NTC Thermistor

General Description

APIs for interacting with an NTC thermistor e.g the NCP18XH103F03RB resistor on the CY8CPROTO-062-4343W board or the CY8CKIT-028-EPD shield Note: This lib uses floating point calculations during temperature calculation so it is recommended to enable floating point support.

Data Structures
struct	mtb_thermistor_ntc_gpio_cfg_t
	Configuration structure containing ntc thermistor constants. More...
struct	mtb_thermistor_ntc_gpio_t
	Structure defining the pins and adc channel used to interact with the ntc thermistor. More...

Enumerations
enum	mtb_thermistor_ntc_wiring {   MTB_THERMISTOR_NTC_WIRING_VIN_R_NTC_GND,   MTB_THERMISTOR_NTC_WIRING_VIN_NTC_R_GND }
	Defines the way the NTC thermistor is wired up: Vin-NTC-R-GND or Vin-R-NTC-GND. More...

Functions
cy_rslt_t	mtb_thermistor_ntc_gpio_init (mtb_thermistor_ntc_gpio_t *obj, cyhal_adc_t *adc, cyhal_gpio_t gnd, cyhal_gpio_t vdd, cyhal_gpio_t out, mtb_thermistor_ntc_gpio_cfg_t *cfg, mtb_thermistor_ntc_wiring wiring)
	Initialize the ADC Channel and Pins to communicate with the thermistor. More...
float	mtb_thermistor_ntc_gpio_get_temp (mtb_thermistor_ntc_gpio_t *obj)
	Gets the temperature reading, in degrees C, from the thermistor. More...
void	mtb_thermistor_ntc_gpio_free (mtb_thermistor_ntc_gpio_t *obj)
	Frees up the ADC channel and Pins allocated for the thermistor. More...

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Data Structure Documentation

mtb_thermistor_ntc_gpio_cfg_t

struct mtb_thermistor_ntc_gpio_cfg_t

Data Fields
float	r_ref	Resistance of the reference resistor.
float	b_const	Beta constant of the thermistor.
float	r_infinity	Projected resistance of the thermistor at infinity.

mtb_thermistor_ntc_gpio_t

struct mtb_thermistor_ntc_gpio_t

Data Fields
cyhal_adc_channel_t	channel	Adc channel obj.
cyhal_gpio_t	gnd	Ground reference pin.
cyhal_gpio_t	vdd	VDD reference pin.
cyhal_gpio_t	out	Voltage output.
mtb_thermistor_ntc_gpio_cfg_t *	cfg	Ptr to thermistor cfg structure.
mtb_thermistor_ntc_wiring	wiring	How the thermistor is wired up.

Enumeration Type Documentation

mtb_thermistor_ntc_wiring

enum mtb_thermistor_ntc_wiring

Defines the way the NTC thermistor is wired up: Vin-NTC-R-GND or Vin-R-NTC-GND.

Enumerator
MTB_THERMISTOR_NTC_WIRING_VIN_R_NTC_GND	The thermistor is connected to Ground with the resister between it and Vin.
MTB_THERMISTOR_NTC_WIRING_VIN_NTC_R_GND	The thermistor is connected to Vin with the resister between it and ground.

Function Documentation

mtb_thermistor_ntc_gpio_init()

cy_rslt_t mtb_thermistor_ntc_gpio_init	(	mtb_thermistor_ntc_gpio_t *	obj,
		cyhal_adc_t *	adc,
		cyhal_gpio_t	gnd,
		cyhal_gpio_t	vdd,
		cyhal_gpio_t	out,
		mtb_thermistor_ntc_gpio_cfg_t *	cfg,
		mtb_thermistor_ntc_wiring	wiring
	)

Initialize the ADC Channel and Pins to communicate with the thermistor.

Parameters

[in,out]	obj	Pointer to a thermistor object containing the set of pins and adc channel that are associated with the thermistor. Note: The caller must allocate the memory for this object but the init function will initialize its contents.
[out]	obj	Pointer to a Thermistor object. The caller must allocate the memory for this object but the init function will initialize its contents.
[in]	adc	Pointer to an already initialized adc object
[in]	gnd	Ground reference pin
[in]	vdd	VDD reference pin
[in]	out	Voltage output pin
[in]	cfg	Pointer to the cfg object containing the thermistor constants
[in]	wiring	How the circuit is wired up

Returns

CY_RSLT_SUCCESS if properly initialized, else an error indicating what went wrong.

mtb_thermistor_ntc_gpio_get_temp()

float mtb_thermistor_ntc_gpio_get_temp

(

mtb_thermistor_ntc_gpio_t *

obj

)

Gets the temperature reading, in degrees C, from the thermistor.

Parameters

[in]

obj

Pointer to a thermistor object containing the set of pins and adc channel that are associated with the thermistor.

Returns

The temperature reading, in degrees C, from the hardware.

mtb_thermistor_ntc_gpio_free()

void mtb_thermistor_ntc_gpio_free

(

mtb_thermistor_ntc_gpio_t *

obj

)

Frees up the ADC channel and Pins allocated for the thermistor.

Parameters

[in]

obj

The set of pins and adc channel that are associated with the thermistor