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