Source code for adafruit_ina219

# SPDX-FileCopyrightText: 2017 Dean Miller for Adafruit Industries
#
# SPDX-License-Identifier: MIT

"""
`adafruit_ina219`
====================================================

CircuitPython driver for the INA219 current sensor.

* Author(s): Dean Miller

Implementation Notes
--------------------

**Hardware:**

* `Adafruit INA219 High Side DC Current Sensor Breakout <https://www.adafruit.com/product/904>`_

* `Adafruit INA219 FeatherWing <https://www.adafruit.com/product/3650>`_

**Software and Dependencies:**

* Adafruit CircuitPython firmware (2.2.0+) for the ESP8622 and M0-based boards:
  https://github.com/adafruit/circuitpython/releases
* Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
"""

from micropython import const
from adafruit_bus_device.i2c_device import I2CDevice

from adafruit_register.i2c_struct import ROUnaryStruct, UnaryStruct
from adafruit_register.i2c_bits import ROBits, RWBits
from adafruit_register.i2c_bit import ROBit

__version__ = "0.0.0-auto.0"
__repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_INA219.git"

# Bits
# pylint: disable=too-few-public-methods

# Config Register (R/W)
_REG_CONFIG = const(0x00)


[docs]class BusVoltageRange: """Constants for ``bus_voltage_range``""" RANGE_16V = 0x00 # set bus voltage range to 16V RANGE_32V = 0x01 # set bus voltage range to 32V (default)
[docs]class Gain: """Constants for ``gain``""" DIV_1_40MV = 0x00 # shunt prog. gain set to 1, 40 mV range DIV_2_80MV = 0x01 # shunt prog. gain set to /2, 80 mV range DIV_4_160MV = 0x02 # shunt prog. gain set to /4, 160 mV range DIV_8_320MV = 0x03 # shunt prog. gain set to /8, 320 mV range
[docs]class ADCResolution: """Constants for ``bus_adc_resolution`` or ``shunt_adc_resolution``""" ADCRES_9BIT_1S = 0x00 # 9bit, 1 sample, 84us ADCRES_10BIT_1S = 0x01 # 10bit, 1 sample, 148us ADCRES_11BIT_1S = 0x02 # 11 bit, 1 sample, 276us ADCRES_12BIT_1S = 0x03 # 12 bit, 1 sample, 532us ADCRES_12BIT_2S = 0x09 # 12 bit, 2 samples, 1.06ms ADCRES_12BIT_4S = 0x0A # 12 bit, 4 samples, 2.13ms ADCRES_12BIT_8S = 0x0B # 12bit, 8 samples, 4.26ms ADCRES_12BIT_16S = 0x0C # 12bit, 16 samples, 8.51ms ADCRES_12BIT_32S = 0x0D # 12bit, 32 samples, 17.02ms ADCRES_12BIT_64S = 0x0E # 12bit, 64 samples, 34.05ms ADCRES_12BIT_128S = 0x0F # 12bit, 128 samples, 68.10ms
[docs]class Mode: """Constants for ``mode``""" POWERDOWN = 0x00 # power down SVOLT_TRIGGERED = 0x01 # shunt voltage triggered BVOLT_TRIGGERED = 0x02 # bus voltage triggered SANDBVOLT_TRIGGERED = 0x03 # shunt and bus voltage triggered ADCOFF = 0x04 # ADC off SVOLT_CONTINUOUS = 0x05 # shunt voltage continuous BVOLT_CONTINUOUS = 0x06 # bus voltage continuous SANDBVOLT_CONTINUOUS = 0x07 # shunt and bus voltage continuous
# SHUNT VOLTAGE REGISTER (R) _REG_SHUNTVOLTAGE = const(0x01) # BUS VOLTAGE REGISTER (R) _REG_BUSVOLTAGE = const(0x02) # POWER REGISTER (R) _REG_POWER = const(0x03) # CURRENT REGISTER (R) _REG_CURRENT = const(0x04) # CALIBRATION REGISTER (R/W) _REG_CALIBRATION = const(0x05) # pylint: enable=too-few-public-methods def _to_signed(num): if num > 0x7FFF: num -= 0x10000 return num
[docs]class INA219: """Driver for the INA219 current sensor""" # Basic API: # INA219( i2c_bus, addr) Create instance of INA219 sensor # :param i2c_bus The I2C bus the INA219is connected to # :param addr (0x40) Address of the INA219 on the bus (default 0x40) # shunt_voltage RO : shunt voltage scaled to Volts # bus_voltage RO : bus voltage (V- to GND) scaled to volts (==load voltage) # current RO : current through shunt, scaled to mA # power RO : power consumption of the load, scaled to Watt # set_calibration_32V_2A() Initialize chip for 32V max and up to 2A (default) # set_calibration_32V_1A() Initialize chip for 32V max and up to 1A # set_calibration_16V_400mA() Initialize chip for 16V max and up to 400mA # Advanced API: # config register break-up # reset WO : Write Reset.RESET to reset the chip (must recalibrate) # bus_voltage_range RW : Bus Voltage Range field (use BusVoltageRange.XXX constants) # gain RW : Programmable Gain field (use Gain.XXX constants) # bus_adc_resolution RW : Bus ADC resolution and averaging modes (ADCResolution.XXX) # shunt_adc_resolution RW : Shunt ADC resolution and averaging modes (ADCResolution.XXX) # mode RW : operating modes in config register (use Mode.XXX constants) # raw_shunt_voltage RO : Shunt Voltage register (not scaled) # raw_bus_voltage RO : Bus Voltage field in Bus Voltage register (not scaled) # conversion_ready RO : Conversion Ready bit in Bus Voltage register # overflow RO : Math Overflow bit in Bus Voltage register # raw_power RO : Power register (not scaled) # raw_current RO : Current register (not scaled) # calibration RW : calibration register (note: value is cached) def __init__(self, i2c_bus, addr=0x40): self.i2c_device = I2CDevice(i2c_bus, addr) self.i2c_addr = addr # Set chip to known config values to start self._cal_value = 0 self._current_lsb = 0 self._power_lsb = 0 self.set_calibration_32V_2A() # config register break-up reset = RWBits(1, _REG_CONFIG, 15, 2, False) bus_voltage_range = RWBits(1, _REG_CONFIG, 13, 2, False) gain = RWBits(2, _REG_CONFIG, 11, 2, False) bus_adc_resolution = RWBits(4, _REG_CONFIG, 7, 2, False) shunt_adc_resolution = RWBits(4, _REG_CONFIG, 3, 2, False) mode = RWBits(3, _REG_CONFIG, 0, 2, False) # shunt voltage register raw_shunt_voltage = ROUnaryStruct(_REG_SHUNTVOLTAGE, ">h") # bus voltage register raw_bus_voltage = ROBits(13, _REG_BUSVOLTAGE, 3, 2, False) conversion_ready = ROBit(_REG_BUSVOLTAGE, 1, 2, False) overflow = ROBit(_REG_BUSVOLTAGE, 0, 2, False) # power and current registers raw_power = ROUnaryStruct(_REG_POWER, ">H") raw_current = ROUnaryStruct(_REG_CURRENT, ">h") # calibration register _raw_calibration = UnaryStruct(_REG_CALIBRATION, ">H") @property def calibration(self): """Calibration register (cached value)""" return self._cal_value # return cached value @calibration.setter def calibration(self, cal_value): self._cal_value = ( cal_value # value is cached for ``current`` and ``power`` properties ) self._raw_calibration = self._cal_value @property def shunt_voltage(self): """The shunt voltage (between V+ and V-) in Volts (so +-.327V)""" # The least signficant bit is 10uV which is 0.00001 volts return self.raw_shunt_voltage * 0.00001 @property def bus_voltage(self): """The bus voltage (between V- and GND) in Volts""" # Shift to the right 3 to drop CNVR and OVF and multiply by LSB # Each least signficant bit is 4mV return self.raw_bus_voltage * 0.004 @property def current(self): """The current through the shunt resistor in milliamps.""" # Sometimes a sharp load will reset the INA219, which will # reset the cal register, meaning CURRENT and POWER will # not be available ... always setting a cal # value even if it's an unfortunate extra step self._raw_calibration = self._cal_value # Now we can safely read the CURRENT register! return self.raw_current * self._current_lsb @property def power(self): """The power through the load in Watt.""" # Sometimes a sharp load will reset the INA219, which will # reset the cal register, meaning CURRENT and POWER will # not be available ... always setting a cal # value even if it's an unfortunate extra step self._raw_calibration = self._cal_value # Now we can safely read the CURRENT register! return self.raw_power * self._power_lsb
