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PX4-Autopilot/src/drivers/gps/ashtech.cpp
Denis Yeldandi 6bf005e901 PASHS,POP,20 is needed for 20Hz configuration
2014-10-06 17:56:56 +04:00

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#include "ashtech.h"
#include <unistd.h>
#include <stdio.h>
#include <poll.h>
#include <math.h>
#include <string.h>
#include <assert.h>
#include <systemlib/err.h>
#include <uORB/uORB.h>
#include <uORB/topics/vehicle_gps_position.h>
#include <uORB/topics/satellite_info.h>
#include <drivers/drv_hrt.h>
#include <fcntl.h>
#include <math.h>
typedef double float64_t;
typedef float float32_t;
char* str_scanDec(const char *pos, int8_t sign, int8_t n_max_digit, int32_t *result)
{
int8_t n=0;
int32_t d=0;
int8_t neg = 0;
if(*pos == '-') { neg = 1; pos++; }
else if(*pos == '+') { pos++; }
else if(sign) return(NULL);
while(*pos >= '0' && *pos <= '9')
{
d = d*10 + (*(pos++) - '0');
n++;
if(n_max_digit>0 && n==n_max_digit) break;
}
if(n==0 || n>10) return(NULL);
if(neg) *result = -d;
else *result = d;
return((char *)pos);
}
char* scanFloat64(const char *pos, int8_t sign, int8_t n_max_int, int8_t n_max_frac,
float64_t *result)
{
float64_t f=0.0, div=1.0;
int32_t d_int;
int8_t n=0, isneg= 0;
if( *pos == '-' ) isneg= 1;
if((pos = str_scanDec(pos, sign, n_max_int, &d_int)) == NULL) return(NULL);
if(*(pos) == '.')
{
pos++;
while(*pos >= '0' && *pos <= '9')
{
f = f*(10.0) + (float64_t)(*(pos++) - '0');
div *= (0.1);
n++;
if(n_max_frac>0 && n==n_max_frac) break;
}
}
else if(n_max_frac > 0) return(NULL);
if( isneg ) *result = (float64_t)d_int - f*div;
else *result = (float64_t)d_int + f*div;
return((char *)pos);
}
ASHTECH::ASHTECH(const int &fd, struct vehicle_gps_position_s *gps_position, struct satellite_info_s *satellite_info):
_fd(fd),
_satellite_info(satellite_info),
_gps_position(gps_position)
{
decode_init();
_decode_state = NME_DECODE_UNINIT;
_rx_buffer_bytes = 0;
}
ASHTECH::~ASHTECH(){
}
//All NMEA descriptions are taken from
//http://www.trimble.com/OEM_ReceiverHelp/V4.44/en/NMEA-0183messages_MessageOverview.html
int ASHTECH::handle_message(int len){
if(len < 7) return 0;
int uiCalcComma = 0;
for(int i = 0 ; i < len; i++){
if(_rx_buffer[i] == ',')uiCalcComma++;
}
char* bufptr = (char*)( _rx_buffer+6);
if((memcmp(_rx_buffer+3, "ZDA,",3) == 0)&&(uiCalcComma == 6)){
/*
UTC day, month, and year, and local time zone offset
An example of the ZDA message string is:
$GPZDA,172809.456,12,07,1996,00,00*45
ZDA message fields
Field Meaning
0 Message ID $GPZDA
1 UTC
2 Day, ranging between 01 and 31
3 Month, ranging between 01 and 12
4 Year
5 Local time zone offset from GMT, ranging from 00 through <20>13 hours
6 Local time zone offset from GMT, ranging from 00 through 59 minutes
7 The checksum data, always begins with *
Fields 5 and 6 together yield the total offset. For example, if field 5 is -5 and field 6 is +15, local time is 5 hours and 15 minutes earlier than GMT.
