Single USB port variant of the Tumbler 2 redesign, optimized for maximum cost reduction.
| Original Design | Redesign Improvement |
|---|---|
| Unfused battery supply | Add slow-blow fuse directly at connector |
| 5 V to 3.3 V LDO regulator | 5 V to 3.3 V buck converter |
| WROOM module with ESP32-D0WD-V3 | WROOM module with ESP32-S3 |
| CH340 for USB-UART Bridge | Directly connect to ESP32 DP/DN |
| 100 nF capacitors on BTN and GPIO0 | Removed unnecessary capacitors on BTN and GPIO0 |
| USB-C shield directly to signal GND | Low impedance 100nF to avoid ground loops |
| Use Obsolete MPU6050 breakout module | Use LSM6DSV directly on PCB |
| Use TB6612FNG breakout module | Use 2x TB67H450FNG directly on PCB |
| 5 V ECHO signal directly to ESP32 | Voltage divider to 3.3 V ESP32 GPIO |
| 5 V Encoder signal directly to ESP32 | Voltage divider to 3.3 V ESP32 GPIO |
| No local decoupling for WS2812B LEDs | Added proper local bypass capacitors for WS2812B |
| Idea | Reason |
|---|---|
| On-board charging circuit (IP5306, BQ25887RGER) | Not required. External USB charger included with battery |
| Additional LDO for clean 3.3 V rail | Not necessary. ESP32-WROOM internal VCC/VCCA already tied |
| Layout A | Layout B | Layout C |
|---|---|---|
 Preferred option |
 Left–right separation |
 Looser version of B |