Class supporting thermistor measurements. More...

#include <nrfcxx/sensor/adc.hpp>

Inheritance diagram for nrfcxx::sensor::adc::ntcThermistor:

Public Member Functions
template<typename Iterator >
	ntcThermistor (Iterator ains_begin, Iterator ains_end, volatile uint16_t raw=nullptr, const SteinhartHart coeff=&steinhartHart::adafruit372fullScale, unsigned int ref_Ohm=10000)
	Generic constructor for an iterable set of thermistor channels and optional external storage. More...

	ntcThermistor (std::initializer_list< uint8_t > ains, volatile uint16_t raw=nullptr, const SteinhartHart coeff=&steinhartHart::adafruit372fullScale, unsigned int ref_Ohm=10000)
	Constructor for an explicit list of channels.

int	convert_adc16_cCel (unsigned int therm_adc16)
	Convert a measured voltage to a temperature. More...

int	temperature_cCel (size_t ci=0)
	Convert the stored measured voltage to a thermisor. More...

unsigned int	therm_adc16 (size_t ci=0) const
	Return the last raw 16-bit ADC thermistor reading.

unsigned int	therm_Ohm (size_t ci=0) const
	Return the estimated thermistor resistance, in Ohms.

Public Member Functions inherited from nrfcxx::sensor::adc::voltage_divider
template<typename Iterator >
	voltage_divider (unsigned int r1_Ohm, unsigned int r2_Ohm, Iterator ains_begin, Iterator ains_end, volatile uint16_t *raw=nullptr)
	Generic constructor for an iterable set of channels and optional external storage. More...

	voltage_divider (unsigned int r1_Ohm, unsigned int r2_Ohm, uint8_t ain)
	Constructor for common case of a single channel with internal storage.

	voltage_divider (unsigned int r1_Ohm, unsigned int r2_Ohm, std::initializer_list< uint8_t > ains, volatile uint16_t *raw=nullptr)
	Constructor for an explicit list of channels.

size_t	count () const
	The number of channels used by this client.

int	channel_ain (size_t ci) const
	Extract the channel associated with the provided index. More...

int	sample_adc16 (size_t ci=0) const
	Retrieve the latest raw measurement for a channel. More...

int	sample_mV (size_t ci=0, bool truncate=false) const
	Retrieve the latest output voltage measurement for a channel. More...

int	input_mV (size_t ci=0) const
	Retrieve the latest input voltage measurement for a channel. More...

virtual int	measurement_mV (uint16_t m16) const
	Convert a raw ADC measurement to mV. More...

int	measurement_Ohm (uint16_t m16) const
	Convert a raw ADC measurement to the estimated resistance. More...

int	sample_Ohm (size_t ci=0, bool filter_high_negative=false) const
	Retrieve the latest estimated resistance for a channel. More...

Public Member Functions inherited from nrfcxx::periph::ADCClient
virtual	~ADCClient ()
	Release the peripheral when the client is destructed.

int	claim ()
	Attempt to claim exclusive use of the ADC peripheral. More...

int	release ()
	Release the ADC peripheral. More...

int	calibrate (const notifier_type &notify={})
	Calibrate the ADC. More...

virtual int	sample_setup ()
	Overridable function to set up for an ADC measurement. More...

virtual void	sample_teardown ()
	Reverse the effects of sample_setup_(). More...

int	sample (const notifier_type &notify={})
	Trigger a client-specific collection. More...

int	queue (const notifier_type &notify, const queued_callback_type &qnotify={}, bool calibrate=false)
	Queue an operation to be initiated as soon as the ADC becomes available. More...

int	queue (bool calibrate=false)
	Overload when no notifications are required. More...

Data Fields
const SteinhartHart *const	steinhartHart
	The Steinhart-Hart coefficients and extreme values for the thermistor in the circuit.

Data Fields inherited from nrfcxx::sensor::adc::voltage_divider
const unsigned int	r1_Ohm
	The resistance of the upper leg of the voltage divider, connected to the input voltage. More...

const unsigned int	r2_Ohm
	The resistance of the lower leg of the voltage divider, connected to ground. More...

volatile uint16_t *	ptr

uint16_t volatile	val [MAX_INTERNAL]

Static Public Attributes
static constexpr int	ABSOLUTE_ZERO_cCel = -27315
	Constant used to convert between Kelvin and Celsius.

static constexpr int	INVALID_cCel = 30000
	An flag value for invalid temperatures. More...

static constexpr int	SHORT_cCel = INVALID_cCel + 1
	Measurement returned by temperature_cCel() for a shorted thermistor. More...

static constexpr int	OPEN_cCel = - SHORT_cCel
	Measurement returned by temperature_cCel() for an open thermistor. More...

Additional Inherited Members
Public Types inherited from nrfcxx::periph::ADCClient
using	flags_type = unsigned int
	Type for client-specific flags.

using	queued_callback_type = std::function< void(int rc)>
	Signature for application notification of completed queue operation. More...

using	peripheral = ADC::peripheral

using	mutex_type = peripheral::mutex_type
	Mutex required to inhibit ADC interrupts.