*/
float64_t ashtech_time = 0.0;
int day = 0, month = 0,year = 0,local_time_off_hour = 0,local_time_off_min = 0;
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&ashtech_time);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &day);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &month);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &year);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &local_time_off_hour);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &local_time_off_min);
int ashtech_hour = ashtech_time/10000;
int ashtech_minute = (ashtech_time - ashtech_hour*10000)/100;
float64_t ashtech_sec = ashtech_time - ashtech_hour*10000 - ashtech_minute*100;
//convert to unix timestamp
struct tm timeinfo;
timeinfo.tm_year = year - 1900;
timeinfo.tm_mon = month - 1;
timeinfo.tm_mday = day;
timeinfo.tm_hour = ashtech_hour;
timeinfo.tm_min = ashtech_minute;
timeinfo.tm_sec = int(ashtech_sec);
time_t epoch = mktime(&timeinfo);
_gps_position->time_gps_usec = (uint64_t)epoch * 1000000; //TODO: test this
_gps_position->time_gps_usec += (uint64_t)((ashtech_sec - int(ashtech_sec)) * 1e6);
_gps_position->timestamp_time = hrt_absolute_time();
}
else if((memcmp(_rx_buffer+3, "GGA,",3) == 0)&&(uiCalcComma == 14)){
/*
Time, position, and fix related data
An example of the GBS message string is:
$GPGGA,172814.0,3723.46587704,N,12202.26957864,W,2,6,1.2,18.893,M,-25.669,M,2.0,0031*4F
Note - The data string exceeds the ASHTECH standard length.
GGA message fields
Field Meaning
0 Message ID $GPGGA
1 UTC of position fix
2 Latitude
3 Direction of latitude:
N: North
S: South
4 Longitude
5 Direction of longitude:
E: East
W: West
6 GPS Quality indicator:
0: Fix not valid
1: GPS fix
2: Differential GPS fix, OmniSTAR VBS
4: Real-Time Kinematic, fixed integers
5: Real-Time Kinematic, float integers, OmniSTAR XP/HP or Location RTK
7 Number of SVs in use, range from 00 through to 24+
8 HDOP
9 Orthometric height (MSL reference)
10 M: unit of measure for orthometric height is meters
11 Geoid separation
12 M: geoid separation measured in meters
13 Age of differential GPS data record, Type 1 or Type 9. Null field when DGPS is not used.
14 Reference station ID, range 0000-4095. A null field when any reference station ID is selected and no corrections are received1.
15
The checksum data, always begins with *
Note - If a user-defined geoid model, or an inclined
*/
float64_t ashtech_time = 0.0, lat = 0.0, lon = 0.0, alt = 0.0;
int num_of_sv = 0, fix_quality=0;
float64_t hdop = 99.9;
char ns = '?', ew = '?';
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&ashtech_time);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&lat);
if(bufptr && *(++bufptr) != ',') ns = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&lon);
if(bufptr && *(++bufptr) != ',') ew = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &fix_quality);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &num_of_sv);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&hdop);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&alt);
if(ns == 'S')
lat = -lat;
if(ew == 'W')
lon = -lon;
_gps_position->lat = (int(lat*0.01) + (lat*0.01 - int(lat*0.01))*100.0/60.0)*10000000;
_gps_position->lon = (int(lon*0.01) + (lon*0.01 - int(lon*0.01))*100.0/60.0)*10000000;
_gps_position->alt = alt*1000;
_rate_count_lat_lon++;
if((lat == 0.0) && (lon == 0.0) && (alt == 0.0)){
_gps_position->fix_type = 0;
}
else
_gps_position->fix_type = 3 + fix_quality;
_gps_position->timestamp_position = hrt_absolute_time();
_gps_position->vel_m_s = 0; /**< GPS ground speed (m/s) */
_gps_position->vel_n_m_s = 0; /**< GPS ground speed in m/s */
_gps_position->vel_e_m_s = 0; /**< GPS ground speed in m/s */