[docs] def set_calibration_32V_2A(self): # pylint: disable=invalid-name """Configures to INA219 to be able to measure up to 32V and 2A of current. Counter overflow occurs at 3.2A. ..note :: These calculations assume a 0.1 shunt ohm resistor is present """ # By default we use a pretty huge range for the input voltage, # which probably isn't the most appropriate choice for system # that don't use a lot of power. But all of the calculations # are shown below if you want to change the settings. You will # also need to change any relevant register settings, such as # setting the VBUS_MAX to 16V instead of 32V, etc. # VBUS_MAX = 32V (Assumes 32V, can also be set to 16V) # VSHUNT_MAX = 0.32 (Assumes Gain 8, 320mV, can also be 0.16, 0.08, 0.04) # RSHUNT = 0.1 (Resistor value in ohms) # 1. Determine max possible current # MaxPossible_I = VSHUNT_MAX / RSHUNT # MaxPossible_I = 3.2A # 2. Determine max expected current # MaxExpected_I = 2.0A # 3. Calculate possible range of LSBs (Min = 15-bit, Max = 12-bit) # MinimumLSB = MaxExpected_I/32767 # MinimumLSB = 0.000061 (61uA per bit) # MaximumLSB = MaxExpected_I/4096 # MaximumLSB = 0,000488 (488uA per bit) # 4. Choose an LSB between the min and max values # (Preferrably a roundish number close to MinLSB) # CurrentLSB = 0.0001 (100uA per bit) self._current_lsb = 0.1 # Current LSB = 100uA per bit # 5. Compute the calibration register # Cal = trunc (0.04096 / (Current_LSB * RSHUNT)) # Cal = 4096 (0x1000) self._cal_value = 4096 # 6. Calculate the power LSB # PowerLSB = 20 * CurrentLSB # PowerLSB = 0.002 (2mW per bit) self._power_lsb = 0.002 # Power LSB = 2mW per bit # 7. Compute the maximum current and shunt voltage values before overflow # # Max_Current = Current_LSB * 32767 # Max_Current = 3.2767A before overflow # # If Max_Current > Max_Possible_I then # Max_Current_Before_Overflow = MaxPossible_I # Else # Max_Current_Before_Overflow = Max_Current # End If # # Max_ShuntVoltage = Max_Current_Before_Overflow * RSHUNT # Max_ShuntVoltage = 0.32V # # If Max_ShuntVoltage >= VSHUNT_MAX # Max_ShuntVoltage_Before_Overflow = VSHUNT_MAX # Else # Max_ShuntVoltage_Before_Overflow = Max_ShuntVoltage # End If # 8. Compute the Maximum Power # MaximumPower = Max_Current_Before_Overflow * VBUS_MAX # MaximumPower = 3.2 * 32V # MaximumPower = 102.4W # Set Calibration register to 'Cal' calculated above self._raw_calibration = self._cal_value # Set Config register to take into account the settings above self.bus_voltage_range = BusVoltageRange.RANGE_32V self.gain = Gain.DIV_8_320MV self.bus_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.shunt_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.mode = Mode.SANDBVOLT_CONTINUOUS
