add mini GNSS Data analysis

Author: shaoziyang

gnss/ugnss.py

@@ -0,0 +1,179 @@
+'''
+    mini GNSS Data analysis
+
+'''
+
+class uGNSS():
+
+    GNSS_DIR = ('N', 'NNE', 'NE', 'ENE', 'E', 'ESE', 'SE', 'SSE', 'S',
+                'SSW', 'SW', 'WSW', 'W', 'WNW', 'NW', 'NNW')
+    GNSS_VALID = (b'1', b'2')
+
+    def __init__(self, bufsize = 2048):
+
+        self.latitude = 0.0
+        self.longitude = 0.0
+        self.latitude_dir = 'N'
+        self.longitude_dir = 'E'
+        self.speed = 0.0
+        self.course = 0.0
+        self.altitude = 0.0
+        self.geoid_height = 0.0
+        self.date = [0, 0, 0]
+        self.time = [0, 0, 0]
+        self.datetime = [0, 0, 0, 0, 0, 0, 0, 0]
+        self.valid = False
+        self.satellites_in_view = 0
+        self.satellites_in_use = 0
+        self.satellites_used = []
+        self.hdop = 0.0
+        self.pdop = 0.0
+        self.vdop = 0.0
+        self._crc = bytearray(1)
+        self._buf = bytearray(256)
+        self._pos = 0
+        self._seg = []
+
+    def DM2DMS(dm):
+        return
+
+    def checksum(self, buf, length):
+        self._crc[0] = 0
+        for i in range(1, length):
+            self._crc[0] ^= buf[i]
+        try:
+            d = int(b'0x'+buf[length+1:length+3])
+        except:
+            return False
+        return self._crc[0] == d
+
+    def parse(self):
+        try:
+            if not self.checksum(self._buf, self._pos-4):
+                return False
+
+            self._seg = bytes(self._buf[1:self._pos-4]).split(b',')
+            if self._seg[0] in self.GNSS_CMD:
+                try:
+                    self.GNSS_CMD[self._seg[0]](self)
+                    return True
+                except:
+                    return False
+
+            return False
+        finally:
+            self._pos = 0
+
+    def update_char(self, c):
+        if self._pos:
+            if self._pos > 250:
+                self._pos = 0
+                return False
+            else:
+                if type(c) is int:
+                    self._buf[self._pos] = c
+                elif type(c) is str:
+                    self._buf[self._pos] = ord(c)
+                else:
+                    self._pos = 0
+                    return False
+
+                if self._buf[self._pos] == ord('\n'):
+                    return self.parse()
+                else:
+                    self._pos += 1
+        else:
+            if c == '$' or c == ord(b'$'):
+                self._buf[0] = 36
+                self._pos = 1
+
+    def update(self, dat):
+        if not dat:
+            return False
+
+        for i in range(len(dat)):
+            self.update_char(dat[i])
+        return self.valid
+
+    def _time(self, dat):
+        h, m, s = dat[0:2], dat[2:4], dat[4:6]
+        self.time = [int(h), int(m), int(s)]
+        self.datetime[4:7] = self.time
+    
+    def _date(self, dat):
+        d, m, y = dat[0:2], dat[2:4], dat[4:6]
+        self.date = [int(y), int(m), int(d)]
+        self.datetime[0:3] = self.date
+        
+    def _latlon(self, dat):
+        t = float(dat)
+        d, m = divmod(t, 100)
+        return d + m/60
+
+    def _GNGGA(self):
+        self._time(self._seg[1])
+        self.latitude = self._latlon(self._seg[2])
+        self.latitude_dir = self._seg[3].decode()
+        self.longitude = self._latlon(self._seg[4])
+        self.longitude_dir = self._seg[5].decode()
+        self.valid = self._seg[6] in self.GNSS_VALID
+        self.satellites_in_use = int(self._seg[7])
+        self.hdop = float(self._seg[8])
+        self.altitude = float(self._seg[9])
+        self.geoid_height = float(self._seg[11])
+
+    def _GNRMC(self):
+        self._time(self._seg[1])
+        self._date(self._seg[9])
+        self.valid = (self._seg[2] == b'A')
+        self.latitude = self._latlon(self._seg[3])
+        self.latitude_dir = self._seg[4].decode()
+        self.longitude = self._latlon(self._seg[5])
+        self.longitude_dir = self._seg[6].decode()
+        self.speed = float(self._seg[7])
+        self.course = float(self._seg[8])
+
+    def _GNVTG(self):
+        self.course = float(self._seg[1])
+        self.speed = float(self._seg[7])
+
+    def _GNGLL(self):
+        self.latitude = self._latlon(self._seg[1])
+        self.latitude_dir = self._seg[2]
+        self.longitude = self._latlon(self._seg[3])
+        self.longitude_dir = self._seg[4]
+        self._time(self._seg[5])
+        self.valid = (self._seg[6] == b'A')
+    
+    def _GNGSA(self):
+        self.pdop = float(self._seg[15])
+        self.hdop = float(self._seg[16])
+        self.vdop = float(self._seg[17])
+
+    def _GPGSV(self):
+        self.satellites_in_view = int(self._seg[3])
+
+    GNSS_CMD = {
+        b'GNGGA': _GNGGA,
+        b'GNRMC': _GNRMC,
+        b'GNVTG': _GNVTG,
+        b'GNGLL': _GNGLL,
+        b'GPGSV': _GPGSV,
+        b'GNGSA': _GNGSA
+    }
+    
+    def print(self):
+        print('GNSS valid:', self.valid)
+        print('lat:', self.latitude, self.latitude_dir)
+        print('lon:', self.longitude, self.longitude_dir)
+        print('speed:', self.speed)
+        print('altitude:', self.altitude, self.geoid_height)
+        print('hdop:', self.hdop)
+        print('pdop:', self.pdop)
+        print('vdop:', self.vdop)
+        print('UTC:', self.datetime, self.date, self.time)
+        print('satellites')
+        print('  in view:', self.satellites_in_view)
+        print('  in use: ', self.satellites_in_use)
+        print('  list:   ', self.satellites_used)
+