/// <summary>
/// Resets the device, updates PROM data and clears current measurements
/// </summary>
public virtual void Reset()
{
// Send reset command
Hardware.WriteJoinByte((byte)Ms5611Command.Reset, 0);
// Wait for completion
Task.Delay(TimeSpanExtensions.FromMicroseconds(ResetTime)).Wait();
// Update PROM values
ReadProm();
// Clear measurement
Measurement = Ms5611Measurement.Zero;
}
/// <summary>
/// Calculates the <see cref="Measurement"/> by applying the <see cref="Prom"/>
/// coefficients and other rules to the raw measurements.
/// </summary>
protected virtual void Calculate(int rawPressure, int rawTemperature)
{
// Constants for calculation
const double temperatureAt20C = 2000;
const double temperatureAt15C = 1500;
const double temperatureAtMinus15C = -1500;
const double scale2Power7 = 128;
const double scale2Power8 = 256;
const double scale2Power15 = 32768;
const double scale2Power16 = 65536;
const double scale2Power21 = 2097152;
const double scale2Power23 = 8388608;
const double scale2Power31 = 2147483648;
// First order pressure and temperature calculation...
// Calculate reference temperature
var referenceTemperature = Prom.C5TemperatureReference * scale2Power8;
// Difference between actual and reference temperature
var deltaTemperature = rawTemperature - referenceTemperature;
// Actual temperature (-40...85°C with 0.01°C resolution)
var temperature = temperatureAt20C + deltaTemperature *
Prom.C6TemperatureSensitivity / scale2Power23;
// Calculate temperature compensated pressure
// Offset at actual temperature
var offset = Prom.C2PressureOffset * scale2Power16 +
(Prom.C4TemperatureFromPressureOffset * deltaTemperature) / scale2Power7;
// Sensitivity at actual temperature
var sensitivity = Prom.C1PressureSensitivity * scale2Power15 +
(Prom.C3TemperatureFromPressureSensitivity * deltaTemperature) / scale2Power8;
// Second order temperature compensation...
if (temperature < temperatureAt20C)
{
// Low temperature
var temperature2 = Math.Pow(deltaTemperature, 2) / scale2Power31;
var offset2 = 5 * Math.Pow(temperature - temperatureAt20C, 2) / 2;
var sensitivity2 = offset2 / 2;
if (temperature < temperatureAtMinus15C)
{
// Very low temperature
var temperaturePlus15CSquared = Math.Pow(temperature + temperatureAt15C, 2);
offset2 = offset2 + 7 * temperaturePlus15CSquared;
sensitivity2 = sensitivity2 + 11 * temperaturePlus15CSquared / 2;
}
temperature -= temperature2;
offset -= offset2;
sensitivity -= sensitivity2;
}
// Temperature compensated pressure (10...1200mbar with 0.01mbar resolution)
var pressure = (rawPressure * sensitivity / scale2Power21 - offset) / scale2Power15;
// Correct floating point to whole values and save in properties
Measurement = new Ms5611Measurement(pressure / 100, temperature / 100);
}
/// <summary>
/// Calculates the <see cref="Measurement"/> by applying the <see cref="Prom"/>
/// coefficients and other rules to the raw measurements.
/// </summary>
protected virtual void Calculate(int rawPressure, int rawTemperature)
{
// Constants for calculation
const double temperatureAt20C = 2000;
const double temperatureAt15C = 1500;
const double temperatureAtMinus15C = -1500;
const double scale2Power7 = 128;
const double scale2Power8 = 256;
const double scale2Power15 = 32768;
const double scale2Power16 = 65536;
const double scale2Power21 = 2097152;
const double scale2Power23 = 8388608;
const double scale2Power31 = 2147483648;
// First order pressure and temperature calculation...
// Calculate reference temperature
var referenceTemperature = Prom.C5TemperatureReference * scale2Power8;
// Difference between actual and reference temperature
var deltaTemperature = rawTemperature - referenceTemperature;
// Actual temperature (-40...85°C with 0.01°C resolution)
var temperature = temperatureAt20C + deltaTemperature *
Prom.C6TemperatureSensitivity / scale2Power23;
// Calculate temperature compensated pressure
// Offset at actual temperature
var offset = Prom.C2PressureOffset * scale2Power16 +
(Prom.C4TemperatureFromPressureOffset * deltaTemperature) / scale2Power7;
// Sensitivity at actual temperature
var sensitivity = Prom.C1PressureSensitivity * scale2Power15 +
(Prom.C3TemperatureFromPressureSensitivity * deltaTemperature) / scale2Power8;
// Second order temperature compensation...
if (temperature < temperatureAt20C)
{
// Low temperature
var temperature2 = Math.Pow(deltaTemperature, 2) / scale2Power31;
var offset2 = 5 * Math.Pow(temperature - temperatureAt20C, 2) / 2;
var sensitivity2 = offset2 / 2;
if (temperature < temperatureAtMinus15C)
{
// Very low temperature
var temperaturePlus15CSquared = Math.Pow(temperature + temperatureAt15C, 2);
offset2 = offset2 + 7 * temperaturePlus15CSquared;
sensitivity2 = sensitivity2 + 11 * temperaturePlus15CSquared / 2;
}
temperature -= temperature2;
offset -= offset2;
sensitivity -= sensitivity2;
}
// Temperature compensated pressure (10...1200mbar with 0.01mbar resolution)
var pressure = (rawPressure * sensitivity / scale2Power21 - offset) / scale2Power15;
// Correct floating point to whole values and save in properties
Measurement = new Ms5611Measurement(pressure / 100, temperature / 100);
}
/// <summary>
/// Updates the display when the <see cref="Device"/> channels change.
/// </summary>
private void OnMeasurementUpdated(object sender, Ms5611Measurement measurement)
{
// Dump statistics to output
WriteOutput(measurement.ToString());
// Add data point to graph
Graph.Add(measurement);
// Update display
DoPropertyChanged(nameof(Device));
DoPropertyChanged(nameof(Graph));
}
