This is a scale meant for weighting our dogs and maybe suitcases by using 4 3-wire load cells connected to an amplifier HX711 and displaying the code to a 16x2 LCD screen with an included I2C backpack to control it. I also made a Youtube video about this project, in case you want to see the final result, including a nice wooden platform. You can watch the video here.

The micro-controller was initially an Arduino Uno / Diavolino model but since there were many pins not being used, and I did not want to use my entire Arduino for this, I decided to miniaturize this project by using an ATtiny85 chip. It has just the right amount of pins for this and the size is very conservative.

This sketch contains the code I used for the Arduino Uno.There is a chance it is behind the ATtiny85 version since I switched over to that chip to complete things. However, the code is super short, so differences will be minuscule.

This sketch is to be used with the ATtiny85 version of the scale.

I will try to maintain both versions (Arduino and ATtiny85) working and synched to each other but the final objective is that the ATtiny85 will be the chip of choice. I used one of the examples of the HX711 library as started code and modified it to suit my needs. There are some functions that I also used from online forums and the like. If I find the links again, I will add them to the coode.

I will do my best keep this updated with all components used for the main part of the project but also for extra related activities.

Edit: I'll go ahead and add some Amazon affiliate links so you can find the components more easily. If you end up buying something, I will get a comission but it will not come at an extra cost to you. It is a way to support more projects like this. Thanks.

Main Project Stuff:

• HX711 amplifier for load cell sensors
• 4 50kg 3-wire load cells (one on each corner of a square) connected together
• One old PC beeper or piezo speaker (for simple sounds when turning on)
• Arduino Uno / Diavolino / ATtiny85
• 16x2 LCD screen with an included I2C backpack (with 0x27 address but that's just my particular component)
• Power source (a portable usb battery in my case)
• USB cable for power
  • In my case, my Diavolino needs an FTDI breakout board to connect through a usb cable.

Other obvious things to have are:

• Jumper wires
• Soldering kit
• A base where to set the sensors
• Housing for the components

Other Components:

• 10 uF capacitor (for when using Arduino Uno as ISP to program ATtiny85 or burn its bootloader)