Files
allwpilib/wpilibc/src/main/native/include/frc/Ultrasonic.h
Peter Johnson a9f0e46680 Implement sim devices for ADXL345, ADXL362, ADXRS450, Ultrasonic
This makes the halsim_adx_gyro_accelerometer simulation plugin and
the accelerometer part of lowfi_simulation obsolete.
2019-10-05 22:39:00 -07:00

242 lines
8.5 KiB
C++

/*----------------------------------------------------------------------------*/
/* Copyright (c) 2008-2019 FIRST. All Rights Reserved. */
/* Open Source Software - may be modified and shared by FRC teams. The code */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project. */
/*----------------------------------------------------------------------------*/
#pragma once
#include <atomic>
#include <memory>
#include <thread>
#include <vector>
#include <hal/SimDevice.h>
#include "frc/Counter.h"
#include "frc/ErrorBase.h"
#include "frc/PIDSource.h"
#include "frc/smartdashboard/Sendable.h"
#include "frc/smartdashboard/SendableHelper.h"
namespace frc {
class DigitalInput;
class DigitalOutput;
/**
* Ultrasonic rangefinder class.
*
* The Ultrasonic rangefinder measures absolute distance based on the round-trip
* time of a ping generated by the controller. These sensors use two
* transducers, a speaker and a microphone both tuned to the ultrasonic range. A
* common ultrasonic sensor, the Daventech SRF04 requires a short pulse to be
* generated on a digital channel. This causes the chirp to be emitted. A second
* line becomes high as the ping is transmitted and goes low when the echo is
* received. The time that the line is high determines the round trip distance
* (time of flight).
*/
class Ultrasonic : public ErrorBase,
public Sendable,
public PIDSource,
public SendableHelper<Ultrasonic> {
public:
enum DistanceUnit { kInches = 0, kMilliMeters = 1 };
/**
* Create an instance of the Ultrasonic Sensor.
*
* This is designed to support the Daventech SRF04 and Vex ultrasonic sensors.
*
* @param pingChannel The digital output channel that sends the pulse to
* initiate the sensor sending the ping.
* @param echoChannel The digital input channel that receives the echo. The
* length of time that the echo is high represents the
* round trip time of the ping, and the distance.
* @param units The units returned in either kInches or kMilliMeters
*/
Ultrasonic(int pingChannel, int echoChannel, DistanceUnit units = kInches);
/**
* Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo
* channel and a DigitalOutput for the ping channel.
*
* @param pingChannel The digital output object that starts the sensor doing a
* ping. Requires a 10uS pulse to start.
* @param echoChannel The digital input object that times the return pulse to
* determine the range.
* @param units The units returned in either kInches or kMilliMeters
*/
Ultrasonic(DigitalOutput* pingChannel, DigitalInput* echoChannel,
DistanceUnit units = kInches);
/**
* Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo
* channel and a DigitalOutput for the ping channel.
*
* @param pingChannel The digital output object that starts the sensor doing a
* ping. Requires a 10uS pulse to start.
* @param echoChannel The digital input object that times the return pulse to
* determine the range.
* @param units The units returned in either kInches or kMilliMeters
*/
Ultrasonic(DigitalOutput& pingChannel, DigitalInput& echoChannel,
DistanceUnit units = kInches);
/**
* Create an instance of an Ultrasonic Sensor from a DigitalInput for the echo
* channel and a DigitalOutput for the ping channel.
*
* @param pingChannel The digital output object that starts the sensor doing a
* ping. Requires a 10uS pulse to start.
* @param echoChannel The digital input object that times the return pulse to
* determine the range.
* @param units The units returned in either kInches or kMilliMeters
*/
Ultrasonic(std::shared_ptr<DigitalOutput> pingChannel,
std::shared_ptr<DigitalInput> echoChannel,
DistanceUnit units = kInches);
~Ultrasonic() override;
Ultrasonic(Ultrasonic&&) = default;
Ultrasonic& operator=(Ultrasonic&&) = default;
/**
* Single ping to ultrasonic sensor.
