Homemade Hardware – Scale board
For this week we had to start prototyping week 8’s board. We had to decide on a concept and start prototyping the board and components for it. After some thought, I decided to either go for a musical instrument, or a weight scale. Given the time scope of the assignment, I decided to go with the weight scale board.
Load cellsSince I decided to go with a weight scale board, I started researching into load cells using Arduinos. I used Sparksfun guide to load cells and amplifiers and this Instructable to get comfortable with the idea of using a load cell. I ordered an HX711 amplifier breakout board and a 100 grams load cell. As the board came without header pins, I started by soldering header pins on the breakout board.
After soldering the the HX711 amp breakout board, I downloaded the HX711 library from the Arduino and connected the load cell to the amp board to the arduino and started measuring. Unfortunately, the load cell didn’t come with threads (screws) and has to be mounted before it could be used accurately because the measurement hits the amplifier (I ordered 3mm threads so I can mount the scale between two laser cut panels I’ll cut).
Designing a board
To get started with designing the board, I found Sparksfun Github repo that has Eagle schematics for the HX711 breakout board, and so I downloaded it and started deleting parts I don’t really need for my board. I also inserted an ATTiny85 into the board got a basic header layout for power and ground, and for the load cell connections.