_gps_position->vel_d_m_s = 0; /**< GPS ground speed in m/s */
_gps_position->cog_rad = 0; /**< Course over ground (NOT heading, but direction of movement) in rad, -PI..PI */
_gps_position->vel_ned_valid = true; /**< Flag to indicate if NED speed is valid */
_gps_position->c_variance_rad = 0.1;
_gps_position->timestamp_velocity = hrt_absolute_time();
return 1;
}
else if ((memcmp(_rx_buffer, "$PASHR,POS,", 11) == 0) && (uiCalcComma == 18)) {
/*
Example $PASHR,POS,2,10,125410.00,5525.8138702,N,03833.9587380,E,131.555,1.0,0.0,0.007,-0.001,2.0,1.0,1.7,1.0,*34
$PASHR,POS,d1,d2,m3,m4,c5,m6,c7,f8,f9,f10,f11,f12,f13,f14,f15,f16,s17*cc
Parameter Description Range
d1 Position mode 0: standalone
1: differential
2: RTK float
3: RTK fixed
5: Dead reckoning
9: SBAS (see NPT setting)
d2 Number of satellite used in position fix 0-99
m3 Current UTC time of position fix (hhmmss.ss) 000000.00-235959.99
m4 Latitude of position (ddmm.mmmmmm) 0-90 degrees 00-59.9999999 minutes
c5 Latitude sector N, S
m6 Longitude of position (dddmm.mmmmmm) 0-180 degrees 00-59.9999999 minutes
c7 Longitude sector E,W
f8 Altitude above ellipsoid +9999.000
f9 Differential age (data link age), seconds 0.0-600.0
f10 True track/course over ground in degrees 0.0-359.9
f11 Speed over ground in knots 0.0-999.9
f12 Vertical velocity in decimeters per second +999.9
f13 PDOP 0-99.9
f14 HDOP 0-99.9
f15 VDOP 0-99.9
f16 TDOP 0-99.9
s17 Reserved no data
*cc Checksum
*/
bufptr = (char*)( _rx_buffer+10);
float64_t ashtech_time = 0.0, lat = 0.0, lon = 0.0, alt = 0.0;
int num_of_sv = 0, fix_quality=0;
float64_t track_true = 0.0, ground_speed = 0.0 , age_of_corr = 0.0;
float64_t hdop = 99.9, vdop = 99.9, pdop = 99.9, tdop = 99.9,vertic_vel = 0.0;
char ns = '?', ew = '?';
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &fix_quality);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &num_of_sv);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&ashtech_time);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&lat);
if(bufptr && *(++bufptr) != ',') ns = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&lon);
if(bufptr && *(++bufptr) != ',') ew = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&alt);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&age_of_corr);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&track_true);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&ground_speed);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&vertic_vel);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&pdop);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&hdop);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&vdop);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&tdop);
if(ns == 'S')
lat = -lat;
if(ew == 'W')
lon = -lon;
_gps_position->lat = (int(lat*0.01) + (lat*0.01 - int(lat*0.01))*100.0/60.0)*10000000;
_gps_position->lon = (int(lon*0.01) + (lon*0.01 - int(lon*0.01))*100.0/60.0)*10000000;
_gps_position->alt = alt*1000;
_rate_count_lat_lon++;
if((lat == 0.0) && (lon == 0.0) && (alt == 0.0)){
_gps_position->fix_type = 0;
}
else
_gps_position->fix_type = 3 + fix_quality;
_gps_position->timestamp_position = hrt_absolute_time();
const float64_t m_pi = 3.14159265;
double track_rad = track_true * m_pi / 180.0;
double velocity_ms = ground_speed / 1.9438445; /** knots to m/s */
double velocity_north = velocity_ms * cos(track_rad);
double velocity_east = velocity_ms * sin(track_rad);
_gps_position->vel_m_s = velocity_ms; /**< GPS ground speed (m/s) */
_gps_position->vel_n_m_s = velocity_north; /**< GPS ground speed in m/s */
_gps_position->vel_e_m_s = velocity_east; /**< GPS ground speed in m/s */
_gps_position->vel_d_m_s = -vertic_vel; /**< GPS ground speed in m/s */
