Final Project

Litter Robot EVO

My automatic self cleaning litter of my cats called Litter Robot Classic from Autopets have always his electronic board that finish to fail and I always need to buy new one and replace… after 5th board, I finally buy another litter and put this one on my garage thinking “One day, I will make new electronic with arduino and a few components…” finally I’m now in fabAcademy and try to make it in a better way !

(For the joke, I have also the newer version called Litter Robot 3 and… electronic fails too 3 weeks before final presentation! I know I have to reverse engineering the LR3 after fabAcademy.)

My presentation slide (fullscreen version here)

My presentation video (fullscreen version here)

Some details on latest version of the idea :

For the fabAcademy, in order to finish in time, I focus on offline version. I choose to work in spirals. Here I finish the spiral 1.

Spiral 1 (FabAcademy target) :

  • new front cover
  • SAMD21E board that uses sensors and TFT + touchscreen (use the lolin screen I have at Agrilab)
  • A4953 driver

Spiral 2 :

  • rework electronic on a smaller optimized board after validating PoC on spiral 1
  • find another ILI9341 + XPT2046 touchscreen without wemos dedicated pins (use less space)
  • rework front cover to a thinner one

When spiral 2 will be completed and fully tested, I can launch a first batch.

Spiral 3 and more :

  • work on online addon & cat tracking

BoM (for spiral 1, need less connectors & cables for V2 because I will rework on a AiO board)

Name+5 Qty Price Vendor
Litter Robot (full without electronic panel) 1 reuse
µc ATSAMD21E17A-AUTCT-ND € 1.95 digikey
Wemos LOLIN 2.4” TFT with touchscreen (based on ILI9341 & XPT2046) seems not available anymore, cheaper screen ILI9341 + XPT2046 touchscreen will work the same, specific wemos shield is useless on this project 1 € 8.24 incl. shipping aliexpress
dupont cables € 0.50 digikey
0.1 µF capacitor 1 € 0.34 digikey
10 µF capacitor 1 € 0.35 digikey
2.54mm 1x5 female header 3 € 2.28 digikey
2.54mm 1x4 female header 3 € 1.77 digikey
2.54mm 1x3 female header 2 € 1.22 digikey
2.54mm 1x2 female header 2 € 1.16 digikey
IC REG LDO 3.3V 1A SOT223 1 € 0.43 digikey
1.27mm 2x5 male header 1 € 0.68 digikey
PLA (can also use ABS/PETG etc.) 150g ~ €5.00 colorfabb
Plywood 18x1200x2500mm (for cabinet) 1 € 64.32 local supplier

Cost for V1 : ~ €88,24 This cost not include hardware for next spiral or testing.

All the work on the hardware will be in CC BY NC ND 4.0 Software part will not be published, but I explain many parts of it.

More details on my final project step by step page.

How my project was evaluated?

My cats are the judges. If they use it like before, I success. One week after bring back Litter Robot EVO at home, I can say they love it.


Front Panel STL : litterRobotFascia.stl

I can provide F3D file on request, I can’t upload it here because of size (more than 15MB)

Kicad of SAMD21E board : I call this board AgriLabDos because I have already made the AgriLabUno using SAMD11 and now it’s a board with SAMD21 and I choose to count in spanish (instead of italian like Arduino)

Kicad of motor driver board : this board can be used as add-on for any project that need to drive motors

Litter cabinet with secret tenons fingers (full) :