CAC Interface

Detailed Description

Interface for clock frequency accuracy measurements.

Summary

The interface for the clock frequency accuracy measurement circuit (CAC) peripheral is used to check a system clock frequency with a reference clock signal by counting the number of pulses of the clock to be measured.

Data Structures
struct	cac_ref_clock_config_t
struct	cac_meas_clock_config_t
struct	cac_callback_args_t
struct	cac_cfg_t
struct	cac_api_t
struct	cac_instance_t

Typedefs
typedef void	cac_ctrl_t

Enumerations
enum	cac_event_t
enum	cac_clock_type_t
enum	cac_clock_source_t
enum	cac_ref_divider_t
enum	cac_ref_digfilter_t
enum	cac_ref_edge_t
enum	cac_meas_divider_t

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Data Structure Documentation

cac_ref_clock_config_t

struct cac_ref_clock_config_t

Structure defining the settings that apply to reference clock configuration.

Data Fields
cac_ref_divider_t	divider	Divider specification for the Reference clock.
cac_clock_source_t	clock	Clock source for the Reference clock.
cac_ref_digfilter_t	digfilter	Digital filter selection for the CACREF ext clock.
cac_ref_edge_t	edge	Edge detection for the Reference clock.

cac_meas_clock_config_t

struct cac_meas_clock_config_t

Structure defining the settings that apply to measurement clock configuration.

Data Fields
cac_meas_divider_t	divider	Divider specification for the Measurement clock.
cac_clock_source_t	clock	Clock source for the Measurement clock.

cac_callback_args_t

struct cac_callback_args_t

Callback function parameter data

Data Fields
cac_event_t	event	The event can be used to identify what caused the callback.
void *	p_context	Value provided in configuration structure.

cac_cfg_t

struct cac_cfg_t

CAC Configuration

Data Fields
cac_ref_clock_config_t	cac_ref_clock
	Reference clock specific settings.
cac_meas_clock_config_t	cac_meas_clock
	Measurement clock specific settings.
uint16_t	cac_upper_limit
	The upper limit counter threshold.
uint16_t	cac_lower_limit
	The lower limit counter threshold.
IRQn_Type	mendi_irq
	Measurement End IRQ number.
IRQn_Type	ovfi_irq
	Measurement Overflow IRQ number.
IRQn_Type	ferri_irq
	Frequency Error IRQ number.
uint8_t	mendi_ipl
	Measurement end interrupt priority.
uint8_t	ovfi_ipl
	Overflow interrupt priority.
uint8_t	ferri_ipl
	Frequency error interrupt priority.
void(*	p_callback )(cac_callback_args_t *p_args)
	Callback provided when a CAC interrupt ISR occurs.
void *	p_context
	Passed to user callback in cac_callback_args_t.
void const *	p_extend
	CAC hardware dependent configuration */.

cac_api_t

struct cac_api_t

CAC functions implemented at the HAL layer API

Data Fields
fsp_err_t(*	open )(cac_ctrl_t *const p_ctrl, cac_cfg_t const *const p_cfg)
fsp_err_t(*	startMeasurement )(cac_ctrl_t *const p_ctrl)
fsp_err_t(*	stopMeasurement )(cac_ctrl_t *const p_ctrl)
fsp_err_t(*	read )(cac_ctrl_t *const p_ctrl, uint32_t *const p_counter)
fsp_err_t(*	callbackSet )(cac_ctrl_t *const p_ctrl, void(*p_callback)(cac_callback_args_t *), void *const p_context, cac_callback_args_t *const p_callback_memory)
fsp_err_t(*	close )(cac_ctrl_t *const p_ctrl)

Field Documentation

open

fsp_err_t(* cac_api_t::open) (cac_ctrl_t *const p_ctrl, cac_cfg_t const *const p_cfg)

Open function for CAC device.

Parameters

[out]	p_ctrl	Pointer to CAC device control. Must be declared by user.
[in]	cac_cfg_t	Pointer to CAC configuration structure.

startMeasurement

fsp_err_t(* cac_api_t::startMeasurement) (cac_ctrl_t *const p_ctrl)

Begin a measurement for the CAC peripheral.

Parameters

[in]

p_ctrl

Pointer to CAC device control.

stopMeasurement

fsp_err_t(* cac_api_t::stopMeasurement) (cac_ctrl_t *const p_ctrl)

End a measurement for the CAC peripheral.

Parameters

[in]

p_ctrl

Pointer to CAC device control.

read

fsp_err_t(* cac_api_t::read) (cac_ctrl_t *const p_ctrl, uint32_t *const p_counter)

Read function for CAC peripheral.

