Class Ina219

Namespace

Pamoja.Sensors

Assembly

Pamoja.Sensors.dll

A Texas Instruments INA219 current, voltage, and power monitor, and a driver for one on an I2C bus.

public sealed class Ina219 : IDisposable

Inheritance

object

Ina219

Implements

IDisposable

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

The static members are the part's datasheet, decoded exactly as the manufacturer specifies, and Ina219.Sim, a part that is not there.

An instance drives one part over an I2cBus: it resets the part, writes the configuration, programs the calibration for the shunt and the current it is sized for, and reads the calibration back, the identity check a part with no id register allows. Each Measure() triggers one shunt and bus conversion. Nothing is sent until Init() or the first Measure().

Constructors

Ina219(I2cBus, byte, uint, uint, uint, Ina219Config?)

Creates a driver for the part at address on bus.

public Ina219(I2cBus bus, byte address, uint shuntMilliohms = 100, uint maxMicroamps = 3200000, uint currentLsbMicroamps = 0, Ina219Config? config = null)

Parameters

bus I2cBus

The bus the part is on.

address byte

BaseAddress plus what A1 and A0 add.

shuntMilliohms uint

The shunt resistance in milliohms; the common breakout's is 100.

maxMicroamps uint

The largest current the shunt will carry, which sets the finest current step.

currentLsbMicroamps uint

A current step to use instead, such as a round 100, or 0 for the finest.

config Ina219Config?

The range, gain, and converter settings, or null for PowerOn.

Exceptions

PamojaException

The native driver could not be created.

Fields

BaseAddress

The address with A1 and A0 tied to ground; the pins add to it.

public const byte BaseAddress = 64

Field Value

byte

ConfigReset

The configuration register's power-on value.

public const ushort ConfigReset = 14751

Field Value

ushort

Properties

CalibrationWord

The calibration word the driver programs.

public ushort CalibrationWord { get; }

Property Value

ushort

CurrentLsbMicroamps

The current step the driver programs, in microamps per count.

public uint CurrentLsbMicroamps { get; }

Property Value

uint

Methods

AdcConversionMicros(Adc)

Returns how long one conversion takes at a converter setting.

public static uint AdcConversionMicros(Ina219.Adc adc)

Parameters

adc Ina219.Adc

The setting.

Returns

uint

The time in microseconds, from the datasheet's table.

Address(AddressPin, AddressPin)

Returns the 7-bit address the A1 and A0 pins select, from Table 1 of the datasheet.

public static byte Address(Ina219.AddressPin a1, Ina219.AddressPin a0)

Parameters

a1 Ina219.AddressPin

What the A1 pin is tied to.

a0 Ina219.AddressPin

What the A0 pin is tied to.

Returns

byte

The address, 0x40 to 0x4F.

Exceptions

PamojaException

A pin code is not one of the four levels.

BusMillivolts(ushort)

Converts a raw bus-voltage register to millivolts.

public static uint BusMillivolts(ushort raw)

Parameters

raw ushort

The register value.

Returns

uint

The bus voltage.

BusRegister(uint)

Builds the bus-voltage register a monitor reports for a bus voltage.

public static ushort BusRegister(uint millivolts)

Parameters

millivolts uint

The bus voltage in millivolts.

Returns

ushort

The register value, with the conversion-ready flag set.

Calibration(uint, uint)

Computes the calibration register for a shunt and resolution.

public static ushort Calibration(uint currentLsbMicroamps, uint shuntMilliohms)

Parameters

currentLsbMicroamps uint

The microamps per count wanted.

shuntMilliohms uint

The shunt resistor value.

Returns

ushort

The register value to write.

ConfigBits(Ina219Config)

Assembles the configuration register value.

public static ushort ConfigBits(Ina219Config config)

Parameters

config Ina219Config

The settings.

Returns

ushort

The register value to write.

ConfigFromBits(ushort)

Parses a configuration register value.

public static Ina219Config ConfigFromBits(ushort bits)

Parameters

bits ushort

The register value, as read from the part.

Returns

Ina219Config

The settings. Every value decodes.

ConversionMicros(Ina219Config)

Returns how long one conversion cycle takes: the shunt and bus conversions the mode runs.

public static uint ConversionMicros(Ina219Config config)

Parameters

config Ina219Config

The settings.

Returns

uint

The time in microseconds.

ConversionReady(ushort)

Reports whether a bus-voltage register says a conversion is ready.

public static bool ConversionReady(ushort raw)

Parameters

raw ushort

The register value.

Returns

bool

Whether the conversion-ready flag is set.

CurrentMicroamps(short, uint)

Converts a raw current register to microamps.

public static int CurrentMicroamps(short raw, uint currentLsbMicroamps)

Parameters

raw short

The signed register value.

currentLsbMicroamps uint

The resolution the calibration selected.

Returns

int

The current.

CurrentRegister(int, uint)

Builds the current register a monitor reports for a current.

public static short CurrentRegister(int microamps, uint currentLsbMicroamps)

Parameters

microamps int

The current in microamps.

currentLsbMicroamps uint

The current LSB the calibration was set for.

Returns

short

The signed register value.

Dispose()

Releases the driver and its share of the bus.

public void Dispose()

GainRangeMillivolts(Gain)

Returns the shunt-voltage range a gain selects.

public static ushort GainRangeMillivolts(Ina219.Gain gain)

Parameters

gain Ina219.Gain

The gain.

Returns

ushort

The range in millivolts either side of zero.

Init()

Resets the part and programs the configuration and calibration.

public void Init()

Exceptions

PamojaException

Nothing answered, or the calibration did not read back.

MathOverflow(ushort)

Reports whether a bus-voltage register flags a math overflow.

public static bool MathOverflow(ushort raw)

Parameters

raw ushort

The register value.

Returns

bool

Whether the current and power readings are meaningless, which means the calibration needs revisiting.

Measure()

Triggers one shunt and bus conversion and reads every result, initializing the part first if needed.

public Ina219Reading Measure()

Returns

Ina219Reading

The registers as read, and what they mean.

Exceptions

PamojaException

As Init(), and when the conversion-ready flag never sets.

MinimumCurrentLsbMicroamps(uint)

Returns the smallest resolution that still covers a maximum.

public static uint MinimumCurrentLsbMicroamps(uint maxExpectedMicroamps)

Parameters

maxExpectedMicroamps uint

The largest current measured.

Returns

uint

The minimum current LSB in microamps.

PowerMicrowatts(ushort, uint)

Converts a raw power register to microwatts.

public static uint PowerMicrowatts(ushort raw, uint currentLsbMicroamps)

Parameters

raw ushort

The register value.

currentLsbMicroamps uint

The resolution the calibration selected.

Returns

uint

The power. The power LSB is fixed at twenty times the current LSB.

PowerRegister(uint, uint)

Builds the power register a monitor reports for a power.

public static ushort PowerRegister(uint microwatts, uint currentLsbMicroamps)

Parameters

microwatts uint

The power in microwatts.

currentLsbMicroamps uint

The current LSB the calibration was set for.

Returns

ushort

The register value.

ShuntMicrovolts(short)

Converts a raw shunt-voltage register to microvolts.

public static int ShuntMicrovolts(short raw)

Parameters

raw short

The signed register value.

Returns

int

The shunt voltage.

ShuntRegister(int)

Builds the shunt-voltage register a monitor reports for a shunt voltage.

public static short ShuntRegister(int microvolts)

Parameters

microvolts int

The shunt voltage in microvolts.

Returns

short

The signed register value, at 10 uV per count.

Remarks

The inverse of ShuntMicrovolts(short), so a node can be written and tested against what a monitor sends without one attached.