SRF08 ultrasonic range sensor

Driver for the SRF08 ultrasonic range sensor. More...

Detailed Description

Driver for the SRF08 ultrasonic range sensor.

The connection between the MCU and the SRF08 is based on the i2c-interface.

Files
file	srf08.h
	Driver definitions for the SRF02 ultrasonic ranger.
file	srf08_params.h
	Default configuration for srf08 devices.

Data Structures
struct	srf08_params_t
	Device initialization parameters. More...
struct	srf08_t
	Device descriptor for SRF08 sensors. More...

Macros
#define	SRF08_COMMAND_REG   0x0
	The sensors command register (write)
#define	SRF08_GAIN_REG   0x1
	Max. More...
#define	SRF08_RANGE_REG   0x2
	The sensors range register (write)
#define	SRF08_RANGE_HIGH_BYTE   0x2
	The upper measurement byte (read)
#define	SRF08_RANGE_LOW_BYTE   0x3
	The lower measurement byte (read)
#define	SRF08_MAX_REGISTER_NUMBER   35
	Number of highest register.
#define	SRF08_MAX_ECHO_NUMBER   17
	Maximum number of echos from more distant objects.
#define	SRF08_MAX_RANGE_6M   0x8C
	Maximum range the sensor can measure (6m)
#define	SRF08_MAX_GAIN   0x1F
	Maximum gain of the sensor (1025)

Enumerations
enum	srf08_mode_t {   SRF08_MODE_INCH = 0x50, SRF08_MODE_CM = 0x51, SRF08_MODE_MICRO_SEC = 0x52, SRF08_ANN_MODE_INCH = 0x53,   SRF08_ANN_MODE_CM = 0x54, SRF08_ANN_MODE_MICRO_SEC = 0x55 }
	Possible measurement modes for the SRF08 sensor. More...

Functions
int	srf08_init (srf08_t *dev, const srf08_params_t *params)
	Initialize the SRF08 ultrasonic sensor. More...
int	srf08_set_max_range (const srf08_t *dev, uint8_t max_range)
	Set the maximum range of the SRF08. More...
int	srf08_set_max_gain (const srf08_t *dev, uint8_t max_gain)
	Set the maximum of the analog stages. More...
int	srf08_get_distances (const srf08_t *dev, uint16_t *range_array, int num_echos, srf08_mode_t ranging_mode)
	Get all distances measured from the SRF08 ultrasonic sensor. More...

Macro Definition Documentation

SRF08_GAIN_REG

#define SRF08_GAIN_REG   0x1

Max.

gain register (write)

Definition at line 42 of file srf08.h.

Enumeration Type Documentation

srf08_mode_t

enum srf08_mode_t

Possible measurement modes for the SRF08 sensor.

Enumerator
SRF08_MODE_INCH	result in inches
SRF08_MODE_CM	result in centimeters
SRF08_MODE_MICRO_SEC	result in centimeters
SRF08_ANN_MODE_INCH	synchronous measurement in inch
SRF08_ANN_MODE_CM	synchronous measurement in cm
SRF08_ANN_MODE_MICRO_SEC	synchronous measurement in us

Definition at line 83 of file srf08.h.

Function Documentation

srf08_get_distances()

int srf08_get_distances	(	const srf08_t *	dev,
		uint16_t *	range_array,
		int	num_echos,
		srf08_mode_t	ranging_mode
	)

Get all distances measured from the SRF08 ultrasonic sensor.

The results of a ranging can be returned in inches, centimeters or microseconds. The SRF08 can detect up to 17 targets.

Parameters

[in]	dev	device descriptor of an SRF08 sensor
[in]	range_array	a pointer to a buffer holding the ranging results.
[in]	num_echos	number of stored measurements (echos)
[in]	ranging_mode	there are three real ranging modes, which return the result in inches, centimeters or microseconds. Another set of three fake ranging modes do the same but without transmitting the burst.

Returns

number of measured echos on success

-1 on ranging mode errors

-2 if num_echos exceeds the max. number of possible measurements

-3 if i2c read high byte failed

-4 if i2c read low byte failed

srf08_init()

int srf08_init	(	srf08_t *	dev,
		const srf08_params_t *	params
	)

Initialize the SRF08 ultrasonic sensor.

Parameters

[in]	dev	device descriptor of an SRF08 sensor
[in]	params	initialization parameters

Returns

0 on successful initialization

-3 on max. range error

-4 on max. gain error

srf08_set_max_gain()

int srf08_set_max_gain	(	const srf08_t *	dev,
		uint8_t	max_gain
	)

Set the maximum of the analog stages.

@ note This value is just a limitation of the maximum amplification and not the actual. While measuring, this value starts at its minimum and increases approx. each 75 us until the maximum value is reached.

Parameters

[in]	dev	device descriptor of an SRF08 sensor
[in]	max_gain	the maximal gain value.

Returns

1 on success

-1 on undefined device given

srf08_set_max_range()

int srf08_set_max_range	(	const srf08_t *	dev,
		uint8_t	max_range
	)

Set the maximum range of the SRF08.

Parameters

[in]	dev	device descriptor of an SRF08 sensor
[in]	max_range	the adjusted maximal range is: max_range = (max_range x 43mm) + 43mm. The hardware limit is 6m.

Returns

1 on success

-1 on undefined device given