microbit-dal/source/MicroBitThermometer.cpp

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#include "MicroBit.h"
#include "nrf_soc.h"
/**
* Constructor.
* Create new object that can sense temperature.
* @param id the ID of the new MicroBitThermometer object.
*
* Example:
* @code
* thermometer(MICROBIT_ID_THERMOMETER);
* @endcode
*
* Possible Events:
* @code
* MICROBIT_THERMOMETER_EVT_CHANGED
* @endcode
*/
MicroBitThermometer::MicroBitThermometer(uint16_t id)
{
this->id = id;
this->samplePeriod = MICROBIT_THERMOMETER_PERIOD;
this->sampleTime = 0;
uBit.addIdleComponent(this);
}
/**
* Gets the current temperature of the microbit.
* @return the current temperature, in degrees celsius.
*
* Example:
* @code
* uBit.thermometer.getTemperature();
* @endcode
*/
int MicroBitThermometer::getTemperature()
{
if (isSampleNeeded())
updateTemperature();
return temperature;
}
/**
* Indicates if we'd like some processor time to sense the temperature. 0 means we're not due to read the tmeperature yet.
* @returns 1 if we'd like some processor time, 0 otherwise.
*/
int MicroBitThermometer::isIdleCallbackNeeded()
{
return isSampleNeeded();
}
/**
* periodic callback.
* Check once every second or so for a new temperature reading.
*/
void MicroBitThermometer::idleTick()
{
if (isSampleNeeded())
updateTemperature();
}
/**
* Determines if we're due to take another temeoratur reading
* @return 1 if we're due to take a temperature reading, 0 otherwise.
*/
int MicroBitThermometer::isSampleNeeded()
{
return ticks >= sampleTime;
}
/**
* Set the sample rate at which the temperatureis read (in ms).
* n.b. the temperature is alwasy read in the background, so wis only updated
* when the processor is idle, or when the temperature is explicitly read.
* The default sample period is 1 second.
* @param period the requested time between samples, in milliseconds.
*/
void MicroBitThermometer::setPeriod(int period)
{
samplePeriod = period;
}
/**
* Reads the currently configured sample rate of the thermometer.
* @return The time between samples, in milliseconds.
*/
int MicroBitThermometer::getPeriod()
{
return samplePeriod;
}
/**
* Updates our recorded temperature from the many sensors on the micro:bit!
*/
void MicroBitThermometer::updateTemperature()
{
int32_t processorTemperature;
// For now, we just rely on the nrf senesor to be the most accurate.
// The compass module also has a temperature sensor, and has the lowest power consumption, so will run the cooler...
// ...however it isn't trimmed for accuracy during manufacture, so requires calibration.
if (uBit.ble)
{
// If Bluetooth is enabled, we need to go through the Nordic software to safely do this
sd_temp_get(&processorTemperature);
}
else
{
// Othwerwise, we access the information directly...
uint32_t *TEMP = (uint32_t *)0x4000C508;
NRF_TEMP->TASKS_START = 1;
while (NRF_TEMP->EVENTS_DATARDY == 0);
NRF_TEMP->EVENTS_DATARDY = 0;
processorTemperature = *TEMP;
NRF_TEMP->TASKS_STOP = 1;
}
// Record our reading...
temperature = processorTemperature / 4;
// Schedule our next sample.
sampleTime = ticks + samplePeriod;
// Send an event to indicate that we'e updated our temperature.
MicroBitEvent e(id, MICROBIT_THERMOMETER_EVT_UPDATE);
}