#!/usr/bin/env python # $Id: gps.py 5163 2009-02-12 22:08:31Z esr $ # # gps.py -- Python interface to GPSD. # import time, calendar, math, socket, sys, select api_major_version = 3 # bumped on incompatible changes api_minor_version = 1 # bumped on compatible changes NaN = float('nan') def isnan(x): return str(x) == 'nan' ONLINE_SET = 0x00000001 TIME_SET = 0x00000002 TIMERR_SET = 0x00000004 LATLON_SET = 0x00000008 ALTITUDE_SET = 0x00000010 SPEED_SET = 0x00000020 TRACK_SET = 0x00000040 CLIMB_SET = 0x00000080 STATUS_SET = 0x00000100 MODE_SET = 0x00000200 HDOP_SET = 0x00000400 VDOP_SET = 0x00000800 PDOP_SET = 0x00001000 TDOP_SET = 0x00002000 GDOP_SET = 0x00004000 HERR_SET = 0x00008000 VERR_SET = 0x00010000 PERR_SET = 0x00020000 SATELLITE_SET = 0x00040000 SPEEDERR_SET = 0x00080000 TRACKERR_SET = 0x00100000 CLIMBERR_SET = 0x00200000 DEVICE_SET = 0x00400000 DEVICELIST_SET = 0x00800000 DEVICEID_SET = 0x01000000 ERROR_SET = 0x02000000 CYCLE_START_SET = 0x04000000 FIX_SET = (TIME_SET|MODE_SET|TIMERR_SET|LATLON_SET|HERR_SET|ALTITUDE_SET|VERR_SET|TRACK_SET|TRACKERR_SET|SPEED_SET|SPEEDERR_SET|CLIMB_SET|CLIMBERR_SET) STATUS_NO_FIX = 0 STATUS_FIX = 1 STATUS_DGPS_FIX = 2 MODE_NO_FIX = 1 MODE_2D = 2 MODE_3D = 3 MAXCHANNELS = 12 SIGNAL_STRENGTH_UNKNOWN = NaN # The spec says 82, but some receivers (TN-200, GSW 2.3.2) output 86 characters NMEA_MAX = 86 GPSD_PORT = 2947 class gpstimings: def __init__(self): self.sentence_tag = "" self.sentence_length = 0 self.sentence_time = 0.0 self.d_xmit_time = 0.0 self.d_recv_time = 0.0 self.d_decode_time = 0.0 self.emit_time = 0.0 self.poll_time = 0.0 self.c_recv_time = 0.0 self.c_decode_time = 0.0 def d_received(self): if self.sentence_time: return self.d_recv_time + self.sentence_time else: return self.d_recv_time + self.d_xmit_time def collect(self, tag, length, sentence_time, xmit_time, recv_time, decode_time, poll_time, emit_time): self.sentence_tag = tag self.sentence_length = int(length) self.sentence_time = float(sentence_time) self.d_xmit_time = float(xmit_time) self.d_recv_time = float(recv_time) self.d_decode_time = float(decode_time) self.poll_time = float(poll_time) self.emit_time = float(emit_time) def __str__(self): return "%s\t%2d\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\t%2.6f\n" \ % (self.sentence_tag, self.sentence_length, self.sentence_time, self.d_xmit_time, self.d_recv_time, self.d_decode_time, self.poll_time, self.emit_time, self.c_recv_time, self.c_decode_time) class gpsfix: def __init__(self): self.mode = MODE_NO_FIX self.time = NaN self.ept = NaN self.latitude = self.longitude = 0.0 self.eph = NaN self.altitude = NaN # Meters self.epv = NaN self.track = NaN # Degrees from true north self.speed = NaN # Knots self.climb = NaN # Meters per second self.epd = NaN self.eps = NaN self.epc = NaN class gpsdata: "Position, track, velocity and status information returned by a GPS." class satellite: def __init__(self, PRN, elevation, azimuth, ss, used=None): self.PRN = PRN self.elevation = elevation self.azimuth = azimuth self.ss = ss self.used = used def __repr__(self): return "PRN: %3d E: %3d Az: %3d Ss: %d Used: %s" % (self.PRN,self.elevation,self.azimuth,self.ss,"ny"[self.used]) def __init__(self): # Initialize all data members self.online = 0 # NZ if GPS on, zero if not self.valid = 0 self.fix = gpsfix() self.status = STATUS_NO_FIX self.utc = "" self.satellites_used = 0 # Satellites used in last fix self.pdop = self.hdop = self.vdop = self.tdop = self.gdop = 0.0 self.epe = 0.0 self.satellites = [] # satellite objects in view self.await = self.parts = 0 self.gps_id = None self.driver_mode = 0 self.profiling = False self.timings = gpstimings() self.baudrate = 0 self.stopbits = 0 self.cycle = 0 self.mincycle = 0 self.device = None self.devices = [] def __repr__(self): st = "Time: %s (%s)" % (self.utc, self.fix.time) st += "Lat/lon: %f %f\n" % (self.fix.latitude, self.fix.longitude) if isnan(self.fix.altitude): st += "Altitude: ?