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#!/usr/bin/python
#
# Module: ina260.py
#
# Description: This module acts as an interface between the INA260 sensor
# and downstream applications that use the data. Class methods get
# current, voltage, and power data from the INA260 sensor. It acts as a
# library module that can be imported into and called from other Python
# programs.
#
# Copyright 2021 Jeff Owrey
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see http://www.gnu.org/license.
#
# Revision History
# * v10 released 01 June 2021 by J L Owrey; first release
#
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# Import the I2C interface library
import smbus
import time
# Define Device Registers
CONFIG_REG = 0x0
ID_REG = 0xFE
CUR_REG = 0x1
VOLT_REG = 0x2
PWR_REG = 0x3
class ina260:
# Initialize the INA260 sensor at the supplied address (default
# address is 0x40), and supplied bus (default is 1). Creates
# a new SMBus object for each instance of this class. Writes
# configuration data (two bytes) to the INA260 configuration
# register.
def __init__(self, sAddr=0x40, sbus=1):
# Instantiate a smbus object
self.sensorAddr = sAddr
self.bus = smbus.SMBus(sbus)
# Initialize INA260 sensor. See the data sheet for meaning of
# each bit. The following bytes are written to the configuration
# register
# byte 1: 01100000
# byte 2: 00100111
initData = [0x60, 0x27]
self.bus.write_i2c_block_data(self.sensorAddr, CONFIG_REG, initData)
## end def
def status(self):
# Read configuration data
mfcid = self.bus.read_i2c_block_data(self.sensorAddr, ID_REG, 2)
mfcidB1 = format(mfcid[0], "08b")
mfcidB2 = format(mfcid[1], "08b")
# Read configuration data
config = self.bus.read_i2c_block_data(self.sensorAddr, CONFIG_REG, 2)
configB1 = format(config[0], "08b")
configB2 = format(config[1], "08b")
return (mfcidB1, mfcidB2, configB1, configB2)
## end def
def getCurrent(self):
# Get the current data from the sensor.
# INA260 returns the data in two bytes formatted as follows
# -------------------------------------------------
# bit | b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 |
# -------------------------------------------------
# byte 1 | d15 | d14 | d13 | d12 | d11 | d10 | d9 | d8 |
# -------------------------------------------------
# byte 2 | d7 | d6 | d5 | d4 | d3 | d2 | d1 | d0 |
# -------------------------------------------------
# The current is returned in d15-d0, a two's complement,
# 16 bit number. This means that d15 is the sign bit.
data=self.bus.read_i2c_block_data(self.sensorAddr, CUR_REG, 2)
# Format into a 16 bit word.
bdata = data[0] << 8 | data[1]
# Convert from two's complement to integer.
# If d15 is 1, the the number is a negative two's complement
# number. The absolute value is 2^15 - 1 minus the value
# of d14-d0 taken as a positive number.
if bdata > 0x7FFF:
bdata = -(0xFFFF - bdata) # 0xFFFF is 2^15 - 1
# Convert integer data to mAmps.
mAmps = bdata * 1.25 # LSB is 1.25 mA
return mAmps
## end def
def getVoltage(self):
# Get the voltage data from the sensor.
# INA260 returns the data in two bytes formatted as follows
# -------------------------------------------------
# bit | b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 |
# -------------------------------------------------
# byte 1 | d15 | d14 | d13 | d12 | d11 | d10 | d9 | d8 |
# -------------------------------------------------
# byte 2 | d7 | d6 | d5 | d4 | d3 | d2 | d1 | d0 |
# -------------------------------------------------
# The voltage is returned in d15-d0 as an unsigned integer.
data=self.bus.read_i2c_block_data(self.sensorAddr, VOLT_REG, 2)
# Convert data to volts.
volts = (data[0] << 8 | data[1]) * 0.00125 # LSB is 1.25 mV
return volts
## end def
def getPower(self):
# Get the wattage data from the sensor.
# INA260 returns the data in two bytes formatted as follows
# -------------------------------------------------
# bit | b7 | b6 | b5 | b4 | b3 | b2 | b1 | b0 |
# -------------------------------------------------
# byte 1 | d15 | d14 | d13 | d12 | d11 | d10 | d9 | d8 |
# -------------------------------------------------
# byte 2 | d7 | d6 | d5 | d4 | d3 | d2 | d1 | d0 |
# -------------------------------------------------
# The wattage is returned in d15-d0 as an unsigned integer.
data=self.bus.read_i2c_block_data(self.sensorAddr, PWR_REG, 2)
# Convert data to milliWatts.
mW = (data[0] << 8 | data[1]) * 10.0 # LSB is 10.0 mW
return mW
## end def
## end class
def test():
# Initialize the smbus and INA260 sensor.
pwr1 = ina260(0x40, 1)
# Read the INA260 configuration register and manufacturer's ID.
data = pwr1.status()
print "manufacturer ID: %s %s\nconfiguration register: %s %s\n" % data
# Print out sensor values.
while True:
print "%6.2f mA" % pwr1.getCurrent()
print "%6.2f V" % pwr1.getVoltage()
print "%6.2f mW\n" % pwr1.getPower()
time.sleep(2)
## end def
if __name__ == '__main__':
test()
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