[docs] def set_calibration_32V_1A(self): # pylint: disable=invalid-name """Configures to INA219 to be able to measure up to 32V and 1A of current. Counter overflow occurs at 1.3A. .. note:: These calculations assume a 0.1 ohm shunt resistor is present""" # By default we use a pretty huge range for the input voltage, # which probably isn't the most appropriate choice for system # that don't use a lot of power. But all of the calculations # are shown below if you want to change the settings. You will # also need to change any relevant register settings, such as # setting the VBUS_MAX to 16V instead of 32V, etc. # VBUS_MAX = 32V (Assumes 32V, can also be set to 16V) # VSHUNT_MAX = 0.32 (Assumes Gain 8, 320mV, can also be 0.16, 0.08, 0.04) # RSHUNT = 0.1 (Resistor value in ohms) # 1. Determine max possible current # MaxPossible_I = VSHUNT_MAX / RSHUNT # MaxPossible_I = 3.2A # 2. Determine max expected current # MaxExpected_I = 1.0A # 3. Calculate possible range of LSBs (Min = 15-bit, Max = 12-bit) # MinimumLSB = MaxExpected_I/32767 # MinimumLSB = 0.0000305 (30.5uA per bit) # MaximumLSB = MaxExpected_I/4096 # MaximumLSB = 0.000244 (244uA per bit) # 4. Choose an LSB between the min and max values # (Preferrably a roundish number close to MinLSB) # CurrentLSB = 0.0000400 (40uA per bit) self._current_lsb = 0.04 # In milliamps # 5. Compute the calibration register # Cal = trunc (0.04096 / (Current_LSB * RSHUNT)) # Cal = 10240 (0x2800) self._cal_value = 10240 # 6. Calculate the power LSB # PowerLSB = 20 * CurrentLSB # PowerLSB = 0.0008 (800uW per bit) self._power_lsb = 0.0008 # 7. Compute the maximum current and shunt voltage values before overflow # # Max_Current = Current_LSB * 32767 # Max_Current = 1.31068A before overflow # # If Max_Current > Max_Possible_I then # Max_Current_Before_Overflow = MaxPossible_I # Else # Max_Current_Before_Overflow = Max_Current # End If # # ... In this case, we're good though since Max_Current is less than MaxPossible_I # # Max_ShuntVoltage = Max_Current_Before_Overflow * RSHUNT # Max_ShuntVoltage = 0.131068V # # If Max_ShuntVoltage >= VSHUNT_MAX # Max_ShuntVoltage_Before_Overflow = VSHUNT_MAX # Else # Max_ShuntVoltage_Before_Overflow = Max_ShuntVoltage # End If # 8. Compute the Maximum Power # MaximumPower = Max_Current_Before_Overflow * VBUS_MAX # MaximumPower = 1.31068 * 32V # MaximumPower = 41.94176W # Set Calibration register to 'Cal' calculated above self._raw_calibration = self._cal_value # Set Config register to take into account the settings above self.bus_voltage_range = BusVoltageRange.RANGE_32V self.gain = Gain.DIV_8_320MV self.bus_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.shunt_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.mode = Mode.SANDBVOLT_CONTINUOUS
[docs] def set_calibration_16V_400mA(self): # pylint: disable=invalid-name """Configures to INA219 to be able to measure up to 16V and 400mA of current. Counter overflow occurs at 1.6A. .. note:: These calculations assume a 0.1 ohm shunt resistor is present""" # Calibration which uses the highest precision for # current measurement (0.1mA), at the expense of # only supporting 16V at 400mA max. # VBUS_MAX = 16V # VSHUNT_MAX = 0.04 (Assumes Gain 1, 40mV) # RSHUNT = 0.1 (Resistor value in ohms) # 1. Determine max possible current # MaxPossible_I = VSHUNT_MAX / RSHUNT # MaxPossible_I = 0.4A # 2. Determine max expected current # MaxExpected_I = 0.4A # 3. Calculate possible range of LSBs (Min = 15-bit, Max = 12-bit) # MinimumLSB = MaxExpected_I/32767 # MinimumLSB = 0.0000122 (12uA per bit) # MaximumLSB = MaxExpected_I/4096 # MaximumLSB = 0.0000977 (98uA per bit) # 4. Choose an LSB between the min and