\n" else: st += "Altitude: %f\n" % (self.fix.altitude) if isnan(self.fix.speed): st += "Speed: ?\n" else: st += "Speed: %f\n" % (self.fix.speed) if isnan(self.fix.track): st += "Track: ?\n" else: st += "Track: %f\n" % (self.fix.track) st += "Status: STATUS_%s\n" %("NO_FIX","FIX","DGPS_FIX")[self.status] st += "Mode: MODE_"+("ZERO", "NO_FIX", "2D","3D")[self.fix.mode]+"\n" st += "Quality: %d p=%2.2f h=%2.2f v=%2.2f t=%2.2f g=%2.2f\n" % \ (self.satellites_used, self.pdop, self.hdop, self.vdop, self.tdop, self.gdop) st += "Y: %s satellites in view:\n" % len(self.satellites) for sat in self.satellites: st += " " + repr(sat) + "\n" return st class gps(gpsdata): "Client interface to a running gpsd instance." def __init__(self, host="127.0.0.1", port="2947", verbose=0): gpsdata.__init__(self) self.sock = None # in case we blow up in connect self.sockfile = None self.connect(host, port) self.verbose = verbose self.raw_hook = None def connect(self, host, port): """Connect to a host on a given port. If the hostname ends with a colon (`:') followed by a number, and there is no port specified, that suffix will be stripped off and the number interpreted as the port number to use. """ if not port and (host.find(':') == host.rfind(':')): i = host.rfind(':') if i >= 0: host, port = host[:i], host[i+1:] try: port = int(port) except ValueError: raise socket.error, "nonnumeric port" if not port: port = GPSD_PORT #if self.debuglevel > 0: print 'connect:', (host, port) msg = "getaddrinfo returns an empty list" self.sock = None self.sockfile = None for res in socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM): af, socktype, proto, canonname, sa = res try: self.sock = socket.socket(af, socktype, proto) #if self.debuglevel > 0: print 'connect:', (host, port) self.sock.connect(sa) self.sockfile = self.sock.makefile() except socket.error, msg: #if self.debuglevel > 0: print 'connect fail:', (host, port) self.close() continue break if not self.sock: raise socket.error, msg def set_raw_hook(self, hook): self.raw_hook = hook def close(self): if self.sockfile: self.sockfile.close() if self.sock: self.sock.close() self.sock = None self.sockfile = None def __del__(self): self.close() def __unpack(self, buf): # unpack a daemon response into the instance members self.fix.time = 0.0 fields = buf.strip().split(",") if fields[0] == "GPSD": for field in fields[1:]: if not field or field[1] != '=': continue cmd = field[0] data = field[2:] if data[0] == "?": continue if cmd in ('A', 'a'): self.fix.altitude = float(data) self.valid |= ALTITUDE_SET elif cmd in ('B', 'b'): if data == '?': self.baudrate = self.stopbits = 0 self.device = None else: (f1, f2, f3, f4) = data.split() self.baudrate = int(f1) self.stopbits = int(f4) elif cmd in ('C', 'c'): if data == '?': self.cycle = -1 self.device = None elif len(data.split()) == 2: (self.cycle, self.mincycle) = map(float, data) else: self.mincycle = self.cycle = float(data) elif cmd in ('D', 'd'): self.utc = data self.fix.time = isotime(self.utc) self.valid |= TIME_SET elif cmd in ('E', 'e'): parts = data.split() (self.epe, self.fix.eph, self.fix.epv) = map(float, parts) self.valid |= HERR_SET | VERR_SET | PERR_SET elif cmd in ('F', 'f'): if data == '?': self.device = None else: