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

135 lines
4.8 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 "SensorBase.h"
#include "LiveWindow/LiveWindowSendable.h"
#include "tables/ITableListener.h"
#include <memory>
/**
* Class implements the PWM generation in the FPGA.
*
* The values supplied as arguments for PWM outputs range from -1.0 to 1.0. They
* are mapped
* to the hardware dependent values, in this case 0-2000 for the FPGA.
* Changes are immediately sent to the FPGA, and the update occurs at the next
* FPGA cycle. There is no delay.
*
* As of revision 0.1.10 of the FPGA, the FPGA interprets the 0-2000 values as
* follows:
* - 2000 = maximum pulse width
* - 1999 to 1001 = linear scaling from "full forward" to "center"
* - 1000 = center value
* - 999 to 2 = linear scaling from "center" to "full reverse"
* - 1 = minimum pulse width (currently .5ms)
* - 0 = disabled (i.e. PWM output is held low)
*/
class PWM : public SensorBase,
public ITableListener,
public LiveWindowSendable {
public:
enum PeriodMultiplier {
kPeriodMultiplier_1X = 1,
kPeriodMultiplier_2X = 2,
kPeriodMultiplier_4X = 4
};
explicit PWM(uint32_t channel);
virtual ~PWM();
virtual void SetRaw(unsigned short value);
virtual unsigned short GetRaw() const;
void SetPeriodMultiplier(PeriodMultiplier mult);
void SetZeroLatch();
void EnableDeadbandElimination(bool eliminateDeadband);
void SetBounds(int32_t max, int32_t deadbandMax, int32_t center,
int32_t deadbandMin, int32_t min);
void SetBounds(double max, double deadbandMax, double center,
double deadbandMin, double min);
uint32_t GetChannel() const { return m_channel; }
protected:
/**
* kDefaultPwmPeriod is in ms
*
* - 20ms periods (50 Hz) are the "safest" setting in that this works for all
* devices
* - 20ms periods seem to be desirable for Vex Motors
* - 20ms periods are the specified period for HS-322HD servos, but work
* reliably down
* to 10.0 ms; starting at about 8.5ms, the servo sometimes hums and get
*hot;
* by 5.0ms the hum is nearly continuous
* - 10ms periods work well for Victor 884
* - 5ms periods allows higher update rates for Luminary Micro Jaguar speed
* controllers.
* Due to the shipping firmware on the Jaguar, we can't run the update
* period less
* than 5.05 ms.
*
* kDefaultPwmPeriod is the 1x period (5.05 ms). In hardware, the period
* scaling is implemented as an
* output squelch to get longer periods for old devices.
*/
static constexpr float kDefaultPwmPeriod = 5.05;
/**
* kDefaultPwmCenter is the PWM range center in ms
*/
static constexpr float kDefaultPwmCenter = 1.5;
/**
* kDefaultPWMStepsDown is the number of PWM steps below the centerpoint
*/
static const int32_t kDefaultPwmStepsDown = 1000;
static const int32_t kPwmDisabled = 0;
virtual void SetPosition(float pos);
virtual float GetPosition() const;
virtual void SetSpeed(float speed);
virtual float GetSpeed() const;
bool m_eliminateDeadband;
int32_t m_maxPwm;
int32_t m_deadbandMaxPwm;
int32_t m_centerPwm;
int32_t m_deadbandMinPwm;
int32_t m_minPwm;
void ValueChanged(ITable* source, llvm::StringRef key,
std::shared_ptr<nt::Value> value, bool isNew) override;
void UpdateTable() override;
void StartLiveWindowMode() override;
void StopLiveWindowMode() override;
std::string GetSmartDashboardType() const override;
void InitTable(std::shared_ptr<ITable> subTable) override;
std::shared_ptr<ITable> GetTable() const override;
std::shared_ptr<ITable> m_table;
private:
uint32_t m_channel;
int32_t GetMaxPositivePwm() const { return m_maxPwm; }
int32_t GetMinPositivePwm() const {
return m_eliminateDeadband ? m_deadbandMaxPwm : m_centerPwm + 1;
}
int32_t GetCenterPwm() const { return m_centerPwm; }
int32_t GetMaxNegativePwm() const {
return m_eliminateDeadband ? m_deadbandMinPwm : m_centerPwm - 1;
}
int32_t GetMinNegativePwm() const { return m_minPwm; }
int32_t GetPositiveScaleFactor() const {
return GetMaxPositivePwm() - GetMinPositivePwm();
} ///< The scale for positive speeds.
int32_t GetNegativeScaleFactor() const {
return GetMaxNegativePwm() - GetMinNegativePwm();
} ///< The scale for negative speeds.
int32_t GetFullRangeScaleFactor() const {
return GetMaxPositivePwm() - GetMinNegativePwm();
} ///< The scale for positions.
};