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Driver update methods

  • Article

A sensor driver supports internal methods that handle updates to the current report interval, change sensitivity, and so on. The pseudocode demonstrates this using the following methods:

  • DriverUpdateCRI(sensorID)
  • DriverUpdateCS(sensorID)
  • DriverUpdateLDA(sensorID)
  • DriverUpdateSensorState(sensorID, state, events)
  • DriverUpdateDatafields(sensorID)

Sensor reporting-field updates

The DriverUpdateCRI, DriverUpdateCS, and DriverUpdateLDA methods demonstrate how a driver updates the current report interval, change sensitivity, and location data accuracy fields.

DriverUpdateCRI(sensorID)
{
    if (true == flagCRI)
    {
        // Note that only the clients that have specified a CRI are considered
        // when determining which client has the lowest requested CRI
        Set selectedCRI of sensorID device to lowest of clientCRIs

        if (selectedCRI < effectiveMinCRI)
        {
            selectedCRI = effectiveMinCRI
        }
    }
    else //no client has specified a CRI
    {
        selectedCRI = defaultCRI
    }

    effectiveCRI = DriverUpdateSensorDeviceCRI(sensorID, selectedCRI)
}

DriverUpdateCS(sensorID)
{
    for (each datafield supported by sensorID)
    {
        if (true == flagCS)
        {
            // Note that only the clients that have specified a CS are considered
            // when determining which client has the lowest requested CS
            Set selectedCS[n] of sensorID device to lowest of clientCS[n]
        }
        else //no client has specified a CS
        {
            selectedCS[n] = defaultCS[n]
        }
    }

    effectiveCS[] = DriverUpdateSensorDeviceCS(sensorID, selectedCS[])
}

DriverUpdateLDA(sensorID)
{
    if (true == flagLDA)
    {
        // Note that only the clients that have specified an LDAare considered
        // when determining which client has the lowest (most accurate) requested LDA
        Set selectedLDA of sensorID device to lowest (most accurate) of clientLDAs
    }
    else //no client has specified a LDA
    {
        selectedLDA = defaultLDA
    }

    effectiveLDA = DriverUpdateSensorDeviceLDA(sensorID, selectedLDA)
}

Sensor state updates

The DriverUpdateSensorState method demonstrates how a driver updates the sensor event reporting and power states.

DriverUpdateSensorState(sensorID)
{
    if (clientCount == 0) // no clients
    {
        if (subscriberCount == 0) //no subscribers
        {
            selectedRS = reportingStateNoEvents
            selectedPS = powerStatePowerOff
        }
        else //has subscribers
        {
            //illegal state
            selectedRS = reportingStateNoEvents
            selectedPS = powerStatePowerOff
        }
    }
    else //has clients
    {
        if (subscriberCount == 0) //no subscribers
        {
            if (true == flagCRI)
            {
                selectedRS = reportingStateAllEvents
                selectedPS = powerStateFullPower
            }
            else
            {
                selectedRS = reportingStateNoEvents
                selectedPS = powerStateLowPower
            }
            else

        }
        else //has subscribers
        {
            selectedRS = reportingStateAllEvents
            selectedPS = powerStateFullPower
        }
    }

    effectiveRS = DriverUpdateSensorDeviceRS(sensorID, selectedRS)
    effectivePS = DriverUpdateSensorDevicePS(sensorID, selectedPS)
}

Data field updates

The DriverUpdateDatafields method demonstrates how a driver updates its data fields.

DriverUpdateDatafields(sensorID)
{
    if (effectiveRS == eventsOff)
    {
        if (sensor device is intelligent (ex. HID))
        {
            HIDSensorPollData(sensorID)

            // a poll response by the sensor device will happen asynchronously
            // the sensor device responds to this poll request by sending an
            // input packed, and this is received in the
            // DriverHandleAsyncDataEvent() just as any other data packet
            // is received
        }
        else if (sensor device is simple (ex. SPB))
        {
            currentDatafields[] = SpbSensorPollData(sensorID)

            // ** TODO: Data is not updated asynchronously when polled
            // ** via SPB. Datafields[] must be assigned similarly to
            // ** DDIHandleAsyncDataEvent() when that logic has been
            // ** finalized. A shared helper method is likely best.
        }
        else if (sensor device is fusion)
        {
            //handle fusion sensor
        }
        else //is some other kind of sensor
        {
            //special action
        }
    }
    else
    {
        // datafields are being updated by events
        // (i.e. DDIHandleAsyncDataEvent)
    }
}