_gps_position->cog_rad = track_rad; /**< Course over ground (NOT heading, but direction of movement) in rad, -PI..PI */
_gps_position->vel_ned_valid = true; /**< Flag to indicate if NED speed is valid */
_gps_position->c_variance_rad = 0.1;
_gps_position->timestamp_velocity = hrt_absolute_time();
return 1;
}
else if((memcmp(_rx_buffer+3, "GST,",3) == 0)&&(uiCalcComma == 8)){
/*
Position error statistics
An example of the GST message string is:
$GPGST,172814.0,0.006,0.023,0.020,273.6,0.023,0.020,0.031*6A
The Talker ID ($--) will vary depending on the satellite system used for the position solution:
$GP - GPS only
$GL - GLONASS only
$GN - Combined
GST message fields
Field Meaning
0 Message ID $GPGST
1 UTC of position fix
2 RMS value of the pseudorange residuals; includes carrier phase residuals during periods of RTK (float) and RTK (fixed) processing
3 Error ellipse semi-major axis 1 sigma error, in meters
4 Error ellipse semi-minor axis 1 sigma error, in meters
5 Error ellipse orientation, degrees from true north
6 Latitude 1 sigma error, in meters
7 Longitude 1 sigma error, in meters
8 Height 1 sigma error, in meters
9 The checksum data, always begins with *
*/
float64_t ashtech_time = 0.0, lat_err = 0.0, lon_err = 0.0, alt_err = 0.0;
float64_t min_err = 0.0, maj_err = 0.0, deg_from_north = 0.0, rms_err = 0.0;
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&ashtech_time);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&rms_err);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&maj_err);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&min_err);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&deg_from_north);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&lat_err);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&lon_err);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&alt_err);
_gps_position->eph = sqrt(lat_err*lat_err +lon_err*lon_err);
_gps_position->epv = alt_err;
_gps_position->s_variance_m_s = 0;
_gps_position->timestamp_variance = hrt_absolute_time();
}
else if((memcmp(_rx_buffer+3, "VTG,",3) == 0)&&(uiCalcComma == 9)){
/*
Track made good and speed over ground
An example of the VTG message string is:
$GPVTG,054.7,T,034.4,M,005.5,N,010.2,K*48
VTG message fields
Field Meaning
0 Message ID $GPVTG
1 Track made good (degrees true)
2 T: track made good is relative to true north
3 Track made good (degrees magnetic)
4 M: track made good is relative to magnetic north
5 Speed, in knots
6 N: speed is measured in knots
7 Speed over ground in kilometers/hour (kph)
8 K: speed over ground is measured in kph
9 The checksum data, always begins with *
*/
/*float64_t track_true = 0.0, speed = 0.0, track_magnetic = 0.0, ground_speed = 0.0;
char true_north = '?', magnetic_north = '?', speed_in_knots = '?', speed_in_kph = '?';
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&track_true);
if(bufptr && *(++bufptr) != ',') true_north = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&track_magnetic);
if(bufptr && *(++bufptr) != ',') magnetic_north = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&speed);
if(bufptr && *(++bufptr) != ',') speed_in_knots = *(bufptr++);
if(bufptr && *(++bufptr) != ',') bufptr = scanFloat64(bufptr, 0, 9, 9,&ground_speed);
if(bufptr && *(++bufptr) != ',') speed_in_kph = *(bufptr++);
const float64_t dPI = 3.14159265;
float64_t tan_C = tan(track_true * dPI / 180.0);
float64_t lat_ = sqrt(ground_speed*ground_speed/ (1+tan_C)); //km/hour
float64_t lon_ = lat_*tan_C; // //km/hour*/
}
else if((memcmp(_rx_buffer+3, "GSV,",3) == 0)){
/*
The GSV message string identifies the number of SVs in view, the PRN numbers, elevations, azimuths, and SNR values. An example of the GSV message string is:
