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scoutos / scout / encoders / src / encoders.cpp @ 126fea96

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/**
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 * Copyright (c) 2011 Colony Project
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 * 
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 * Permission is hereby granted, free of charge, to any person
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 * obtaining a copy of this software and associated documentation
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 * files (the "Software"), to deal in the Software without
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 * restriction, including without limitation the rights to use,
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 * copy, modify, merge, publish, distribute, sublicense, and/or sell
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 * copies of the Software, and to permit persons to whom the
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 * Software is furnished to do so, subject to the following
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 * conditions:
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 * 
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 * The above copyright notice and this permission notice shall be
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 * included in all copies or substantial portions of the Software.
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 * 
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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 * OTHER DEALINGS IN THE SOFTWARE.
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 */
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/**
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 * @file encoders.cpp
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 * @brief Encoders
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 *
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 * Implementation of functions for encoder use.
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 *
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 * @author Colony Project, CMU Robotics Club
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 * @author Alex Zirbel
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 * @author Tom Mullins
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 * @defgroup encoders Encoders
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 * @brief Functions for using the encoders
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 *
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 * @{
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 **/
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#include <ros/ros.h>
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#include "encoders.h"
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/* Encoder instances */
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/* @todo make sure these are the correct numbers */
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static Encoder encoder_fl(0);
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static Encoder encoder_fr(1);
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static Encoder encoder_bl(2);
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static Encoder encoder_br(3);
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/**
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 * @brief Encoder constructor
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 *
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 * Opens device file, which is read at every call to get_ticks
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 *
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 * @param n The encoder number to read, between 0 and 3 inclusive
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 */
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Encoder::Encoder(int n)
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{
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    sprintf(filename, "/sys/class/encoder/enc%d/ticks", n);
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}
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/**
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 * @brief Returns the current tick count
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 *
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 * This will actually read from the encoder ticks file to get the latest value
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 * from the driver
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 */
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int Encoder::get_ticks()
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{
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    // open device file
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    fticks.open(filename, std::ios::in);
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    int ticks;
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    fticks >> ticks;
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    fticks.close();
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    return ticks;
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}
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/**
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 * @brief Outputs current encoder data
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 *
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 * Serves the service query_encoders by responding to service requests with the
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 * encoder values.
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 * @param req The request. The units that the response should be in.
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 * @param res The response. The fields will be filled with values.
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 */
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bool handle_encoders_query(::messages::query_encoders::Request  &req,
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                           ::messages::query_encoders::Response &res)
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{
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    /* Put index, velocity, and distance data in message */
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    res.fl_distance = encoder_fl.get_ticks();
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    res.fr_distance = encoder_fr.get_ticks();
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    res.bl_distance = encoder_bl.get_ticks();
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    res.br_distance = encoder_br.get_ticks();
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    /* @todo maybe return value based on whether reads succeeded */
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    ROS_DEBUG("Encoder values queried");
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    ROS_INFO("Encoder values queried %d  %d  %d   %d", res.fl_distance, res.fr_distance, res.bl_distance, res.br_distance);
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    return true;
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}
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/**
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 * @brief Encoders driver. This is a ROS node that controls encoders.
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 *
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 * This is the main function for the encoders node. It is run when the node
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 * starts and initializes the encoders. It then publishes to the
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 * encoder_state topic and advertises the query_encoders service.
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 */
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int main(int argc, char **argv)
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{
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    /* Initialize in ROS the encoders driver node */
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    ros::init(argc, argv, "encoders_driver");
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    /* Advertise that this serves the query_encoders service */
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    ros::NodeHandle n;
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    ros::ServiceServer service =
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        n.advertiseService("query_encoders",
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                           handle_encoders_query);
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    ROS_INFO("Ready to set encoders.");
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    ros::spin();
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    return 0;
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}
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/** @} */