| jerrym | f157933 | 2013-02-07 01:56:28 +0000 | [diff] [blame] | 1 | /*----------------------------------------------------------------------------*/
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| 2 | /* Copyright (c) FIRST 2008. All Rights Reserved. */
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| 3 | /* Open Source Software - may be modified and shared by FRC teams. The code */
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| 4 | /* must be accompanied by the FIRST BSD license file in $(WIND_BASE)/WPILib. */
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| 5 | /*----------------------------------------------------------------------------*/
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| 6 |
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| 7 | #ifndef ANALOG_TRIGGER_OUTPUT_H_
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| 8 | #define ANALOG_TRIGGER_OUTPUT_H_
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| 9 |
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| 10 | #include "DigitalSource.h"
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| 11 |
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| 12 | class AnalogTrigger;
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| 13 |
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| 14 | /**
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| 15 | * Class to represent a specific output from an analog trigger.
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| 16 | * This class is used to get the current output value and also as a DigitalSource
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| 17 | * to provide routing of an output to digital subsystems on the FPGA such as
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| 18 | * Counter, Encoder, and Interrupt.
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| 19 | *
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| 20 | * The TriggerState output indicates the primary output value of the trigger. If the analog
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| 21 | * signal is less than the lower limit, the output is false. If the analog value is greater
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| 22 | * than the upper limit, then the output is true. If the analog value is in between, then
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| 23 | * the trigger output state maintains its most recent value.
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| 24 | *
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| 25 | * The InWindow output indicates whether or not the analog signal is inside the range defined
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| 26 | * by the limits.
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| 27 | *
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| 28 | * The RisingPulse and FallingPulse outputs detect an instantaneous transition from above the
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| 29 | * upper limit to below the lower limit, and vise versa. These pulses represent a rollover
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| 30 | * condition of a sensor and can be routed to an up / down couter or to interrupts. Because
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| 31 | * the outputs generate a pulse, they cannot be read directly. To help ensure that a rollover
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| 32 | * condition is not missed, there is an average rejection filter available that operates on the
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| 33 | * upper 8 bits of a 12 bit number and selects the nearest outlyer of 3 samples. This will reject
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| 34 | * a sample that is (due to averaging or sampling) errantly between the two limits. This filter
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| 35 | * will fail if more than one sample in a row is errantly in between the two limits. You may see
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| 36 | * this problem if attempting to use this feature with a mechanical rollover sensor, such as a
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| 37 | * 360 degree no-stop potentiometer without signal conditioning, because the rollover transition
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| 38 | * is not sharp / clean enough. Using the averaging engine may help with this, but rotational speeds of
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| 39 | * the sensor will then be limited.
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| 40 | */
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| 41 | class AnalogTriggerOutput: public DigitalSource
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| 42 | {
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| 43 | friend class AnalogTrigger;
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| 44 | public:
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| 45 | typedef enum {kInWindow=0, kState=1, kRisingPulse=2, kFallingPulse=3} Type;
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| 46 |
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| 47 | virtual ~AnalogTriggerOutput();
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| 48 | bool Get();
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| 49 |
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| 50 | // DigitalSource interface
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| 51 | virtual UINT32 GetChannelForRouting();
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| 52 | virtual UINT32 GetModuleForRouting();
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| 53 | virtual bool GetAnalogTriggerForRouting();
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| 54 | virtual void RequestInterrupts(tInterruptHandler handler, void *param=NULL); ///< Asynchronus handler version.
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| 55 | virtual void RequestInterrupts(); ///< Synchronus Wait version.
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| 56 | protected:
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| 57 | AnalogTriggerOutput(AnalogTrigger *trigger, Type outputType);
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| 58 |
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| 59 | private:
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| 60 | AnalogTrigger *m_trigger;
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| 61 | Type m_outputType;
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| 62 | };
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| 63 |
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| 64 |
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| 65 | #endif
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