Protected Types inherited from nrfcxx::periph::ADCClient
enum	flags_e : flags_type { FL_QUEUED_SAMPLE = 0x0001, FL_QUEUED_CALIBRATE = 0x0002, FL_QUEUED_Msk = FL_QUEUED_SAMPLE \| FL_QUEUED_CALIBRATE, FL_SUBCLASS_BASE = 0x0010 }
	Defined values for flags. More...

Protected Member Functions inherited from nrfcxx::periph::ADCClient
int	sample_bi_ (const notifier_type &notify)
	Implements sample() given that the mutex is already held.

void	complete_queue_bi_ ()

virtual void	complete_bi_ ()
	Method invoked when the collection completes. More...

Static Protected Member Functions inherited from nrfcxx::periph::ADCClient
static void	process_queue_bi_ ()

Protected Attributes inherited from nrfcxx::periph::ADCClient
flags_type	flags_ = 0
	Flags for use by the core infrastructure and client specifications. More...

Detailed Description

Class supporting thermistor measurements.

Each thermistor is expected to be positioned as the upper resistor in a voltage divider. The value of the lower resistor and the Steinhart-Hart thermistor coefficients must be the same for all channels sampled by a given instance.

Constructor & Destructor Documentation

◆ ntcThermistor()

template<typename Iterator >

nrfcxx::sensor::adc::ntcThermistor::ntcThermistor	(	Iterator	ains_begin,
		Iterator	ains_end,
		volatile uint16_t *	raw = `nullptr`,
		const SteinhartHart *	coeff = `&steinhartHart::adafruit372fullScale`,
		unsigned int	ref_Ohm = `10000`
	)

inline

Generic constructor for an iterable set of thermistor channels and optional external storage.

Parameters

ains_begin	as with voltage_divider::voltage_divider.
ains_end	as with voltage_divider::voltage_divider.
raw	as with voltage_divider::voltage_divider.
coeff	pointer to the thermistor coefficients.
ref_Ohm	the value of the reference resistor in the thermistor voltage divider.

Member Function Documentation

◆ convert_adc16_cCel()

int nrfcxx::sensor::adc::ntcThermistor::convert_adc16_cCel ( unsigned int therm_adc16 )

Convert a measured voltage to a temperature.

Parameters

therm_adc16 the measured voltage in 16-bit ADC counts. A value of 65535 would correspond to Vcc (a shorted thermistor); a value of zero would correspond to no voltage (an open thermistor).

Returns: The measured temperature of the thermistor in hundredths of a degree Celsius, or OPEN_cCel or SHORT_cCel for a broken thermistor.

◆ temperature_cCel()

int nrfcxx::sensor::adc::ntcThermistor::temperature_cCel ( size_t ci = 0 )

Convert the stored measured voltage to a thermisor.

Parameters

ci	the thermistor channel to use.

Returns: as with convert_adc16_cCel()

Field Documentation

◆ INVALID_cCel

constexpr int nrfcxx::sensor::adc::ntcThermistor::INVALID_cCel = 30000

staticconstexpr

An flag value for invalid temperatures.

The value is chosen to allow its positive and negative values to be stored in an int16_t with magnitudes that are not reasonable for true observed measurements. Any observation with a magnitude equal to or greater than this is invalid.

Distinct values may indicate different types of failure. For example the base value indicates a reading that was not performed, while increasing the magnitude by one identifies thermistor inputs that are faulted short or open.

◆ OPEN_cCel

constexpr int nrfcxx::sensor::adc::ntcThermistor::OPEN_cCel = - SHORT_cCel

staticconstexpr

Measurement returned by temperature_cCel() for an open thermistor.

An open thermistor is diagnosed when the measured voltage across the thermistor is at or below #open_adc16. This is in the direction of extremely low temperatures.

Note: The magnitude of this value is greater than INVALID_cCel and is equal to the magnitude of SHORT_cCel. The value is negative.

◆ SHORT_cCel

constexpr int nrfcxx::sensor::adc::ntcThermistor::SHORT_cCel = INVALID_cCel + 1

staticconstexpr

Measurement returned by temperature_cCel() for a shorted thermistor.

A shorted thermistor is diagnosed when the measured voltage across the thermistor is at or above #short_adc16. This is in the direction of extremely high temperatures.

Note: The magnitude of this value is greater than INVALID_cCel and is equal to the magnitude of OPEN_cCel. The value is positive.

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

nrfcxx/sensor/adc.hpp

Public Member Functions

Data Fields

Static Public Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ntcThermistor()

Member Function Documentation

◆ convert_adc16_cCel()

◆ temperature_cCel()

Field Documentation

◆ INVALID_cCel

◆ OPEN_cCel

◆ SHORT_cCel