*
* Send out a single ping to the ultrasonic sensor. This only works if
* automatic (round robin) mode is disabled. A single ping is sent out, and
* the counter should count the semi-period when it comes in. The counter is
* reset to make the current value invalid.
*/
void Ping();
/**
* Check if there is a valid range measurement.
*
* The ranges are accumulated in a counter that will increment on each edge of
* the echo (return) signal. If the count is not at least 2, then the range
* has not yet been measured, and is invalid.
*/
bool IsRangeValid() const;
/**
* Turn Automatic mode on/off.
*
* When in Automatic mode, all sensors will fire in round robin, waiting a set
* time between each sensor.
*
* @param enabling Set to true if round robin scheduling should start for all
* the ultrasonic sensors. This scheduling method assures that
* the sensors are non-interfering because no two sensors fire
* at the same time. If another scheduling algorithm is
* prefered, it can be implemented by pinging the sensors
* manually and waiting for the results to come back.
*/
static void SetAutomaticMode(bool enabling);
/**
* Get the range in inches from the ultrasonic sensor.
*
* @return Range in inches of the target returned from the ultrasonic sensor.
* If there is no valid value yet, i.e. at least one measurement
* hasn't completed, then return 0.
*/
double GetRangeInches() const;
/**
* Get the range in millimeters from the ultrasonic sensor.
*
* @return Range in millimeters of the target returned by the ultrasonic
* sensor. If there is no valid value yet, i.e. at least one
* measurement hasn't completed, then return 0.
*/
double GetRangeMM() const;
bool IsEnabled() const;
void SetEnabled(bool enable);
/**
* Set the current DistanceUnit that should be used for the PIDSource base
* object.
*
* @param units The DistanceUnit that should be used.
*/
void SetDistanceUnits(DistanceUnit units);
/**
* Get the current DistanceUnit that is used for the PIDSource base object.
*
* @return The type of DistanceUnit that is being used.
*/
DistanceUnit GetDistanceUnits() const;
/**
* Get the range in the current DistanceUnit for the PIDSource base object.
*
* @return The range in DistanceUnit
*/
double PIDGet() override;
void SetPIDSourceType(PIDSourceType pidSource) override;
void InitSendable(SendableBuilder& builder) override;
private:
/**
* Initialize the Ultrasonic Sensor.
*
* This is the common code that initializes the ultrasonic sensor given that
* there are two digital I/O channels allocated. If the system was running in
* automatic mode (round robin) when the new sensor is added, it is stopped,
* the sensor is added, then automatic mode is restored.
*/
void Initialize();
/**
* Background task that goes through the list of ultrasonic sensors and pings
* each one in turn. The counter is configured to read the timing of the
* returned echo pulse.
*
* DANGER WILL ROBINSON, DANGER WILL ROBINSON:
* This code runs as a task and assumes that none of the ultrasonic sensors
* will change while it's running. Make sure to disable automatic mode before
* touching the list.
*/
static void UltrasonicChecker();
// Time (sec) for the ping trigger pulse.
static constexpr double kPingTime = 10 * 1e-6;
// Priority that the ultrasonic round robin task runs.
static constexpr int kPriority = 64;
// Max time (ms) between readings.
static constexpr double kMaxUltrasonicTime = 0.1;
static constexpr double kSpeedOfSoundInchesPerSec = 1130.0 * 12.0;
// Thread doing the round-robin automatic sensing
static std::thread m_thread;
// Ultrasonic sensors
static std::vector<Ultrasonic*> m_sensors;
// Automatic round-robin mode
static std::atomic<bool> m_automaticEnabled;
std::shared_ptr<DigitalOutput> m_pingChannel;
std::shared_ptr<DigitalInput> m_echoChannel;
bool m_enabled = false;
Counter m_counter;
DistanceUnit m_units;
hal::SimDevice m_simDevice;
hal::SimBoolean m_simRangeValid;
hal::SimDouble m_simRange;
};
} // namespace frc