Statistics
| Branch: | Revision:

root / scout / encoders / src / encoders.cpp @ 259aaff8

History | View | Annotate | Download (3.81 KB)

1 14241f84 Lalitha Ganesan
/**
2
 * Copyright (c) 2011 Colony Project
3
 * 
4
 * Permission is hereby granted, free of charge, to any person
5
 * obtaining a copy of this software and associated documentation
6
 * files (the "Software"), to deal in the Software without
7
 * restriction, including without limitation the rights to use,
8
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
9
 * copies of the Software, and to permit persons to whom the
10
 * Software is furnished to do so, subject to the following
11
 * conditions:
12
 * 
13
 * The above copyright notice and this permission notice shall be
14
 * included in all copies or substantial portions of the Software.
15
 * 
16
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
18
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
20
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
21
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
23
 * OTHER DEALINGS IN THE SOFTWARE.
24 c492be62 Alex Zirbel
 */
25 14241f84 Lalitha Ganesan
26
/**
27
 * @file encoders.cpp
28
 * @brief Encoders
29
 *
30
 * Implementation of functions for encoder use.
31
 *
32
 * @author Colony Project, CMU Robotics Club
33 ce559b91 Alex Zirbel
 * @author Alex Zirbel
34 d7c3c222 Tom Mullins
 * @author Tom Mullins
35 14241f84 Lalitha Ganesan
 **/
36
37 ce559b91 Alex Zirbel
#include <ros/ros.h>
38 14241f84 Lalitha Ganesan
#include "encoders.h"
39
40
/**
41
 * @defgroup encoders Encoders
42
 * @brief Functions for using the encoders
43
 *
44 ce559b91 Alex Zirbel
 * @{
45
 */
46 14241f84 Lalitha Ganesan
47 d7c3c222 Tom Mullins
/* Encoder instances */
48
/* @todo make sure these are the correct numbers */
49
static Encoder encoder_fl(0);
50
static Encoder encoder_fr(1);
51
static Encoder encoder_bl(2);
52
static Encoder encoder_br(3);
53 ce559b91 Alex Zirbel
54 d7c3c222 Tom Mullins
/**
55
 * @brief Encoder constructor
56
 *
57
 * Opens device file, which is read at every call to get_ticks
58
 *
59
 * @param n The encoder number to read, between 0 and 3 inclusive
60
 */
61
Encoder::Encoder(int n)
62
{
63 f358d0b2 Colony Scout
    sprintf(filename, "/sys/class/encoder/enc%d/ticks", n);
64 d7c3c222 Tom Mullins
}
65
66
/**
67
 * @brief Returns the current tick count
68
 *
69
 * This will actually read from the encoder ticks file to get the latest value
70
 * from the driver
71
 */
72
int Encoder::get_ticks()
73
{
74 f358d0b2 Colony Scout
    // open device file
75
    fticks.open(filename, std::ios::in);
76
77 d7c3c222 Tom Mullins
    int ticks;
78
    fticks >> ticks;
79 f358d0b2 Colony Scout
80
    fticks.close();
81 d7c3c222 Tom Mullins
    return ticks;
82
}
83 7cb5de78 Ben Wasserman
84 ce559b91 Alex Zirbel
/**
85
 * @brief Outputs current encoder data
86
 *
87
 * Serves the service query_encoders by responding to service requests with the
88
 * encoder values.
89
 * @param req The request. The units that the response should be in.
90
 * @param res The response. The fields will be filled with values.
91
 */
92 6ebee82c Alex
bool handle_encoders_query(::messages::query_encoders::Request  &req,
93
                           ::messages::query_encoders::Response &res)
94 ce559b91 Alex Zirbel
{
95
    /* Put index, velocity, and distance data in message */
96 259aaff8 Colony Scout
    res.fl_distance = -encoder_fl.get_ticks();
97 d7c3c222 Tom Mullins
    res.fr_distance = encoder_fr.get_ticks();
98
    res.bl_distance = encoder_bl.get_ticks();
99
    res.br_distance = encoder_br.get_ticks();
100 ce559b91 Alex Zirbel
101 d7c3c222 Tom Mullins
    /* @todo maybe return value based on whether reads succeeded */
102
103
    ROS_DEBUG("Encoder values queried");
104 f358d0b2 Colony Scout
    ROS_INFO("Encoder values queried %d  %d  %d   %d", res.fl_distance, res.fr_distance, res.bl_distance, res.br_distance);
105 ce559b91 Alex Zirbel
    return true;
106
}
107 14241f84 Lalitha Ganesan
108 ce559b91 Alex Zirbel
/**
109
 * @brief Encoders driver. This is a ROS node that controls encoders.
110 14241f84 Lalitha Ganesan
 *
111
 * This is the main function for the encoders node. It is run when the node
112
 * starts and initializes the encoders. It then publishes to the
113
 * encoder_state topic and advertises the query_encoders service.
114 ce559b91 Alex Zirbel
 */
115
int main(int argc, char **argv)
116
{
117
    /* Initialize in ROS the encoders driver node */
118
    ros::init(argc, argv, "encoders_driver");
119 14241f84 Lalitha Ganesan
120 ce559b91 Alex Zirbel
    /* Advertise that this serves the query_encoders service */
121
    ros::NodeHandle n;
122
    ros::ServiceServer service =
123
        n.advertiseService("query_encoders",
124
                           handle_encoders_query);
125 14241f84 Lalitha Ganesan
126 ce559b91 Alex Zirbel
    ROS_INFO("Ready to set encoders.");
127 14241f84 Lalitha Ganesan
128 ce559b91 Alex Zirbel
    ros::spin();
129 14241f84 Lalitha Ganesan
130 ce559b91 Alex Zirbel
    return 0;
131 14241f84 Lalitha Ganesan
}
132
133 ce559b91 Alex Zirbel
/** @} */