Parameters

[in]	p_ctrl	Control for the CAC device context.
[in]	p_counter	Pointer to variable in which to store the current CACNTBR register contents.

callbackSet

fsp_err_t(* cac_api_t::callbackSet) (cac_ctrl_t *const p_ctrl, void(*p_callback)(cac_callback_args_t *), void *const p_context, cac_callback_args_t *const p_callback_memory)

Specify callback function and optional context pointer and working memory pointer.

Parameters

[in]	p_ctrl	Control block set in cac_api_t::open call
[in]	p_callback	Callback function to register
[in]	p_context	Pointer to send to callback function
[in]	p_working_memory	Pointer to volatile memory where callback structure can be allocated. Callback arguments allocated here are only valid during the callback.

close

fsp_err_t(* cac_api_t::close) (cac_ctrl_t *const p_ctrl)

Close function for CAC device.

Parameters

[in]

p_ctrl

Pointer to CAC device control.

cac_instance_t

struct cac_instance_t

This structure encompasses everything that is needed to use an instance of this interface.

Data Fields
cac_ctrl_t *	p_ctrl	Pointer to the control structure for this instance.
cac_cfg_t const *	p_cfg	Pointer to the configuration structure for this instance.
cac_api_t const *	p_api	Pointer to the API structure for this instance.

Typedef Documentation

cac_ctrl_t

typedef void cac_ctrl_t

CAC control block. Allocate an instance specific control block to pass into the CAC API calls.

Enumeration Type Documentation

cac_event_t

enum cac_event_t

Event types returned by the ISR callback when used in CAC interrupt mode

Enumerator
CAC_EVENT_FREQUENCY_ERROR	Frequency error.
CAC_EVENT_MEASUREMENT_COMPLETE	Measurement complete.
CAC_EVENT_COUNTER_OVERFLOW	Counter overflow.

cac_clock_type_t

enum cac_clock_type_t

Enumeration of the two possible clocks.

Enumerator
CAC_CLOCK_MEASURED	Measurement clock.
CAC_CLOCK_REFERENCE	Reference clock.

cac_clock_source_t

enum cac_clock_source_t

Enumeration of the possible clock sources for both the reference and measurement clocks.

Enumerator
CAC_CLOCK_SOURCE_MAIN_OSC	Main clock oscillator.
CAC_CLOCK_SOURCE_SUBCLOCK	Sub-clock.
CAC_CLOCK_SOURCE_HOCO	HOCO (High speed on chip oscillator)
CAC_CLOCK_SOURCE_MOCO	MOCO (Middle speed on chip oscillator)
CAC_CLOCK_SOURCE_LOCO	LOCO (Low speed on chip oscillator)
CAC_CLOCK_SOURCE_PCLKB	PCLKB (Peripheral Clock B)
CAC_CLOCK_SOURCE_IWDT	IWDT-dedicated on-chip oscillator.
CAC_CLOCK_SOURCE_EXTERNAL	Externally supplied measurement clock on CACREF pin.

cac_ref_divider_t

enum cac_ref_divider_t

Enumeration of available dividers for the reference clock.

Enumerator
CAC_REF_DIV_32	Reference clock divided by 32.
CAC_REF_DIV_128	Reference clock divided by 128.
CAC_REF_DIV_1024	Reference clock divided by 1024.
CAC_REF_DIV_8192	Reference clock divided by 8192.

cac_ref_digfilter_t

enum cac_ref_digfilter_t

Enumeration of available digital filter settings for an external reference clock.

Enumerator
CAC_REF_DIGITAL_FILTER_OFF	No digital filter on the CACREF pin for reference clock.
CAC_REF_DIGITAL_FILTER_1	Sampling clock for digital filter = measuring frequency.
CAC_REF_DIGITAL_FILTER_4	Sampling clock for digital filter = measuring frequency/4.
CAC_REF_DIGITAL_FILTER_16	Sampling clock for digital filter = measuring frequency/16.

cac_ref_edge_t

enum cac_ref_edge_t

Enumeration of available edge detect settings for the reference clock.

Enumerator
CAC_REF_EDGE_RISE	Rising edge detect for the Reference clock.
CAC_REF_EDGE_FALL	Falling edge detect for the Reference clock.
CAC_REF_EDGE_BOTH	Both Rising and Falling edges detect for the Reference clock.

cac_meas_divider_t

enum cac_meas_divider_t

Enumeration of available dividers for the measurement clock

Enumerator
CAC_MEAS_DIV_1	Measurement clock divided by 1.
CAC_MEAS_DIV_4	Measurement clock divided by 4.
CAC_MEAS_DIV_8	Measurement clock divided by 8.
CAC_MEAS_DIV_32	Measurement clock divided by 32.