Snack Cart POS
Materials
| Item | Use | Quantity | Price |
|---|---|---|---|
| ESP32-S3-N16R8 dev board (Mingwu) | Main microcontroller — runs the UI, database, and WiFi stack | 1 | $9.00 |
| KMRTM35018-SPI 3.5" 480×320 ILI9488 display | Primary UI display, portrait orientation (touch controller present but unused) | 1 | $9.00 |
| Tactile pushbutton (Up/Down/Left/Right/Enter/Back) | Physical D-pad input, replaces the unused touchscreen | 6 | $1.00 |
| GM65 2D barcode scanner module | Scans employee badges and item barcodes | 1 | $18.00 |
| 16GB microSD card | Holds the database, its five backups, the boot log, and the puzzle files — an old card that was lying around | 1 | $5.00 |
| DS3231SN RTC + CR2032 battery | Keeps the real time through power cuts, so sales are dated correctly | 1 | $3.00 |
| USB wall adapter + USB breakout board | 5V power only, no data | 1 | $4.00 |
| Rocker power switch | The one and only physical switch | 1 | $0.25 |
| Resettable fuse (Littelfuse RXEF250) + bulk and ceramic capacitors | Protects the 5V input and smooths the current spikes from WiFi and the scanner | 1 fuse, several caps | $0.50 |
| PETG filament | The entire enclosure — about 350g at ~$18/kg | 350g | $6.30 |
| Steel shot | Ballast in the base so the cart doesn't tip when the buttons get pressed (~$0.80/lb) | 2 lb | $1.60 |
| Deep-pour epoxy | Locks the steel shot into the base | 1 | $6.00 |
| Plastic primer | About a quarter of an $8 can | 1/4 can | $2.00 |
| Textured spray paint | Hides the print lines — about a quarter of a $10 can | 1/4 can | $2.50 |
| Black hot glue | Grip feet on the bottom, drawn as the mascot fish | a few sticks | $0.25 |
| Paper + staples | The printed manual, folded and stapled into a booklet | a few sheets, 3 staples | $0.25 |
| Total | $68.65 | ||
* All prices are rough estimates at time of build and do not represent exact prices spent, due to bulk ordering and timing.
Tools Used
- PlatformIO / Arduino framework
- TFT_eSPI (Bodmer)
- LVGL 8.4.0
- Sqlite3Esp32
- ESPAsyncWebServer + AsyncTCP
- ArduinoJson
- Python (Slide Free board generator)
- 3D printer
- Soldering iron
- Hot glue gun
- Paper trimmer
- Corner-rounding punch