Aurelian Ioan
Published

DIY Power Logger Using I2C & Python

Make your own power logger for electronics that you use in the house using INA219 chip, SSD1306 OLED display, Raspberry Pi 3, and Python.

BeginnerFull instructions provided8 hours1,257
DIY Power Logger Using I2C & Python

Things used in this project

Hardware components

Raspberry Pi 3 Model B
Raspberry Pi 3 Model B
×1
Adafruit INA219 Current Sensor
×1
Adafruit MONOCHROME 0.96" 128X64 OLED GRAPHIC DISPLAY
×1
Jumper wires (generic)
Jumper wires (generic)
×1
Resistor 10k ohm
Resistor 10k ohm
×1
LED (generic)
LED (generic)
×1

Story

Read more

Schematics

Fritzing Sketch

10K resistor setup

Data & graphs for 10K resistor

LED setup

Data & graphs for LED setup

FTDI setup

Data & graph for FTDI breakout board

Code

Source code

Python
Python source code file. First the OLED displaying is configured then in the while loop data is read periodically from the sensors & appended in the .xlsx file.
import time

from Adafruit_SSD1306 import SSD1306_128_64
from ina219 import INA219
from ina219 import DeviceRangeError
from time import sleep

from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont

from openpyxl import Workbook
from openpyxl.chart import LineChart, ScatterChart
from openpyxl.chart import Reference, Series

# INA219 shunt value & reset pin for SSD1306 display
SHUNT_OHMS = 0.1
RST = None

# 128x64 display with hardware I2C:
disp = SSD1306_128_64(rst=RST)

# Initializa libray
disp.begin()

# Clear display
disp.clear()
disp.display()

# Create blank image for drawing.
# Make sure to create image with mode '1' for 1-bit color.
image = Image.new('1', (disp.width, disp.height))

# Get drawing object to draw on image.
draw = ImageDraw.Draw(image)

# Draw a black filled box to clear the image.
draw.rectangle((0,0,disp.width,disp.height), outline=0, fill=0)

# Padding for text aligment. This can be used or not
padding = -2
top = padding
bottom = disp.height - padding
x = 0
font = ImageFont.load_default()

# Configure INA219 sensor
ina = INA219(SHUNT_OHMS)
ina.configure()

# Load Minecraftia-Regular.ttf font file (should be in the same folder
# with the script
font = ImageFont.truetype('Minecraftia-Regular.ttf', 8)
print("Press Ctrl+C to quit.")
sleep(3)

# Create Workbook
wb = Workbook()
ws = wb.active
ws.title =  'Sensor Output'
ws['A1'] = 'Bus Voltage (V)'
ws['B1'] = 'Bus current (mA)'
ws['C1'] = 'Power (mW)'
ws['D1'] = 'Shunt Voltage (mV)'
ws['E1'] = 'Load Voltage (V)'

try:
        while True:
                # Draw a black filled box to clear the image.
                draw.rectangle((0,0,disp.width,disp.height), outline=0, fill=0)

                # Round floating
                bus_V = round(ina.voltage(), 5)
                bus_I = round(ina.current(), 5)
                power = round(ina.power(), 5)
                shunt_V = round(ina.shunt_voltage(), 5)
                load_V  = round((bus_V + (shunt_V/1000)), 5)
                
                print("bus voltage: %s V" % bus_V)
                print("bus current: %s mA" % bus_I)
                print("power: %s mW" % power)
                print("shunt voltage: %s mV" % shunt_V)
                print("load voltage: %s V\n" % load_V)

                # Draw information on the OLED screen
                draw.text((x, top), "INA219 Current Sensor", font=font, fill=255)
                draw.text((x, top+8),  "#####################", font=font, fill=255)
                draw.text((x, top+16), "Bus V: " + str(bus_V) + " V", font=font, fill=255)
                draw.text((x, top+24), "Bus Curr: " + str(bus_I) + " mA", font=font, fill=255)
                draw.text((x, top+32), "Power: " + str(power) + " mW", font=font, fill=255)
                draw.text((x, top+40), "Shunt V: " + str(shunt_V) + " mV" , font=font, fill=255)
                draw.text((x, top+48), "Load V: " + str(load_V) + " V", font=font, fill=255)
                draw.text((x, top+56), "#####################", font=font, fill=255)

                disp.image(image)
                disp.display()
                sleep(.1)
                # Append values to Workbook
                ws.append([bus_V, bus_I, power, shunt_V, load_V])
                
except DeviceRangeError as e:
# Current out of device range with specified shunt resistor
        print e

except KeyboardInterrupt as e:
        print("\nProgram closed")

finally:
        # Draw a black filled box to clear the image.
        draw.rectangle((0,0,disp.width,disp.height), outline=0, fill=0)
        disp.image(image)
        disp.display()

        # Create line chart for Load Voltage
        c1 = LineChart()
        c1.title = "Load Voltage"
        c1.style = 13
        c1.y_axis.title = 'V'
        c1.x_axis.title = 'Row index'
        data = Reference(ws, min_col=5, min_row=1, max_col=5, max_row=ws.max_row)
        c1.add_data(data, titles_from_data=True)
        # Add chart to Workbook
        ws.add_chart(c1, 'H4')

        # Create line chart for Bus current
        c2 = LineChart()
        c2.title = "Bus current"
        c2.style = 13
        c2.y_axis.title = "mA"
        c2.x_axis.title = "Row Index"
        data = Reference(ws, min_col=2, min_row=1, max_col=2, max_row=ws.max_row)
        c2.add_data(data, titles_from_data=True)
        # Add chart to Workbook
        ws.add_chart(c2, 'H20')

        # Create line chart for Power consumption
        c3 = LineChart()
        c3.title = "Power"
        c3.style = 13
        c3.y_axis.title = "mW"
        c3.x_axis.title = "Row Index"
        data = Reference(ws, min_col=3, min_row=1, max_col=3, max_row=ws.max_row)
        c3.add_data(data, titles_from_data=True)
        # Add chart to Workbook
        ws.add_chart(c3, 'H36')

        # Save Workbook
        wb.save('Power Logger_' + time.strftime('%d_%b_%Y_%H_%M_%S') +'.xlsx')

Minecraft font file

Textile
This is the tff file loaded in the script. It has to be in the same folder with the script.
No preview (download only).

Credits

Aurelian Ioan

Aurelian Ioan

2 projects • 7 followers
Thanks to GreatScott!.

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