Overview

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This project uses a QT Py ESP32-S2 running CircuitPython with a NAU7802 to build a food scale that's the perfect size for holding your pet's dry food. A strain gauge is used to measure the weight of a food container on top of the 3D printed platform. It makes for a fun way to see your pet's food consumption over time.

Alphanumeric displays show the current weight in either ounces or grams. They also act as a GUI when calibrating the scale.

Two LED buttons let you interact with the code and help you visualize what is happening during calibration.

This project is not meant to be a perfectly precise scale, but it does do a good job at trend-tracking and letting you know when you're getting low on kibble

Accuracy

By calibrating the NAU7802 properly, you can get some accurate measurements for the items that you're trying to weigh. If your project needs extremely accurate measurements for weight though, then this method might not be a good fit since your readings may be within a small margin of error.

Prerequisite Guides

Parts

Angled shot of small square purple dev board.
What has your favorite Espressif WiFi microcontroller, comes with our favorite connector - the STEMMA QT, a chainable I2C port, and has...
$12.50
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Video of a pair of white hand's trying to bend a strain gauge. The gauge is connected to a breakout board which is also connected to an OLED display on a half-size breadboard. The numbers on the OLED display show high digit numbers.
If you are feeling the stress and strain of modern life a Wheatstone bridge and you want to quantify it, this handy breakout will do the job, no sweat! The Adafruit...
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Angled shot of a Strain Gauge Load Cell - 4 Wires - 20Kg.
A strain gauge is a type of electronic sensor used to measure force or strain (big surprise there). They are made of an insulating flexible backing with a metallic...
$3.95
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Overhead shot of an assembled 14-segment LED backpack, emitting the follow text in yellow LEDS: "AdaFruit 14-Segment Backpack"
Display, elegantly, 012345678 or 9! Gaze, hypnotized, at ABCDEFGHIJKLM - well it can display the whole alphabet. You get the point. This is a nice, bright alphanumeric display that...
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Angled shot of a green 16mm illuminated pushbutton.
A button is a button, and an LED is a LED, but this LED illuminated button is a lovely combination of both! It's a medium sized button, large enough to press easily but not too big...
$1.50
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Angled shot of a blue round 16mm illuminated pushbutton.
A switch is a switch, and an LED is an LED, but this LED illuminated button is a lovely combination of both! It's a medium sized button, large enough to press easily but not too...
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1 x M4 Screws
M4 screws
1 x 45mm M4 screws
45mm M4 screws
1 x Food storage container
2.6 quart storage container
1 x Calibration Weight 1g 2g 5g 10g 20g
Calibration weights
Circuit Diagram 

This guide was first published on Jul 20, 2022. It was last updated on Apr 16, 2024.

This page (Overview) was last updated on Mar 08, 2024.

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