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LibrePilot/flight/Modules/GPS/GPS.c

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/**
******************************************************************************
* @addtogroup OpenPilotModules OpenPilot Modules
* @{
* @addtogroup GSPModule GPS Module
* @brief Process GPS information
* @{
*
* @file GPS.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
* @brief GPS module, handles GPS and NMEA stream
* @see The GNU Public License (GPL) Version 3
*
*****************************************************************************/
/*
* 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 3 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
*/
// ****************
#include "openpilot.h"
#include "GPS.h"
#include <stdbool.h>
#include "gpsposition.h"
#include "homelocation.h"
#include "gpstime.h"
#include "gpssatellites.h"
#include "gpsvelocity.h"
#include "WorldMagModel.h"
#include "CoordinateConversions.h"
#include "hwsettings.h"
#include "NMEA.h"
#include "UBX.h"
// ****************
// Private functions
static void gpsTask(void *parameters);
static void updateSettings();
#ifdef PIOS_GPS_SETS_HOMELOCATION
static void setHomeLocation(GPSPositionData * gpsData);
static float GravityAccel(float latitude, float longitude, float altitude);
#endif
// ****************
// Private constants
#define GPS_TIMEOUT_MS 500
#define NMEA_MAX_PACKET_LENGTH 96 // 82 max NMEA msg size plus 12 margin (because some vendors add custom crap) plus CR plus Linefeed
// same as in COM buffer
#ifdef PIOS_GPS_SETS_HOMELOCATION
// Unfortunately need a good size stack for the WMM calculation
#define STACK_SIZE_BYTES 800
#else
#define STACK_SIZE_BYTES 650
#endif
#define TASK_PRIORITY (tskIDLE_PRIORITY + 1)
// ****************
// Private variables
static uint32_t gpsPort;
static bool gpsEnabled = false;
static xTaskHandle gpsTaskHandle;
static char* gps_rx_buffer;
static uint32_t timeOfLastCommandMs;
static uint32_t timeOfLastUpdateMs;
static uint32_t numUpdates;
static uint32_t numChecksumErrors;
static uint32_t numParsingErrors;
// ****************
/**
* Initialise the gps module
* \return -1 if initialisation failed
* \return 0 on success
*/
int32_t GPSStart(void)
{
if (gpsEnabled) {
if (gpsPort) {
// Start gps task
xTaskCreate(gpsTask, (signed char *)"GPS", STACK_SIZE_BYTES/4, NULL, TASK_PRIORITY, &gpsTaskHandle);
TaskMonitorAdd(TASKINFO_RUNNING_GPS, gpsTaskHandle);
return 0;
}
AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_CRITICAL);
}
return -1;
}
/**
* Initialise the gps module
* \return -1 if initialisation failed
* \return 0 on success
*/
int32_t GPSInitialize(void)
{
gpsPort = PIOS_COM_GPS;
#ifdef MODULE_GPS_BUILTIN
gpsEnabled = true;
#else
HwSettingsInitialize();
uint8_t optionalModules[HWSETTINGS_OPTIONALMODULES_NUMELEM];
HwSettingsOptionalModulesGet(optionalModules);
if (optionalModules[HWSETTINGS_OPTIONALMODULES_GPS] == HWSETTINGS_OPTIONALMODULES_ENABLED)
gpsEnabled = true;
else
gpsEnabled = false;
#endif
#if defined(REVOLUTION)
// Revolution expects these objects to always be defined. Not doing so will fail some
// queue connections in navigation
GPSPositionInitialize();
GPSVelocityInitialize();
GPSTimeInitialize();
GPSSatellitesInitialize();
HomeLocationInitialize();
updateSettings();
#else
if (gpsPort && gpsEnabled) {
GPSPositionInitialize();
#if !defined(PIOS_GPS_MINIMAL)
GPSTimeInitialize();
GPSSatellitesInitialize();
#endif
#ifdef PIOS_GPS_SETS_HOMELOCATION
HomeLocationInitialize();
#endif
updateSettings();
}
#endif
if (gpsPort && gpsEnabled) {
gps_rx_buffer = pvPortMalloc(NMEA_MAX_PACKET_LENGTH);
PIOS_Assert(gps_rx_buffer);
return 0;
}
return -1;
}
MODULE_INITCALL(GPSInitialize, GPSStart)
// ****************
/**
* Main gps task. It does not return.
