uBit.thermometer#

Overview#

MicroBitThermometer provides access to the surface temperature of the nrf51822. The temperature reading therefore is not representative of the ambient temperature, but rather the temperature relative to the surface temperature of the chip.

However, we can make it representative of the ambient temperature in software through “calibrating” the thermometer.

Calibration is very simple, and is calculated by giving the current temperature to the setCalibration() member function. From the temperature, an offset is calculated, and is subsequently used to offset future temperature readings.

Real time updates#

When using the standard uBit presentation, the thermometer is continuously updated in the background using an idle thread (after it is first used), which is executed whenever the micro:bit has no other tasks to perform.

If there is no scheduler running, the values are synchronously read on getTemperature() calls. Additionally, if you would like to drive thermometer updates manually updateSample() can be used.

Message Bus ID#

Constant Value
MICROBIT_ID_THERMOMETER 28

Message Bus Events#

Constant Value
MICROBIT_THERMOMETER_EVT_UPDATE 1

API#

Constructor#


MicroBitThermometer(
MicroBitStorage &
_storage)#

Description#

Constructor. Create new MicroBitThermometer that gives an indication of the current temperature.

Parameters#

MicroBitStorage &
_storage - an instance of MicroBitStorage used to persist temperature offset data

Example#
 MicroBitStorage storage; 
 MicroBitThermometer thermometer(storage);


MicroBitThermometer(
MicroBitStorage &
_storage,
uint16_t
id)#

Description#

Constructor. Create new MicroBitThermometer that gives an indication of the current temperature.

Parameters#

MicroBitStorage &
_storage - an instance of MicroBitStorage used to persist temperature offset data

uint16_t
id - the unique EventModel id of this component. Defaults to MICROBIT_ID_THERMOMETER.

Example#
 MicroBitStorage storage; 
 MicroBitThermometer thermometer(storage);


MicroBitThermometer()#

Description#

Constructor. Create new MicroBitThermometer that gives an indication of the current temperature.

Example#
 MicroBitThermometer thermometer;


MicroBitThermometer(
uint16_t
id)#

Description#

Constructor. Create new MicroBitThermometer that gives an indication of the current temperature.

Parameters#

uint16_t
id - the unique EventModel id of this component. Defaults to MICROBIT_ID_THERMOMETER.

Example#
 MicroBitThermometer thermometer;

setPeriod#


void
setPeriod
(
int
period)#

Description#

Set the sample rate at which the temperatureis read (in ms).

The default sample period is 1 second.

Parameters#

int
period - the requested time between samples, in milliseconds.

Note

the temperature is always read in the background, and is only updated when the processor is idle, or when the temperature is explicitly read.

getPeriod#


int
getPeriod
()#

Description#

Reads the currently configured sample rate of the thermometer.

Returns#

The time between samples, in milliseconds.

setOffset#


int
setOffset
(
int
offset)#

Description#

Set the value that is used to offset the raw silicon temperature.

Parameters#

int
offset - the offset for the silicon temperature

Returns#

MICROBIT_OK on success

getOffset#


int
getOffset
()#

Description#

Retreive the value that is used to offset the raw silicon temperature.

Returns#

the current offset.

setCalibration#


int
setCalibration
(
int
calibrationTemp)#

Description#

This member function fetches the raw silicon temperature, and calculates the value used to offset the raw silicon temperature based on a given temperature.

Parameters#

int
calibrationTemp - the temperature used to calculate the raw silicon temperature offset.

Returns#

MICROBIT_OK on success

getTemperature#


int
getTemperature
()#

Description#

Gets the current temperature of the microbit.

Returns#

the current temperature, in degrees celsius.

Example#
 thermometer.getTemperature();

updateSample#


int
updateSample
()#

Description#

Updates the temperature sample of this instance of MicroBitThermometer only if isSampleNeeded() indicates that an update is required.

This call also will add the thermometer to fiber components to receive periodic callbacks.

Returns#

MICROBIT_OK on success.