self.device = data elif cmd in ('I', 'i'): if data == '?': self.cycle = -1 self.gps_id = None else: self.gps_id = data elif cmd in ('K', 'K'): if data == '?': self.devices = None else: self.devices = data[1:].split() elif cmd in ('M', 'm'): self.fix.mode = int(data) self.valid |= MODE_SET elif cmd in ('N', 'n'): if data == '?': self.driver_mode = -1 self.device = None else: self.driver_mode = int(data) elif cmd in ('O', 'o'): fields = data.split() if fields[0] == '?': self.fix.mode = MODE_NO_FIX else: self.timings.sentence_tag = fields[0] def default(i, cnv=float): if fields[i] == '?': return NaN else: return cnv(fields[i]) self.utc = fields[1] self.fix.time = default(1) if not isnan(self.fix.time): self.utc = isotime(self.fix.time) self.fix.ept = default(2) self.fix.latitude = default(3) self.fix.longitude = default(4) self.fix.altitude = default(5) self.fix.eph = default(6) self.fix.epv = default(7) self.fix.track = default(8) self.fix.speed = default(9) self.fix.climb = default(10) self.fix.epd = default(11) self.fix.eps = default(12) self.fix.epc = default(13) if len(fields) > 14: self.fix.mode = default(14, int) else: if isnan(self.fix.altitude): self.fix.mode = MODE_2D else: self.fix.mode = MODE_3D self.valid = TIME_SET|TIMERR_SET|LATLON_SET|MODE_SET if self.fix.mode == MODE_3D: self.valid |= ALTITUDE_SET | CLIMB_SET if not isnan(self.fix.eph): self.valid |= HERR_SET if not isnan(self.fix.epv): self.valid |= VERR_SET if not isnan(self.fix.track): self.valid |= TRACK_SET | SPEED_SET if not isnan(self.fix.eps): self.valid |= SPEEDERR_SET if not isnan(self.fix.epc): self.valid |= CLIMBERR_SET elif cmd in ('P', 'p'): (self.fix.latitude, self.fix.longitude) = map(float, data.split()) self.valid |= LATLON_SET elif cmd in ('Q', 'q'): parts = data.split() self.satellites_used = int(parts[0]) (self.pdop, self.hdop, self.vdop, self.tdop, self.gdop) = map(float, parts[1:]) self.valid |= HDOP_SET | VDOP_SET | PDOP_SET | TDOP_SET | GDOP_SET elif cmd in ('S', 's'): self.status = int(data) self.valid |= STATUS_SET elif cmd in ('T', 't'): self.fix.track = float(data) self.valid |= TRACK_SET elif cmd in ('U', 'u'): self.fix.climb = float(data) self.valid |= CLIMB_SET elif cmd in ('V', 'v'): self.fix.speed = float(data) self.valid |= SPEED_SET elif cmd in ('X', 'x'): if data == '?': self.online = -1 self.device = None else: self.online = float(data) self.valid |= ONLINE_SET elif cmd in ('Y', 'y'): satellites = data.split(":") prefix = satellites.pop(0).split() self.timings.sentence_tag = prefix.pop(0) self.timings.sentence_time = prefix.pop(0) if self.timings.sentence_time != "?": self.timings.sentence_time = float(self.timings.sentence_time) d1 = int(prefix.pop(0)) newsats = [] for i in range(d1): newsats.append(gps.satellite(*map(int, satellites[i].split()))) self.satellites = newsats self.valid |= SATELLITE_SET elif cmd in ('Z', 'z'): self.profiling = (data[0] == '1') elif cmd == '$': self.timings.collect(*data.split()) if self.raw_hook: self.raw_hook(buf); def waiting(self): "Return True if data is ready for the client." (winput,woutput,wexceptions) = select.select((self.sock,), (),(), 0) return winput != [] def poll(self): "Wait for and read data being streamed from gpsd." self.response = self.sockfile.readline() if self.response.startswith("H") and "=" not in self.response: while True: frag = self.sockfile.readline() self.response += frag if frag.startswith("."): break if not self.response: return -1 if self.verbose: sys.stderr.write("GPS DATA %s\n" % repr(self.response)) self.timings.c_recv_time = time.time() self.