VEXProRangePublish.cpp

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/*
 * VEXProRangePublish.cpp
 *
 *  Created on: Jul 12, 2012
 *      Author: bouchier
 *
 *  Publish the range from an ultrasonic ranging sensor connected to digital 1 (Input) &
 *  digital 2 (Output) on topic sonar1
 */

#include <ros.h>
#include <std_msgs/Int32.h>
#include <stdio.h>
#include <unistd.h>
#include "qegpioint.h"

ros::NodeHandle  nh;
std_msgs::Int32 range;
ros::Publisher sonar1("sonar1", &range);

char *rosSrvrIp = "192.168.11.9";

#define USPI 150
#define BIAS 300

unsigned long diff(struct timeval *ptv0, struct timeval *ptv1)
{
  long val;

  val = ptv1->tv_usec - ptv0->tv_usec;
  val += (ptv1->tv_sec - ptv0->tv_sec)*1000000;

  return val;
}

void callback(unsigned int io, struct timeval *ptv, void *userdata)
{
  static struct timeval tv0;
  static int flag = 0;
  int sonarVal;

   if (io==0)
     {
       flag = 1;
       tv0 = *ptv;
     }

  if (io==1 && flag)
    {
          sonarVal = diff(&tv0, ptv);
          if (sonarVal>BIAS)
                  sonarVal = (sonarVal-BIAS)/USPI;
          range.data = sonarVal;
      printf("%d\n", sonarVal);
    }
}

// Note: connector labeled "INPUT" on sonar sensor goes to
// digital 1 (bit 0), and connector labeled "OUTPUT" goes to
// digital 2 (bit 1).
int main()
{
  CQEGpioInt &gpio = CQEGpioInt::GetRef();
  volatile unsigned int d;

  // reset bit 0, set as output for sonar trigger
  gpio.SetData(0x0000);
  gpio.SetDataDirection(0x0001);

  // set callbacks on negative edge for both bits 0 (trigger)
  // and 1 (echo)
  gpio.RegisterCallback(0, NULL, callback);
  gpio.RegisterCallback(1, NULL, callback);
  gpio.SetInterruptMode(0, QEG_INTERRUPT_NEGEDGE);
  gpio.SetInterruptMode(1, QEG_INTERRUPT_NEGEDGE);

        //nh.initNode();
        nh.initNode(rosSrvrIp);
        nh.advertise(sonar1);

  // trigger sonar by toggling bit 0
  while(1)
    {
      gpio.SetData(0x0001);
      for (d=0; d<120000; d++);
      gpio.SetData(0x0000);
      sleep(1);         // the interrupt breaks us out of this sleep
      sleep(1);         // now really sleep a second
          sonar1.publish( &range );
          nh.spinOnce();
    }
}