ABP2 series Honeywell pressure and temperature sensor driver

SPI and I2C pressure and temperature sensor driver. More...

Detailed Description

SPI and I2C pressure and temperature sensor driver.

Description

The unit and the range depend on the part number of the sensor. The default parameters assume a 0..160 mbar model. It is the responsibility of the user to use homogeneous units, depending on the actual sensor being used. The pressure range is set when calling abp2_init().

This driver provides [S]ensor [A]ctuator [U]ber [L]ayer capabilities. The functions return 0 on success or a negative value made from errno.h on error.

Usage

See RIOT/tests/drivers/abp2 for an example application using this driver.

Add the following modules to the application makefile:

USEMODULE += abp2
USEMODULE += abp2_spi

When the I2C version is supported, abp2_i2c can be used for I2C sensors instead of abp2_spi.

To use the SAUL interface, add also to the makefile:

USEMODULE += saul_default

Initialize the driver by calling abp2_init().

When a measurement is started on the sensor, its internal ADC converts both pressure and temperature. The conversion takes about 5ms. These two values are retrieved in a single bus transfer.

There are three ways to use the driver:

• blocking mode : call abp2_read()
• non-blocking mode : call abp2_read_nb()
• the SAUL interface

The first one will block for about 5ms and return the latest data, while the second one will return almost immediately but will return data from the previous ADC conversion.

Caveats

This driver currently doesn't support the I2C flavor of these sensors.

Topics
	Status bits
	Macro definitions to manipulate the bits of the status byte.

Files
file	abp2_params.h
	Default configuration for ABP2 capaticance-to-digital converter.
file	abp2.h
	Honeywell ABP2 series pressure and temperature sensor driver.

Data Structures
struct	abp2_params
	Parameters for ABP2 sensors. More...
struct	abp2
	Device descriptor for ABP2 sensors. More...
struct	abp2_raw
	Raw values read from a ABP2 sensor. More...

Typedefs
typedef struct abp2_params	abp2_params_t
	Parameters for ABP2 sensors.
typedef struct abp2	abp2_t
	Device descriptor for ABP2 sensors.
typedef struct abp2_raw	abp2_raw_t
	Raw values read from a ABP2 sensor.

Functions
int	abp2_init (abp2_t *dev, const abp2_params_t *params)
	Initialize the ABP2 sensor.
int	abp2_measure (const abp2_t *dev)
	Let the sensor make one measurement.
int	abp2_read (const abp2_t *dev, int32_t *press, int32_t *temp)
	Measure pressure and temperature (blocking version).
int	abp2_read_nb (const abp2_t *dev, int32_t *press, int32_t *temp)
	Measure pressure and temperature (non-blocking version).
uint8_t	abp2_getstatus (const abp2_t *dev)
	Read the status byte of the sensor.
int	abp2_read_raw (const abp2_t *dev, abp2_raw_t *raw_values)
	Read pressure and temperature raw values.
int	abp2_measure_read (const abp2_t *dev, abp2_raw_t *raw_values)
	Start measurement and read previous pressure and temperature raw values.
int32_t	abp2_pressure (const abp2_t *dev, const abp2_raw_t *raw_values)
	Convert ADC counts to pressure.
int32_t	abp2_temperature (const abp2_t *dev, const abp2_raw_t *raw_values)
	Convert ADC counts to temperature .

Typedef Documentation

abp2_params_t

typedef struct abp2_params abp2_params_t

Parameters for ABP2 sensors.

The range must be set in thousandths of sensor unit. For example, if the sensor unit is mbar, set the rangeMin and rangeMax properties in µbar.

Function Documentation

abp2_getstatus()

uint8_t abp2_getstatus

(

const abp2_t *

dev

)

Read the status byte of the sensor.

Parameters

[in]

dev

Sensor device descriptor.

See also

Status bits

Returns

The status byte.

abp2_init()

int abp2_init	(	abp2_t *	dev,
		const abp2_params_t *	params )

Initialize the ABP2 sensor.

Parameters

[in]	dev	Sensor device descriptor.
[in]	params	Sensor parameters.

See also

abp2_params.

