rover/src/tasks/ultrasonic_sensor_sr04_front_task.cpp

/*
 * Copyright (c) 2017 FH Dortmund and others
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Description:
 *    HCSR-04 ultrasonic sensor code with wiringPi and pThreads
 *
 * Authors:
 *    M. Ozcelikors,            R.Hottger
 *    <mozcelikors@gmail.com>   <robert.hoettger@fh-dortmund.de>
 *
 * Contributors:
 *    Resource: https://ninedof.wordpress.com/2013/07/16/rpi-hc-sr04-ultrasonic-sensor-mini-project/
 *
 * Update History:
 *    02.02.2017   -    first compilation
 *    15.03.2017   -    updated tasks for web-based driving
 *    25.03.2017   -    timing library and ultrasonic hcsr-04 added
 *
 */

//Only necessary if you do not use logic level converter:
//A voltage divided should be used and it should be made sure that the grounds are not isolated and are connected to same line.
// ___________
//        +5V|----------------------------> Raspberry Pi +5V Pin
//           |
//           |
//       TRIG|----------------------------> Raspberry Pi BCM-24 Pin
//           |
//           |
//           |                           -----> Connect to Raspberry Pi  BCM-25 Pin
//  HC-SR04  |                           |
//           |                           |
//           |              330 ohm      |     470 ohm
//       ECHO|-------------^^^^^^^^^^--------^^^^^^^^^^--------> Connect to Raspberry Pi GND
//           |
//           |
//        GND|---------------------------------------------------> Connect to Raspberry Pi GND
// __________|


#include <tasks/ultrasonic_sensor_sr04_front_task.h>

#include <ctime>
#include <pthread.h>

#include <libraries/timing/timing.h>
#include <interfaces.h>
#include <pthread.h>

#include <roverapp.h>
#include <roverapi/rover_hcsr04.hpp>

void *Ultrasonic_Sensor_SR04_Front_Task(void *unused)
{
	timing ultrasonic_sr04_front_task_tmr;

	ultrasonic_sr04_front_task_tmr.setTaskID("Ultrasonic_SR04_Front");
	ultrasonic_sr04_front_task_tmr.setDeadline(0.1);
	ultrasonic_sr04_front_task_tmr.setPeriod(0.1);

	RoverHCSR04 r_ultrasonicfront = RoverHCSR04 (ROVER_FRONT);
	r_ultrasonicfront.initialize();

	while (1)
	{
		ultrasonic_sr04_front_task_tmr.recordStartTime();
		ultrasonic_sr04_front_task_tmr.calculatePreviousSlackTime();

		//Task content starts here -----------------------------------------------
		pthread_mutex_lock(&distance_sr04_front_lock);
			distance_sr04_front_shared = r_ultrasonicfront.read();
		pthread_mutex_unlock(&distance_sr04_front_lock);
		//Task content ends here -------------------------------------------------

		ultrasonic_sr04_front_task_tmr.recordEndTime();
		ultrasonic_sr04_front_task_tmr.calculateExecutionTime();
		ultrasonic_sr04_front_task_tmr.calculateDeadlineMissPercentage();
		ultrasonic_sr04_front_task_tmr.incrementTotalCycles();
		pthread_mutex_lock(&ultrasonic_sr04_front_task_ti_l);
			ultrasonic_sr04_front_task_ti.deadline = ultrasonic_sr04_front_task_tmr.getDeadline();
			ultrasonic_sr04_front_task_ti.deadline_miss_percentage = ultrasonic_sr04_front_task_tmr.getDeadlineMissPercentage();
			ultrasonic_sr04_front_task_ti.execution_time = ultrasonic_sr04_front_task_tmr.getExecutionTime();
			ultrasonic_sr04_front_task_ti.period = ultrasonic_sr04_front_task_tmr.getPeriod();
			ultrasonic_sr04_front_task_ti.prev_slack_time = ultrasonic_sr04_front_task_tmr.getPrevSlackTime();
			ultrasonic_sr04_front_task_ti.task_id = ultrasonic_sr04_front_task_tmr.getTaskID();
			ultrasonic_sr04_front_task_ti.start_time = ultrasonic_sr04_front_task_tmr.getStartTime();
			ultrasonic_sr04_front_task_ti.end_time = ultrasonic_sr04_front_task_tmr.getEndTime();
		pthread_mutex_unlock(&ultrasonic_sr04_front_task_ti_l);
		ultrasonic_sr04_front_task_tmr.sleepToMatchPeriod();
	}

	//the function must return something - NULL will do
	return NULL;
}