*/
static void gpsTask(void *parameters)
{
portTickType xDelay = 100 / portTICK_RATE_MS;
uint32_t timeNowMs = xTaskGetTickCount() * portTICK_RATE_MS;;
GPSPositionData GpsData;
UBXPacket *ubx = (UBXPacket *)gps_rx_buffer;
uint8_t rx_count = 0;
// bool start_flag = false;
bool found_cr = false;
enum proto_states {START,NMEA,UBX_SY2,UBX_CLASS,UBX_ID,UBX_LEN1,
UBX_LEN2,UBX_PAYLOAD,UBX_CHK1,UBX_CHK2};
enum proto_states proto_state = START;
int32_t gpsRxOverflow = 0;
numUpdates = 0;
numChecksumErrors = 0;
numParsingErrors = 0;
timeOfLastUpdateMs = timeNowMs;
timeOfLastCommandMs = timeNowMs;
GPSPositionGet(&GpsData);
// Loop forever
while (1)
{
uint8_t c;
// NMEA or SINGLE-SENTENCE GPS mode
// This blocks the task until there is something on the buffer
while (PIOS_COM_ReceiveBuffer(gpsPort, &c, 1, xDelay) > 0)
{
// detect start while acquiring stream
switch (proto_state)
{
case START: // detect protocol
switch (c)
{
case UBX_SYNC1: // first UBX sync char found
proto_state = UBX_SY2;
continue;
case '$': // NMEA identifier found
proto_state = NMEA;
found_cr = false;
rx_count = 0;
break;
default:
continue;
}
break;
case UBX_SY2:
if (c == UBX_SYNC2) // second UBX sync char found
{
proto_state = UBX_CLASS;
found_cr = false;
rx_count = 0;
}
else
{
proto_state = START; // reset state
}
continue;
case UBX_CLASS:
ubx->header.class = c;
proto_state = UBX_ID;
continue;
case UBX_ID:
ubx->header.id = c;
proto_state = UBX_LEN1;
continue;
case UBX_LEN1:
ubx->header.len = c;
proto_state = UBX_LEN2;
continue;
case UBX_LEN2:
ubx->header.len += (c << 8);
if ((sizeof (UBXHeader)) + ubx->header.len > NMEA_MAX_PACKET_LENGTH)
{
gpsRxOverflow++;
proto_state = START;
found_cr = false;
rx_count = 0;
}
else
{
proto_state = UBX_PAYLOAD;
}
continue;
case UBX_PAYLOAD:
if (rx_count < ubx->header.len)
{
ubx->payload.payload[rx_count] = c;
if (++rx_count == ubx->header.len)
proto_state = UBX_CHK1;
}
else
proto_state = START;
continue;
case UBX_CHK1:
ubx->header.ck_a = c;
proto_state = UBX_CHK2;
continue;
case UBX_CHK2:
ubx->header.ck_b = c;
if (checksum_ubx_message(ubx))
{
parse_ubx_message(ubx);
}
proto_state = START;
continue;
case NMEA:
break;
}
if (rx_count >= NMEA_MAX_PACKET_LENGTH)
{
// The buffer is already full and we haven't found a valid NMEA sentence.
// Flush the buffer and note the overflow event.
gpsRxOverflow++;
proto_state = START;
found_cr = false;
rx_count = 0;
}
else
{
gps_rx_buffer[rx_count] = c;
rx_count++;
}
// look for ending '\r\n' sequence
if (!found_cr && (c == '\r') )
found_cr = true;
else
if (found_cr && (c != '\n') )
found_cr = false; // false end flag
else
if (found_cr && (c == '\n') )
{
// The NMEA functions require a zero-terminated string
// As we detected \r\n, the string as for sure 2 bytes long, we will also strip the \r\n
gps_rx_buffer[rx_count-2] = 0;
// prepare to parse next sentence
proto_state = START;
found_cr = false;
rx_count = 0;
// Our rxBuffer must look like this now:
// [0] = '$'
// ... = zero or more bytes of sentence payload
// [end_pos - 1] = '\r'
// [end_pos] = '\n'
//
// Prepare to consume the sentence from the buffer
// Validate the checksum over the sentence
if (!NMEA_checksum(&gps_rx_buffer[1]))
{ // Invalid checksum. May indicate dropped characters on Rx.
//PIOS_DEBUG_PinHigh(2);
++numChecksumErrors;
//PIOS_DEBUG_PinLow(2);
}
else
{ // Valid checksum, use this packet to update the GPS position
if (!NMEA_update_position(&gps_rx_buffer[1],&GpsData)) {
//PIOS_DEBUG_PinHigh(2);
++numParsingErrors;
//PIOS_DEBUG_PinLow(2);
}
else
++numUpdates;
timeNowMs = xTaskGetTickCount() * portTICK_RATE_MS;
timeOfLastUpdateMs = timeNowMs;
timeOfLastCommandMs = timeNowMs;
}
}
}
// Check for GPS timeout
timeNowMs = xTaskGetTickCount() * portTICK_RATE_MS;
if ((timeNowMs - timeOfLastUpdateMs) >= GPS_TIMEOUT_MS)
{ // we have not received any valid GPS sentences for a while.
