPS_MINIMAL)
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void parse_ubx_nav_svinfo (struct UBX_NAV_SVINFO *svinfo)
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{
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uint8_t chan;
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GPSSatellitesData svdata;
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svdata.SatsInView = 0;
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for (chan = 0; chan < svinfo->numCh; chan++) {
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if (svdata.SatsInView < GPSSATELLITES_PRN_NUMELEM) {
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svdata.Azimuth[svdata.SatsInView] = (float)svinfo->sv[chan].azim;
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svdata.Elevation[svdata.SatsInView] = (float)svinfo->sv[chan].elev;
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svdata.PRN[svdata.SatsInView] = svinfo->sv[chan].svid;
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svdata.SNR[svdata.SatsInView] = svinfo->sv[chan].cno;
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svdata.SatsInView++;
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}
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}
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// fill remaining slots (if any)
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for (chan = svdata.SatsInView; chan < GPSSATELLITES_PRN_NUMELEM; chan++) {
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svdata.Azimuth[chan] = (float)0.0f;
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svdata.Elevation[chan] = (float)0.0f;
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svdata.PRN[chan] = 0;
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svdata.SNR[chan] = 0;
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}
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GPSSatellitesSet(&svdata);
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}
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#endif
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// UBX message parser
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// returns UAVObjectID if a UAVObject structure is ready for further processing
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uint32_t parse_ubx_message (struct UBXPacket *ubx, GPSPositionData *GpsPosition)
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{
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uint32_t id = 0;
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switch (ubx->header.class) {
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case UBX_CLASS_NAV:
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switch (ubx->header.id) {
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case UBX_ID_POSLLH:
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parse_ubx_nav_posllh (&ubx->payload.nav_posllh, GpsPosition);
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break;
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case UBX_ID_DOP:
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parse_ubx_nav_dop (&ubx->payload.nav_dop, GpsPosition);
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break;
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case UBX_ID_SOL:
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parse_ubx_nav_sol (&ubx->payload.nav_sol, GpsPosition);
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break;
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case UBX_ID_VELNED:
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parse_ubx_nav_velned (&ubx->payload.nav_velned, GpsPosition);
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break;
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#if !defined(PIOS_GPS_MINIMAL)
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case UBX_ID_TIMEUTC:
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parse_ubx_nav_timeutc (&ubx->payload.nav_timeutc);
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break;
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case UBX_ID_SVINFO:
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parse_ubx_nav_svinfo (&ubx->payload.nav_svinfo);
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break;
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#endif
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}
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break;
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}
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if (msgtracker.msg_received == ALL_RECEIVED) {
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GPSPositionSet(GpsPosition);
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msgtracker.msg_received = NONE_RECEIVED;
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id = GPSPOSITION_OBJID;
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}
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return id;
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}
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#endif // PIOS_INCLUDE_GPS_UBX_PARSER
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