FilteredAnalog< Precision, FilterShiftFactor, FilterType, AnalogType, IncRes > Class Template Reference

A class that reads and filters an analog input. More...

#include <AH/Hardware/FilteredAnalog.hpp>

Collaboration diagram for FilteredAnalog< Precision, FilterShiftFactor, FilterType, AnalogType, IncRes >:

Public Types
using	MappingFunction = AnalogType(*)(AnalogType)
	A function pointer to a mapping function to map analog values. More...

Public Member Functions
	FilteredAnalog (pin_t analogPin)
	Construct a new FilteredAnalog object. More...
void	map (MappingFunction fn)
	Specify a mapping function that is applied to the raw analog value before filtering. More...
void	invert ()
	Invert the analog value. More...
bool	update ()
	Read the analog input value, apply the mapping function, and update the average. More...
AnalogType	getValue () const
	Get the filtered value of the analog input (with the mapping function applied). More...
float	getFloatValue () const
	Get the filtered value of the analog input with the mapping function applied as a floating point number from 0.0 to 1.0. More...
AnalogType	getRawValue () const
	Read the raw value of the analog input any filtering or mapping applied, but with its bit depth increased by IncRes. More...

Static Public Member Functions
static void	setupADC ()
	Select the configured ADC resolution. More...

Private Attributes
const pin_t	analogPin
MappingFunction	mapFn = nullptr
EMA< FilterShiftFactor, FilterType >	filter
Hysteresis< ADC_BITS+IncRes - Precision, AnalogType, AnalogType >	hysteresis

Detailed Description

template<uint8_t Precision = 10, uint8_t FilterShiftFactor = ANALOG_FILTER_SHIFT_FACTOR, class FilterType = ANALOG_FILTER_TYPE, class AnalogType = analog_t, uint8_t IncRes = min(sizeof(FilterType) * CHAR_BIT - ADC_BITS - FilterShiftFactor, sizeof(AnalogType) * CHAR_BIT - ADC_BITS)>
class AH::FilteredAnalog< Precision, FilterShiftFactor, FilterType, AnalogType, IncRes >

A class that reads and filters an analog input.

A map function can be applied to the analog value (e.g. to compensate for logarithmic taper potentiometers or to calibrate the range). The analog input value is filtered using an exponential moving average filter. The default settings for this filter can be changed in Settings.hpp.
After filtering, hysteresis is applied to prevent flipping back and forth between two values when the input is not changing.

Template Parameters

Precision	The number of bits of precision the output should have.
FilterShiftFactor	The number of bits used for the EMA filter. The pole location is \( 1 - \left(\frac{1}{2}\right)^{\text{FilterShiftFactor}} \). A lower shift factor means less filtering ( \(0\) is no filtering), and a higher shift factor means more filtering (and more latency).
FilterType	The type to use for the intermediate types of the filter. Should be at least \( \text{ADC_BITS} + \text{IncRes} + \text{FilterShiftFactor} \) bits wide.
AnalogType	The type to use for the analog values. Should be at least \( \text{ADC_BITS} + \text{IncRes} \) bits wide.
IncRes	The number of bits to increase the resolution of the analog reading by.

Definition at line 55 of file FilteredAnalog.hpp.

Member Typedef Documentation

MappingFunction

using MappingFunction = AnalogType (*)(AnalogType)

A function pointer to a mapping function to map analog values.

See also

map()

Definition at line 67 of file FilteredAnalog.hpp.

Constructor & Destructor Documentation

FilteredAnalog()

FilteredAnalog ( pin_t  analogPin )

inline

Construct a new FilteredAnalog object.

Parameters

analogPin

The analog pin to read from.

Definition at line 63 of file FilteredAnalog.hpp.

Member Function Documentation

map()

void map ( MappingFunction  fn )

inline

Specify a mapping function that is applied to the raw analog value before filtering.

Parameters

fn	A function pointer to the mapping function. This function should take the filtered value (of ADC_BITS + IncRes bits wide) as a parameter, and should return a value of ADC_BITS + IncRes bits wide.

Note

Applying the mapping function before filtering could result in the noise being amplified to such an extent that filtering it afterwards would be ineffective.
Applying it after hysteresis would result in a lower resolution.
That's why the mapping function is applied after filtering and before hysteresis.

Definition at line 86 of file FilteredAnalog.hpp.

invert()

void invert ( )

inline

Invert the analog value.

For example, if the precision is 10 bits, when the analog input measures 1023, the output will be 0, and when the analog input measures 0, the output will be 1023.

Note

This overrides the mapping function set by the map method.

Definition at line 95 of file FilteredAnalog.hpp.

update()

bool update ( )

inline

Read the analog input value, apply the mapping function, and update the average.

Return values

true	The value changed since last time it was updated.
false	The value is still the same.

Definition at line 109 of file FilteredAnalog.hpp.

getValue()

AnalogType getValue ( ) const

inline

Get the filtered value of the analog input (with the mapping function applied).

Note

This function just returns the value from the last call to update, it doesn't read the analog input again.

Returns

The filtered value of the analog input, as a number of Precision bits wide.

Definition at line 128 of file FilteredAnalog.hpp.

getFloatValue()

float getFloatValue ( ) const

inline

Get the filtered value of the analog input with the mapping function applied as a floating point number from 0.0 to 1.0.

Returns

The filtered value of the analog input, as a number from 0.0 to 1.0.

Definition at line 137 of file FilteredAnalog.hpp.

getRawValue()

AnalogType getRawValue ( ) const

inline

Read the raw value of the analog input any filtering or mapping applied, but with its bit depth increased by IncRes.

Definition at line 145 of file FilteredAnalog.hpp.

setupADC()

static void setupADC ( )

inlinestatic

Select the configured ADC resolution.

By default, it is set to the maximum resolution supported by the hardware.

See also

ADC_BITS

ADCConfig.hpp

Definition at line 157 of file FilteredAnalog.hpp.

Member Data Documentation

analogPin

const pin_t analogPin

private

Definition at line 164 of file FilteredAnalog.hpp.

mapFn

MappingFunction mapFn = nullptr

private

Definition at line 166 of file FilteredAnalog.hpp.

filter

EMA<FilterShiftFactor, FilterType> filter

private

Definition at line 170 of file FilteredAnalog.hpp.

hysteresis

Hysteresis<ADC_BITS + IncRes - Precision, AnalogType, AnalogType> hysteresis

private

Definition at line 180 of file FilteredAnalog.hpp.

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The documentation for this class was generated from the following file:

• FilteredAnalog.hpp