__unpack(self.response) if self.profiling: if self.timings.sentence_time != '?': basetime = self.timings.sentence_time else: basetime = self.timings.d_xmit_time self.timings.c_decode_time = time.time() - basetime self.timings.c_recv_time -= basetime return 0 def send(self, commands): "Ship commands to the daemon." if not commands.endswith("\n"): commands += "\n" self.sock.send(commands) def query(self, commands): "Send a command, get back a response." self.send(commands) return self.poll() # some multipliers for interpreting GPS output METERS_TO_FEET = 3.2808399 METERS_TO_MILES = 0.00062137119 KNOTS_TO_MPH = 1.1507794 # EarthDistance code swiped from Kismet and corrected # (As yet, this stuff is not in the libgps C library.) def Deg2Rad(x): "Degrees to radians." return x * (math.pi/180) def Rad2Deg(x): "Radians to degress." return x * (180/math.pi) def CalcRad(lat): "Radius of curvature in meters at specified latitude." a = 6378.137 e2 = 0.081082 * 0.081082 # the radius of curvature of an ellipsoidal Earth in the plane of a # meridian of latitude is given by # # R' = a * (1 - e^2) / (1 - e^2 * (sin(lat))^2)^(3/2) # # where a is the equatorial radius, # b is the polar radius, and # e is the eccentricity of the ellipsoid = sqrt(1 - b^2/a^2) # # a = 6378 km (3963 mi) Equatorial radius (surface to center distance) # b = 6356.752 km (3950 mi) Polar radius (surface to center distance) # e = 0.081082 Eccentricity sc = math.sin(Deg2Rad(lat)) x = a * (1.0 - e2) z = 1.0 - e2 * sc * sc y = pow(z, 1.5) r = x / y r = r * 1000.0 # Convert to meters return r def EarthDistance((lat1, lon1), (lat2, lon2)): "Distance in meters between two points specified in degrees." x1 = CalcRad(lat1) * math.cos(Deg2Rad(lon1)) * math.sin(Deg2Rad(90-lat1)) x2 = CalcRad(lat2) * math.cos(Deg2Rad(lon2)) * math.sin(Deg2Rad(90-lat2)) y1 = CalcRad(lat1) * math.sin(Deg2Rad(lon1)) * math.sin(Deg2Rad(90-lat1)) y2 = CalcRad(lat2) * math.sin(Deg2Rad(lon2)) * math.sin(Deg2Rad(90-lat2)) z1 = CalcRad(lat1) * math.cos(Deg2Rad(90-lat1)) z2 = CalcRad(lat2) * math.cos(Deg2Rad(90-lat2)) a = (x1*x2 + y1*y2 + z1*z2)/pow(CalcRad((lat1+lat2)/2), 2) # a should be in [1, -1] but can sometimes fall outside it by # a very small amount due to rounding errors in the preceding # calculations (this is prone to happen when the argument points # are very close together). Thus we constrain it here. if abs(a) > 1: a = 1 elif a < -1: a = -1 return CalcRad((lat1+lat2) / 2) * math.acos(a) def MeterOffset((lat1, lon1), (lat2, lon2)): "Return offset in meters of second arg from first." dx = EarthDistance((lat1, lon1), (lat1, lon2)) dy = EarthDistance((lat1, lon1), (lat2, lon1)) if lat1 < lat2: dy *= -1 if lon1 < lon2: dx *= -1 return (dx, dy) def isotime(s): "Convert timestamps in ISO8661 format to and from Unix time." if type(s) == type(1): return time.strftime("%Y-%m-%dT%H:%M:%S", time.gmtime(s)) elif type(s) == type(1.0): date = int(s) msec = s - date date = time.strftime("%Y-%m-%dT%H:%M:%S", time.gmtime(s)) return date + "." + `msec`[2:] elif type(s) == type(""): if s[-1] == "Z": s = s[:-1] if "." in s: (date, msec) = s.split(".") else: date = s msec = "0" # Note: no leap-second correction! return calendar.timegm(time.strptime(date, "%Y-%m-%dT%H:%M:%S")) + float("0." + msec) else: raise TypeError if __name__ == '__main__': import readline print "This is the exerciser for the Python gps interface." session = gps() session.set_raw_hook(lambda s: sys.stdout.write(s + "\n")) try: while True: commands = raw_input("> ") session.query(commands+"\n") print session except EOFError: print "Goodbye!" del session # gps.py ends here