wiring_analog.c File Reference

Analog input (ADC) and analog output (PWM or DAC) functions. More...

#include "Arduino.h"
#include "PinConfigured.h"

Macros
#define	MAX_PWM_RESOLUTION   16
#define	MAX_ADC_RESOLUTION   12

Functions
static uint32_t	mapResolution (uint32_t value, uint32_t from, uint32_t to)
	Map a value from one resolution to another.
void	analogReadResolution (int res)
	Set the resolution of analogRead return values.
void	analogReference (uint8_t mode)
	Set the analog reference voltage.
int	analogRead (pin_size_t pinNumber)
	Read the analog value of a pin, scaled to the resolution set by analogReadResolution().
void	analogWriteResolution (int res)
	Set the resolution of analogWrite parameters.
void	analogWriteFrequency (uint32_t freq)
	Set the frequency of analogWrite.
void	analogWrite (pin_size_t pinNumber, int value)
	Write an analog value to a pin, using PWM or DAC if the pin supports it.

Variables
uint32_t	g_anOutputPinConfigured [MAX_NB_PORT] = {0}
static int	_writeResolution = PWM_RESOLUTION
static int	_internalWriteResolution
static uint32_t	_writeFreq = PWM_FREQUENCY
static int	_readResolution = ADC_RESOLUTION
static int	_internalReadResolution

Detailed Description

Analog input (ADC) and analog output (PWM or DAC) functions.

Function Documentation

analogRead()

int analogRead

(

pin_size_t

pinNumber

)

Read the analog value of a pin, scaled to the resolution set by analogReadResolution().

The initialization of the analog pin is done through this function.

Parameters

pinNumber

Analog pin number, e.g. A0 or PA0.

Returns

Converted value, between 0 and 2^resolution - 1. 0 if the pin has no ADC.

analogReadResolution()

void analogReadResolution

(

int

res

)

Set the resolution of analogRead return values.

Default is 10 bits (range from 0 to 1023).

Note

The ADC is configured with the closest supported hardware resolution (capped to the maximum of the ADC) and the result is scaled to the requested resolution. Values outside the range 1 to 32 call Error_Handler().

See also

analogRead(), analogWriteResolution()

Parameters

res	Number of bits of the resolution, from 1 to 32.

analogReference()

void analogReference

(

uint8_t

mode

)

Set the analog reference voltage.

Not supported on this core, the call has no effect.

Parameters

mode	Reference mode, ignored.

analogWrite()

void analogWrite	(	pin_size_t	pinNumber,
		int	value
	)

Write an analog value to a pin, using PWM or DAC if the pin supports it.

Output only works on the pins with Hardware Timer (PWM) or DAC support. For the other pins, it defaults to digital output: the value is scaled to 8 bits and the pin is set HIGH if it is 128 or more, LOW otherwise. The DAC takes precedence over PWM when a pin supports both.

Parameters

pinNumber	Pin number to write to.
value	Value to write, scaled to the resolution set by analogWriteResolution().

analogWriteFrequency()

void analogWriteFrequency

(

uint32_t

freq

)

Set the frequency of analogWrite.

Default is PWM_FREQUENCY (1000) in Hertz.

See also

analogWrite(), analogWriteResolution()

Parameters

freq	PWM frequency in Hertz.

analogWriteResolution()

void analogWriteResolution

(

int

res

)

Set the resolution of analogWrite parameters.

Default is 8 bits (range from 0 to 255).

Note

The PWM hardware resolution is capped to 16 bits and the value is scaled accordingly. Values outside the range 1 to 32 call Error_Handler().

See also

analogWrite(), analogReadResolution(), analogWriteFrequency()

Parameters

res	Number of bits of the resolution, from 1 to 32.

mapResolution()

static uint32_t mapResolution ( uint32_t  value, uint32_t  from, uint32_t  to  )

inlinestatic

Map a value from one resolution to another.

Parameters

value	Value to convert.
from	Resolution of value, in bits.
to	Target resolution, in bits.

Returns

Value scaled to the target resolution.

Variable Documentation

_internalReadResolution

int _internalReadResolution

static

Initial value:

=
 
 
 
 
 
 
 
 
 
 
  12

_internalWriteResolution

int _internalWriteResolution

static

Initial value:

=
 
 
 
  PWM_RESOLUTION