$GPGSV,4,1,13,02,02,213,,03,-3,000,,11,00,121,,14,13,172,05*67
GSV message fields
Field Meaning
0 Message ID $GPGSV
1 Total number of messages of this type in this cycle
2 Message number
3 Total number of SVs visible
4 SV PRN number
5 Elevation, in degrees, 90<39> maximum
6 Azimuth, degrees from True North, 000<30> through 359<35>
7 SNR, 00 through 99 dB (null when not tracking)
8-11 Information about second SV, same format as fields 4 through 7
12-15 Information about third SV, same format as fields 4 through 7
16-19 Information about fourth SV, same format as fields 4 through 7
20 The checksum data, always begins with *
*/
// currently process only gps, because do not know what
// Global satellite ID I should use for non GPS sats
bool bGPS = false;
if(memcmp(_rx_buffer, "$GP",3) != 0)
return 0;
else
bGPS = true;
int all_msg_num, this_msg_num, tot_sv_visible;
struct gsv_sat{
int svid;
int elevation;
int azimuth;
int snr;
} sat[4];
memset(sat, 0, sizeof(sat));
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &all_msg_num);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &this_msg_num);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &tot_sv_visible);
if((this_msg_num<1) || (this_msg_num>all_msg_num)){
return 0;
}
if((this_msg_num == 0)&&(bGPS == true)){
memset(_satellite_info->svid, 0,sizeof(_satellite_info->svid));
memset(_satellite_info->used, 0,sizeof(_satellite_info->used));
memset(_satellite_info->snr, 0,sizeof(_satellite_info->snr));
memset(_satellite_info->elevation,0,sizeof(_satellite_info->elevation));
memset(_satellite_info->azimuth, 0,sizeof(_satellite_info->azimuth));
}
int end = 4;
if(this_msg_num == all_msg_num){
end = tot_sv_visible - (this_msg_num-1)*4;
_gps_position->satellites_used = tot_sv_visible;
_satellite_info->count = SAT_INFO_MAX_SATELLITES;
_satellite_info->timestamp = hrt_absolute_time();
}
for(int y = 0 ; y < end ;y++){
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &sat[y].svid);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &sat[y].elevation);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &sat[y].azimuth);
if(bufptr && *(++bufptr) != ',') bufptr = str_scanDec(bufptr, 0, 9, &sat[y].snr);
_satellite_info->svid[y+(this_msg_num-1)*4] = sat[y].svid;
_satellite_info->used[y+(this_msg_num-1)*4] = ((sat[y].snr>0)? true: false);
_satellite_info->snr[y+(this_msg_num-1)*4] = sat[y].snr;
_satellite_info->elevation[y+(this_msg_num-1)*4] = sat[y].elevation;
_satellite_info->azimuth[y+(this_msg_num-1)*4] = sat[y].azimuth;
}
}
return 0;
}
int ASHTECH::receive(unsigned timeout){
{
/* poll descriptor */
pollfd fds[1];
fds[0].fd = _fd;
fds[0].events = POLLIN;
uint8_t buf[32];
/* timeout additional to poll */
uint64_t time_started = hrt_absolute_time();
int j = 0;
ssize_t count = 0;
while (true) {
/* pass received bytes to the packet decoder */
while (j < count) {
int l=0;
if ((l = parse_char(buf[j])) > 0) {
/* return to configure during configuration or to the gps driver during normal work
* if a packet has arrived */
if (handle_message(l) > 0)
return 1;
}
/* in case we keep trying but only get crap from GPS */
if (time_started + timeout*1000*2 < hrt_absolute_time() ) {
return -1;
}
j++;
}
/* everything is read */
j = count = 0;
/* then poll for new data */
int ret = ::poll(fds, sizeof(fds) / sizeof(fds[0]), timeout*2);
if (ret < 0) {
/* something went wrong when polling */
return -1;
} else if (ret == 0) {
/* Timeout */
return -1;
} else if (ret > 0) {
/* if we have new data from GPS, go handle it */
if (fds[0].revents & POLLIN) {
/*
* We are here because poll says there is some data, so this
* won't block even on a blocking device. If more bytes are
* available, we'll go back to poll() again...