max values # (Preferrably a roundish number close to MinLSB) # CurrentLSB = 0.00005 (50uA per bit) self._current_lsb = 0.05 # in milliamps # 5. Compute the calibration register # Cal = trunc (0.04096 / (Current_LSB * RSHUNT)) # Cal = 8192 (0x2000) self._cal_value = 8192 # 6. Calculate the power LSB # PowerLSB = 20 * CurrentLSB # PowerLSB = 0.001 (1mW per bit) self._power_lsb = 0.001 # 7. Compute the maximum current and shunt voltage values before overflow # # Max_Current = Current_LSB * 32767 # Max_Current = 1.63835A before overflow # # If Max_Current > Max_Possible_I then # Max_Current_Before_Overflow = MaxPossible_I # Else # Max_Current_Before_Overflow = Max_Current # End If # # Max_Current_Before_Overflow = MaxPossible_I # Max_Current_Before_Overflow = 0.4 # # Max_ShuntVoltage = Max_Current_Before_Overflow * RSHUNT # Max_ShuntVoltage = 0.04V # # If Max_ShuntVoltage >= VSHUNT_MAX # Max_ShuntVoltage_Before_Overflow = VSHUNT_MAX # Else # Max_ShuntVoltage_Before_Overflow = Max_ShuntVoltage # End If # # Max_ShuntVoltage_Before_Overflow = VSHUNT_MAX # Max_ShuntVoltage_Before_Overflow = 0.04V # 8. Compute the Maximum Power # MaximumPower = Max_Current_Before_Overflow * VBUS_MAX # MaximumPower = 0.4 * 16V # MaximumPower = 6.4W # Set Calibration register to 'Cal' calculated above self._raw_calibration = self._cal_value # Set Config register to take into account the settings above self.bus_voltage_range = BusVoltageRange.RANGE_16V self.gain = Gain.DIV_1_40MV self.bus_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.shunt_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.mode = Mode.SANDBVOLT_CONTINUOUS
[docs] def set_calibration_16V_5A(self): # pylint: disable=invalid-name """Configures to INA219 to be able to measure up to 16V and 5000mA of current. Counter overflow occurs at 8.0A. .. note:: These calculations assume a 0.02 ohm shunt resistor is present""" # Calibration which uses the highest precision for # current measurement (0.1mA), at the expense of # only supporting 16V at 5000mA max. # VBUS_MAX = 16V # VSHUNT_MAX = 0.16 (Assumes Gain 3, 160mV) # RSHUNT = 0.02 (Resistor value in ohms) # 1. Determine max possible current # MaxPossible_I = VSHUNT_MAX / RSHUNT # MaxPossible_I = 8.0A # 2. Determine max expected current # MaxExpected_I = 5.0A # 3. Calculate possible range of LSBs (Min = 15-bit, Max = 12-bit) # MinimumLSB = MaxExpected_I/32767 # MinimumLSB = 0.0001529 (uA per bit) # MaximumLSB = MaxExpected_I/4096 # MaximumLSB = 0.0012207 (uA per bit) # 4. Choose an LSB between the min and max values # (Preferrably a roundish number close to MinLSB) # CurrentLSB = 0.00016 (uA per bit) self._current_lsb = 0.1524 # in milliamps # 5. Compute the calibration register # Cal = trunc (0.04096 / (Current_LSB * RSHUNT)) # Cal = 13434 (0x347a) self._cal_value = 13434 # 6. Calculate the power LSB # PowerLSB = 20 * CurrentLSB # PowerLSB = 0.003 (3.048mW per bit) self._power_lsb = 0.003048 # 7. Compute the maximum current and shunt voltage values before overflow # # 8. Compute the Maximum Power # # Set Calibration register to 'Cal' calcutated above self._raw_calibration = self._cal_value # Set Config register to take into account the settings above self.bus_voltage_range = BusVoltageRange.RANGE_16V self.gain = Gain.DIV_4_160MV self.bus_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.shunt_adc_resolution = ADCResolution.ADCRES_12BIT_1S self.mode = Mode.SANDBVOLT_CONTINUOUS