Source Code for Module nxt.compass

 1  # nxt.compass module -- Classes to read Mindsensors Compass sensors 
 2  # Copyright (C) 2006  Douglas P Lau 
 3  # Copyright (C) 2009  Marcus Wanner 
 4  # 
 5  # This program is free software: you can redistribute it and/or modify 
 6  # it under the terms of the GNU General Public License as published by 
 7  # the Free Software Foundation, either version 3 of the License, or 
 8  # (at your option) any later version. 
 9  # 
10  # This program is distributed in the hope that it will be useful, 
11  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
12  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
13  # GNU General Public License for more details. 
14   
15  import sensor 
16  from time import sleep 
17   
18 -class Command(object): 
19          'Namespace for enumeration compass sensor commands' 
20          # NOTE: just a namespace (enumeration) 
21          AUTO_TRIG_ON = (0x41, 0x02) 
22          AUTO_TRIG_OFF = (0x53, 0x01) 
23          MAP_HEADING_BYTE = 0x42         # map heading to 0-255 range 
24          MAP_HEADING_INTEGER = 0x49      # map heading to 0-36000 range 
25          SAMPLING_50_HZ = 0x45           # set sampling frequency to 50 Hz 
26          SAMPLING_60_HZ = 0x55           # set sampling frequency to 60 Hz 
27          SET_ADPA_MODE_ON = 0x4E         # set ADPA mode on 
28          SET_ADPA_MODE_OFF = 0x4F        # set ADPA mode off 
29          BEGIN_CALIBRATION = 0x43        # begin calibration 
30          DONE_CALIBRATION = 0x44         # done with calibration 
31          LOAD_USER_CALIBRATION = 0x4C    # load user calibration value 
32   
33  # I2C addresses for a Mindsensors CMPS-Nx compass sensor 
34  I2C_ADDRESS_CMPS_NX = { 
35          0x41: ('command', 1, True), 
36          0x42: ('heading_lsb', 1, False), 
37          0x43: ('heading_msb', 1, False), 
38          0x44: ('x_offset_lsb', 1, True), 
39          0x45: ('x_offset_msb', 1, True), 
40          0x46: ('y_offset_lsb', 1, True), 
41          0x47: ('y_offset_msb', 1, True), 
42          0x48: ('x_range_lsb', 1, True), 
43          0x49: ('x_range_msb', 1, True), 
44          0x4A: ('y_range_lsb', 1, True), 
45          0x4B: ('y_range_msb', 1, True), 
46          0x4C: ('x_raw_lsb', 1, True), 
47          0x4D: ('x_raw_msb', 1, True), 
48          0x4E: ('y_raw_lsb', 1, True), 
49          0x4F: ('y_raw_msb', 1, True), 
50  } 
51   
52 -class _MetaCMPS_Nx(sensor._Meta): 
53          'Metaclass which adds accessor methods for CMPS-Nx I2C addresses' 
54   
55 -        def __init__(cls, name, bases, dict): 
56                  super(_MetaCMPS_Nx, cls).__init__(name, bases, dict) 
57                  for address in I2C_ADDRESS_CMPS_NX: 
58                          name, n_bytes, set_method = I2C_ADDRESS_CMPS_NX[address] 
59                          q = sensor._make_query(address, n_bytes) 
60                          setattr(cls, 'get_' + name, q) 
61                          if set_method: 
62                                  c = sensor._make_command(address) 
63                                  setattr(cls, 'set_' + name, c) 
64   
65 -class CompassSensor(sensor.DigitalSensor): 
66   
67          __metaclass__ = _MetaCMPS_Nx 
68   
69 -        def __init__(self, brick, port): 
70                  super(CompassSensor, self).__init__(brick, port) 
71                  self.sensor_type = Type.LOW_SPEED_9V 
72                  self.mode = Mode.RAW 
73                  self.set_input_mode() 
74                  sleep(0.1)      # Give I2C time to initialize 
75   
76  CompassSensor.get_sample = CompassSensor.get_heading_lsb 
77