*/
count = ::read(_fd, buf, sizeof(buf));
}
}
}
}
}
#define HEXDIGIT_CHAR(d) ((char)((d) + (((d) < 0xA) ? '0' : 'A'-0xA)))
int ASHTECH::parse_char(uint8_t b)
{
int iRet = 0;
switch (_decode_state) {
/* First, look for sync1 */
case NME_DECODE_UNINIT:
if (b == '$') {
_decode_state = NME_DECODE_GOT_SYNC1;
_rx_buffer_bytes = 0;
_rx_buffer[_rx_buffer_bytes++] = b;
}
break;
case NME_DECODE_GOT_SYNC1:
if (b == '$') {
_decode_state = NME_DECODE_GOT_SYNC1;
_rx_buffer_bytes = 0;
} else if (b == '*') {
_decode_state = NME_DECODE_GOT_ASTERIKS;
}
if (_rx_buffer_bytes >= (sizeof(_rx_buffer) - 5)) {
_decode_state = NME_DECODE_UNINIT;
_rx_buffer_bytes = 0;
} else
_rx_buffer[_rx_buffer_bytes++] = b;
break;
case NME_DECODE_GOT_ASTERIKS:
_rx_buffer[_rx_buffer_bytes++] = b;
_decode_state = NME_DECODE_GOT_FIRST_CS_BYTE;
break;
case NME_DECODE_GOT_FIRST_CS_BYTE:
_rx_buffer[_rx_buffer_bytes++] = b;
uint8_t checksum = 0;
uint8_t *buffer = _rx_buffer + 1;
uint8_t *bufend = _rx_buffer + _rx_buffer_bytes - 3;
for (; buffer < bufend; buffer++) checksum ^= *buffer;
if ((HEXDIGIT_CHAR(checksum >> 4) == *(_rx_buffer + _rx_buffer_bytes - 2)) &&
(HEXDIGIT_CHAR(checksum & 0x0F) == *(_rx_buffer + _rx_buffer_bytes - 1))) {
iRet = _rx_buffer_bytes;
}
_decode_state = NME_DECODE_UNINIT;
_rx_buffer_bytes = 0;
break;
}
return iRet;
}
void ASHTECH::decode_init(void){
}
//ashtech boad configuration script
//char comm[] = "$PASHS,NME,GGA,A,ON,0.1\r\n"
char comm[] = "$PASHS,POP,20\r\n"\
"$PASHS,NME,ZDA,B,ON,3\r\n"\
"$PASHS,NME,GGA,B,OFF\r\n"\
"$PASHS,NME,GST,B,ON,3\r\n"\
"$PASHS,NME,POS,B,ON,0.05\r\n"\
"$PASHS,NME,GSV,B,ON,3\r\n"\
"$PASHS,SPD,A,8\r\n"\
"$PASHS,SPD,B,9\r\n"; // default baud is 7
int ASHTECH::configure(unsigned &baudrate){
/* try different baudrates */
const unsigned baudrates_to_try[] = {9600, 38400, 19200, 57600, 115200};
for (int baud_i = 0; baud_i < sizeof(baudrates_to_try)/sizeof(baudrates_to_try[0]); baud_i++) {
baudrate = baudrates_to_try[baud_i];
set_baudrate(_fd, baudrate);
write(_fd, (uint8_t*)comm, sizeof(comm));
}
set_baudrate(_fd, 115200);
return 0;
}
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