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FRC2016-old/DriveBase/wpilib/cpp/current/include/AnalogTriggerOutput.h
2016-01-28 11:33:19 -05:00

79 lines
3.1 KiB
C++

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2016. 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 "DigitalSource.h"
class AnalogTrigger;
/**
* Class to represent a specific output from an analog trigger.
* This class is used to get the current output value and also as a
* DigitalSource
* to provide routing of an output to digital subsystems on the FPGA such as
* Counter, Encoder, and Interrupt.
*
* The TriggerState output indicates the primary output value of the trigger.
* If the analog
* signal is less than the lower limit, the output is false. If the analog
* value is greater
* than the upper limit, then the output is true. If the analog value is in
* between, then
* the trigger output state maintains its most recent value.
*
* The InWindow output indicates whether or not the analog signal is inside the
* range defined
* by the limits.
*
* The RisingPulse and FallingPulse outputs detect an instantaneous transition
* from above the
* upper limit to below the lower limit, and vise versa. These pulses represent
* a rollover
* condition of a sensor and can be routed to an up / down couter or to
* interrupts. Because
* the outputs generate a pulse, they cannot be read directly. To help ensure
* that a rollover
* condition is not missed, there is an average rejection filter available that
* operates on the
* upper 8 bits of a 12 bit number and selects the nearest outlyer of 3 samples.
* This will reject
* a sample that is (due to averaging or sampling) errantly between the two
* limits. This filter
* will fail if more than one sample in a row is errantly in between the two
* limits. You may see
* this problem if attempting to use this feature with a mechanical rollover
* sensor, such as a
* 360 degree no-stop potentiometer without signal conditioning, because the
* rollover transition
* is not sharp / clean enough. Using the averaging engine may help with this,
* but rotational speeds of
* the sensor will then be limited.
*/
class AnalogTriggerOutput : public DigitalSource {
friend class AnalogTrigger;
public:
virtual ~AnalogTriggerOutput();
bool Get() const;
// DigitalSource interface
virtual uint32_t GetChannelForRouting() const override;
virtual uint32_t GetModuleForRouting() const override;
virtual bool GetAnalogTriggerForRouting() const override;
protected:
AnalogTriggerOutput(const AnalogTrigger &trigger, AnalogTriggerType outputType);
private:
// Uses reference rather than smart pointer because a user can not construct
// an AnalogTriggerOutput themselves and because the AnalogTriggerOutput
// should always be in scope at the same time as an AnalogTrigger.
const AnalogTrigger &m_trigger;
AnalogTriggerType m_outputType;
};