Device assembly¶
The assembly of the device is quite simple, the screen is placed first with four screws, then the button, and then the rest of the plate that is also placed with screws. The trickiest part is placing the battery charger outlet. I should have put one more screw to make everything perfect.
BOM¶
| Part/Component | Description | Technology | Quantity | Price |
|---|---|---|---|---|
| Microcontroller | Attiny3216 | STD | 1 | €0.85 |
| Cooper board | Copper 35micron | Milling | 1 | €2.34 |
| Accelerometer | MPU6050 | STD | 1 | €6.99 |
| Screen | OLED 128x64 I2C | STD | 1 | €6.99 |
| Bluetooth | HC-10 | STD | 1 | €9,99 |
| Capacitor | Kemet 1UF | STD | 1 | €0,22 |
| Pin Headers | Harwin M22 | STD | 1 | €0,16 |
| Resistors | 1K Yageo | STD | 3 | €2,91 |
| Resistors | 0 Yageo | STD | 4 | €3,48 |
| Battery | battery 3.7V | STD | 1 | €8.41 |
| Battery charger | Sparkfun | STD | 1 | €11.95 |
| LED | SMD WL-SMCW SMDMono | STD | 1 | €0,15 |
| Switch | 6-pin on/off 8x8mm | STD | 1 | €0,30 |
| Internal case | PLA | 3D printed | 2 | ~€4 |
| External case | Silicon + glitter | Molding and casting | 1 | €25.41 |
| Ext. case mold | Wax | Molding and casting | 1 | €18.73 |
| Ext. case mold | PLA | 3D printed | 1 | ~€4 |
| PCB screws | M1.64x3.75mm | STD | 2 | €0.20 |
| Oled screws | M1.4x3.3mm | STD | 4 | €0.40 |
| Case screws | M2x6mm | STD | 2 | €0.20 |
Total: €107.68¶
During the process perform several assembly tests. I ended up deciding that everything had to be just where it fit and that the button should be made wider so that it would have a greater tolerance margin.
It is a prototype but it is quite solid. It is a little bigger than I expected, especially since it has several standard modules, but I think it is easy to miniaturize since it does not have any very complex component and its components have low energy consumption.