// either the GPS is not plugged in or a hardware problem or the GPS has locked up.
GpsData.Status = GPSPOSITION_STATUS_NOGPS;
GPSPositionSet(&GpsData);
AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_ERROR);
}
else
{ // we appear to be receiving GPS sentences OK, we've had an update
#ifdef PIOS_GPS_SETS_HOMELOCATION
HomeLocationData home;
HomeLocationGet(&home);
if ((GpsData.Status == GPSPOSITION_STATUS_FIX3D) && (home.Set == HOMELOCATION_SET_FALSE))
setHomeLocation(&GpsData);
#endif
//criteria for GPS-OK taken from this post...
//http://forums.openpilot.org/topic/1523-professors-insgps-in-svn/page__view__findpost__p__5220
if ((GpsData.PDOP < 3.5) && (GpsData.Satellites >= 7))
AlarmsClear(SYSTEMALARMS_ALARM_GPS);
else
if (GpsData.Status == GPSPOSITION_STATUS_FIX3D)
AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_WARNING);
else
AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_CRITICAL);
}
}
}
#ifdef PIOS_GPS_SETS_HOMELOCATION
/*
* Estimate the acceleration due to gravity for a particular location in LLA
*/
static float GravityAccel(float latitude, float longitude, float altitude)
{
// WGS84 gravity model. The effect of gravity over latitude is strong
// enough to change the estimated accelerometer bias in those apps.
double sinsq = sin((double)latitude);
sinsq *= sinsq;
// Likewise, over the altitude range of a high-altitude balloon, the effect
// due to change in altitude can also affect the model.
return (float)(9.7803267714 * (1 + 0.00193185138639*sinsq) / sqrt(1 - 0.00669437999013*sinsq)
- 3.086e-6*altitude);
}
// ****************
static void setHomeLocation(GPSPositionData * gpsData)
{
HomeLocationData home;
HomeLocationGet(&home);
GPSTimeData gps;
GPSTimeGet(&gps);
if (gps.Year >= 2000)
{
// Store LLA
home.Latitude = gpsData->Latitude;
home.Longitude = gpsData->Longitude;
home.Altitude = gpsData->Altitude + gpsData->GeoidSeparation;
// Compute home ECEF coordinates and the rotation matrix into NED
double LLA[3] = { ((double)home.Latitude) / 10e6, ((double)home.Longitude) / 10e6, ((double)home.Altitude) };
// Compute magnetic flux direction at home location
if (WMM_GetMagVector(LLA[0], LLA[1], LLA[2], gps.Month, gps.Day, gps.Year, &home.Be[0]) >= 0)
{ // calculations appeared to go OK
// Compute local acceleration due to gravity. Vehicles that span a very large
// range of altitude (say, weather balloons) may need to update this during the
// flight.
home.g_e = GravityAccel(LLA[0], LLA[1], LLA[2]);
home.Set = HOMELOCATION_SET_TRUE;
HomeLocationSet(&home);
}
}
}
#endif
/**
* Update the GPS settings, called on startup.
* FIXME: This should be in the GPSSettings object. But objects have
* too much overhead yet. Also the GPS has no any specific settings
* like protocol, etc. Thus the HwSettings object which contains the
* GPS port speed is used for now.
*/
static void updateSettings()
{
if (gpsPort) {
// Retrieve settings
uint8_t speed;
HwSettingsGPSSpeedGet(&speed);
// Set port speed
switch (speed) {
case HWSETTINGS_GPSSPEED_2400:
PIOS_COM_ChangeBaud(gpsPort, 2400);
break;
case HWSETTINGS_GPSSPEED_4800:
PIOS_COM_ChangeBaud(gpsPort, 4800);
break;
case HWSETTINGS_GPSSPEED_9600:
PIOS_COM_ChangeBaud(gpsPort, 9600);
break;
case HWSETTINGS_GPSSPEED_19200:
PIOS_COM_ChangeBaud(gpsPort, 19200);
break;
case HWSETTINGS_GPSSPEED_38400:
PIOS_COM_ChangeBaud(gpsPort, 38400);
break;
case HWSETTINGS_GPSSPEED_57600:
PIOS_COM_ChangeBaud(gpsPort, 57600);
break;
case HWSETTINGS_GPSSPEED_115200:
PIOS_COM_ChangeBaud(gpsPort, 115200);
break;
}
}
}
/**
* @}
* @}
*/
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