Delay Functions

PiOS Delay functionality. More...

Data Structures
struct	rtc_callback_entry

Macros
#define	SYSTICK_HZ   1250
#define	RTC_DIVIDER   2 /* Must be power of 2; this results in 625Hz "RTC" */
#define	PIOS_RTC_MAX_CALLBACKS   3

Functions
int32_t	PIOS_DELAY_Init (void)
int32_t	PIOS_DELAY_WaituS (uint32_t uS)
int32_t	PIOS_DELAY_WaitmS (uint32_t mS)
uint32_t	PIOS_DELAY_GetuS ()
	Query the Delay timer for the current uS. More...
uint32_t	PIOS_DELAY_GetuSSince (uint32_t t)
	Calculate time in microseconds since a previous time. More...
uint32_t	PIOS_DELAY_GetuSExpired (uint32_t t)
	Calculates whether a given time has passed. More...
uint32_t	PIOS_DELAY_GetRaw ()
	Get the raw delay timer, useful for timing. More...
uint32_t	PIOS_DELAY_DiffuS (uint32_t raw)
	Subtract raw time from now and convert to us. More...
uint32_t	PIOS_DELAY_DiffuS2 (uint32_t raw, uint32_t later)
	Subrtact two raw times and convert to us. More...
static uint32_t	get_monotonic_us_time (void)
static void	PIOS_DELAY_Systick_Handler (void)
float	PIOS_RTC_Rate ()
float	PIOS_RTC_MsPerTick ()
bool	PIOS_RTC_RegisterTickCallback (void(*fn)(uintptr_t id), uintptr_t data)
static void	PIOS_RTC_Tick ()

Variables
static uint32_t	base_time
static uint32_t	us_ticks
static uint32_t	us_modulo
static struct rtc_callback_entry	rtc_callback_list [PIOS_RTC_MAX_CALLBACKS]

Detailed Description

PiOS Delay functionality.

Macro Definition Documentation

#define PIOS_RTC_MAX_CALLBACKS   3

Definition at line 39 of file pios_delay.c.

#define RTC_DIVIDER   2 /* Must be power of 2; this results in 625Hz "RTC" */

Definition at line 37 of file pios_delay.c.

#define SYSTICK_HZ   1250

Definition at line 36 of file pios_delay.c.

Function Documentation

static uint32_t get_monotonic_us_time ( void  )

static

Definition at line 73 of file pios_delay.c.

uint32_t PIOS_DELAY_DiffuS

(

uint32_t

raw

)

Subtract raw time from now and convert to us.

Returns

A microsecond value

Definition at line 159 of file pios_delay.c.

uint32_t PIOS_DELAY_DiffuS2	(	uint32_t	raw,
		uint32_t	later
	)

Subrtact two raw times and convert to us.

Returns

Interval between raw times in microseconds

Definition at line 164 of file pios_delay.c.

uint32_t PIOS_DELAY_GetRaw

(

)

Get the raw delay timer, useful for timing.

Returns

Unitless value (uint32 wrap around)

Definition at line 153 of file pios_delay.c.

uint32_t PIOS_DELAY_GetuS

(

)

Query the Delay timer for the current uS.

Returns

A microsecond value

Todo:

fixup to be more precise

Definition at line 173 of file pios_delay.c.

uint32_t PIOS_DELAY_GetuSExpired

(

uint32_t

t

)

Calculates whether a given time has passed.

Parameters

[in]

t

the time in question

Returns

true if the time is in the past.

Definition at line 193 of file pios_delay.c.

uint32_t PIOS_DELAY_GetuSSince

(

uint32_t

t

)

Calculate time in microseconds since a previous time.

Parameters

[in]

t

previous time

Returns

time in us since previous time t.

Definition at line 183 of file pios_delay.c.

int32_t PIOS_DELAY_Init

(

void

)

Initialises the Timer used by PIOS_DELAY functions
This is called from pios.c as part of the main() function at system start up.

Returns

< 0 if initialisation failed

Initialises the Timer used by PIOS_DELAY functions.

Returns

always zero (success)

Definition at line 98 of file pios_delay.c.

static void PIOS_DELAY_Systick_Handler ( void  )

static

Definition at line 48 of file pios_delay.c.

int32_t PIOS_DELAY_WaitmS

(

uint32_t

ms

)

Waits for a specific number of mS
Example:

// Wait for 500 mS
PIOS_DELAY_Wait_mS(500);

Parameters

[in]

mS

delay (1..65535 milliseconds)

Returns

< 0 on errors

Waits for a specific number of mS

Example:

// Wait for 500 mS
PIOS_DELAY_Wait_mS(500);

Parameters

[in]

mS

delay (1..65535 milliseconds)

Returns

< 0 on errors

Definition at line 140 of file pios_delay.c.

int32_t PIOS_DELAY_WaituS

(

uint32_t

us

)

Waits for a specific number of uS
Example:

// Wait for 500 uS
PIOS_DELAY_Wait_uS(500);

Parameters

[in]

uS

delay (1..65535 microseconds)

Returns

< 0 on errors

Waits for a specific number of uS

Example:

// Wait for 500 uS
PIOS_DELAY_Wait_uS(500);

Parameters

[in]

uS

delay

Returns

< 0 on errors

Definition at line 116 of file pios_delay.c.

float PIOS_RTC_MsPerTick

(

)

Definition at line 180 of file pios_delay.c.

float PIOS_RTC_Rate

(

)

Definition at line 175 of file pios_delay.c.

bool PIOS_RTC_RegisterTickCallback	(	void(*)(uintptr_t id)	fn,
		uintptr_t	data
	)

Definition at line 185 of file pios_delay.c.

static void PIOS_RTC_Tick ( )

static

Definition at line 203 of file pios_delay.c.

Variable Documentation

uint32_t base_time

static

This is the value used as a base. Strictly not required, as times can be expected to wrap... But it makes sense to get sane numbers at first that will agree with the PIOS_Thread ones etc.

Definition at line 42 of file pios_delay.c.

struct rtc_callback_entry rtc_callback_list[PIOS_RTC_MAX_CALLBACKS]

static

Definition at line 46 of file pios_delay.c.

uint32_t us_modulo

static

Definition at line 39 of file pios_delay.c.

uint32_t us_ticks

static

Definition at line 38 of file pios_delay.c.