Fluid Simulation Pendant

Fluid Simulation Pendant

A Fluid Simulation Pendant Inspired by Mitxela

Overview

Since January, I've been particularly inspired by Mitxela's Fluid Simulation Pendant. A watch-sized device, it contains it's own charlieplexed LED display driven by an STM32. This allows the device to run a particle simulation that responds to gravity in real time. In other words, water is displayed on it's LED display that flows and settles naturally as you move.

As a beginner, I was thoroughly intrigued. This came at the perfect opportunity as I sought to enter electronic design. So, with no former experience, I set out to build my own from scratch.

You can find my full devlog at Blueprint

PCB

This project was designed in KiCAD. V1 utilized a lilypad design with two 2-layer daughter boards (see devlog). V2 features a singular 4-layer board, merging V1's two daughter boards. It tackles significant issues from V1.

Schematic

PCB

3D View

Setup

OBTAIN PCB

1. Download project files from Github. Use KiCAD to open hardware files.
2. Export & Upload to JLCPCB through Fabrication Toolkit
3. Select PCBA. Make sure you click on Standard + assemble on both sides.
4. Follow on screen instructions. Verify BOM contents.
5. Purchase and await arrival.

While waiting, you can 3D print the case included in the CAD folder. Download both "Case.3mf" and "Back Lid.3mf" Alternatively, you can access the CAD on Onshape

ASSEMBLY

1. Solder PH1 pins on the back of the PCB at drilled holes labeled BOOT0, NRST, DEBUG_TMS, GND, DEBUG_TCK, 3.3V
2. Connect to Nucleo's ST-LINK, Connect to PCB
3. Install STM32CubeProgrammer and STM32CubeIDE
4. Open software folder from downloaded project files, select STM32.ioc (this should open STM32CubeProgrammer)
5. Select generate code (this should open STM32CubeIDE)
6. Replace the generated main.cp or cpp with main.cp from project files, click run to save
7. Install PCB to case - Be CAREFUL! Putting it at an angle with the USB-C pointed towards the opening helps.
8. Plug the battery into PCB's JST-2 port
9. Install the back lid + push in the watch glass

BOM

In order to program this device, you will need F to F Jumper Wire and a Nucleo (I used Nucleo-F446RE). I didn't include these items as you may already have them. Disclaimer: The cost and quantity of PCB components were determined by JLCPCB. JLCPCB sources their components from LCSC, but price may be inaccurate. Likewise, JLCPCB charged more components than required (e.g I only need 1040 Green 0402 LEDs, not 1045) Likewise, you'll need to order 5 PCBs & 2 PCBA minimum. I ordered 5 PCBs + associated PCBA.