srf04 ultra sonic range finder

Device driver for the srf04 ultra sonic range finder. More...

Detailed Description

Device driver for the srf04 ultra sonic range finder.

Files
file	srf04.h
	Device driver for the srf04 ultra sonic range finder.
file	srf04_params.h
	Default configuration for srf04 devices.

Data Structures
struct	srf04_params_t
	GPIO pins for srf04 device. More...
struct	srf04_t
	Device descriptor for srf04 sensor. More...

Enumerations
enum	{ SRF04_OK = 0, SRF04_ERR_INVALID = -1, SRF04_ERR_MEASURING = -2, SRF04_ERR_GPIO = -3 }
	Status and error return codes. More...

Functions
int	srf04_init (srf04_t *dev, const srf04_params_t *params)
	Initialize gpio and interrupt. More...
void	srf04_trigger (const srf04_t *dev)
	Triggers measurement. More...
int	srf04_read (const srf04_t *dev)
	Returns time of flight in ms. More...
int	srf04_get_distance (const srf04_t *dev)
	Convenience function triggers a measurement and returns distance. More...

Enumeration Type Documentation

anonymous enum

anonymous enum

Status and error return codes.

Enumerator
SRF04_OK	exit without error
SRF04_ERR_INVALID	error no valid measurement available
SRF04_ERR_MEASURING	error sensor is measuring
SRF04_ERR_GPIO	error initializing gpio

Definition at line 37 of file srf04.h.

Function Documentation

srf04_get_distance()

int srf04_get_distance

(

const srf04_t *

dev

)

Convenience function triggers a measurement and returns distance.

Note

This function will return after 50 ms once new data is available

Parameters

[in]

dev

device descriptor of sensor

Returns

time of flight in mm

SRF04_MEASURING if measurement is in progress

SRF04_INVALID if no valid measurement is available

srf04_init()

int srf04_init	(	srf04_t *	dev,
		const srf04_params_t *	params
	)

Initialize gpio and interrupt.

Parameters

[out]	dev	device descriptor of sensor to initialize
[in]	params	init param struct holding gpio trigger and echo pins

Returns

SRF04_OK on success

SRF04_GPIO on gpio init failure

srf04_read()

int srf04_read

(

const srf04_t *

dev

)

Returns time of flight in ms.

Note

should not be invoked within 50 ms after triggering

Parameters

[in]

dev

device descriptor of sensor

Returns

time of flight in ms

SRF04_MEASURING if measurement is in progress

SRF04_INVALID if no valid measurement is available

srf04_trigger()

void srf04_trigger

(

const srf04_t *

dev

)

Triggers measurement.

Parameters

[in]

dev

device descriptor of sensor