Assign the parameters params to the device descriptor dev. Poll the device until the busy flag clears or the operation times out. On SPI version, init the chip select pin.

Note

The bus is expected to be initialized when calling this function.

params sets the sensor range.

Returns

0 on success

-EIO on bus error or -ETIMEDOUT on timeout.

abp2_measure()

int abp2_measure

(

const abp2_t *

dev

)

Let the sensor make one measurement.

Parameters

[in]

dev

Sensor device descriptor.

This function lets the sensor transition from standby to operation mode and make one measurement, after which it will automatically return to standby mode. Call abp2_read_raw() to retrieve the data.

Returns

0 on success

-ENODATA on sensor error.

abp2_measure_read()

int abp2_measure_read	(	const abp2_t *	dev,
		abp2_raw_t *	raw_values )

Start measurement and read previous pressure and temperature raw values.

Parameters

[in]	dev	Sensor device descriptor.
[out]	raw_values	Raw values read from the sensor.

Read the raw values, i.e. ADC counts that result from the previous measurement. Then, populate raw_values. The raw values can be converted to physical quantities with abp2_pressure() and abp2_temperature().

Precondition

A measurement must have been initiated by abp2_measure() or a previous call to this function, in order to retrieve valid data.

Note

This function leads to concise user code. However, in order to get valid data, it must be called periodically, and at short intervals. If the application favors power savings i.e. low frequency measurements, then abp2_measure() and abp2_read_raw() are a better option.

Returns

0 on success

-ENODATA on sensor error.

abp2_pressure()

int32_t abp2_pressure	(	const abp2_t *	dev,
		const abp2_raw_t *	raw_values )

Convert ADC counts to pressure.

Parameters

[in]	dev	Sensor device descriptor.
[in]	raw_values	Raw values read from the sensor.

See also

abp2_params to know how to set the sensor range.

Returns

The pressure in thousandths of user units, as set in the parameters of abp2_init().

abp2_read()

int abp2_read	(	const abp2_t *	dev,
		int32_t *	press,
		int32_t *	temp )

Measure pressure and temperature (blocking version).

Parameters

[in]	dev	Sensor device descriptor.
[out]	press	Pressure value read from the sensor (thousandths of sensor unit).
[out]	temp	Temperature read from the sensor (milli-degrees Celsius).

This function is blocking. It starts a conversion on the sensor ADC for both pressure and temperature, waits until the busy flag clears or for a 10ms timeout, reads the values from the sensor and converts them to physical quantities.

See also

The non-blocking version: abp2_read_nb().

Returns

0 on success

-ETIMEDOUT on timeout

-ENODATA on sensor error

abp2_read_nb()

int abp2_read_nb	(	const abp2_t *	dev,
		int32_t *	press,
		int32_t *	temp )

Measure pressure and temperature (non-blocking version).

Parameters

[in]	dev	Sensor device descriptor.
[out]	press	Pressure value read from the sensor (thousandths of sensor unit).
[out]	temp	Temperature read from the sensor (milli-degrees Celsius).

This function starts a conversion on the sensor ADC and reads the values from the previous conversion in a single bus transfer and converts them to physical quantities.

See also

The blocking version: abp2_read().

Returns

0 on success

-ENODATA on sensor error

abp2_read_raw()

int abp2_read_raw	(	const abp2_t *	dev,
		abp2_raw_t *	raw_values )

Read pressure and temperature raw values.

Parameters

[in]	dev	Sensor device descriptor.
[out]	raw_values	Raw values read from the sensor.

Read the raw values, i.e. ADC counts and populate raw_values. The raw values can be converted to physical quantities with abp2_pressure() and abp2_temperature().

Precondition

A measurement must have been initiated by abp2_measure() and have completed (ca. 5ms).

Returns

0 on success

-ENODATA on sensor error.

abp2_temperature()

int32_t abp2_temperature	(	const abp2_t *	dev,
		const abp2_raw_t *	raw_values )

Convert ADC counts to temperature .

Parameters

[in]	dev	Sensor device descriptor.
[in]	raw_values	Raw values read from the sensor.

Returns

The temperature in milli-degrees Celsius.