u/Upper-East8842

Quick demo — cables are still a mess but the PCB is almost done. It’s getting closer 👀

Big progress! Eyes are finished and the pin mechanism is working. Exterior is basically done now — time to work on the internals 🔧 More updates coming soon 👀

If you have any suggestions, feel free to drop them below! 💬

Finally tested the LEDs — starting to look like the real thing! Still a lot to do but it’s coming together 🔧
Note: couldn’t quite nail the green color yet 😅
More updates coming soon!

Hi everyone,

I am designing a custom integrated power and driver board that will control an external DC motor and some addressable LEDs (WS2812B) using an ATtiny84A microcontroller. I've finished the schematic, but before moving on to the PCB layout and hitting the order button, I would really appreciate a thorough review to make sure I haven't missed any critical hardware flaws.

Project Details & Goals:

• Charging: The board utilizes a TP4056 to charge the batteries via a USB-C input.
• Battery: To save board space and keep it lightweight, I am using self-protected Li-Po batteries. Therefore, there is no discrete DW01/FS8205 protection circuit on the schematic.
• Boost Regulator: My goal is a stable 5.1V power rail (P+) for both the MCU and the loads. I set the MT3608 feedback resistors to R3​=43 kΩ and R4​=10 kΩ to achieve this target voltage.
• Microcontroller: An ATtiny84A handles the logic and is powered directly from the 5.1V (P+) rail.
• Motor Driver Layer: The DC motor will be wired externally, so I used Test Points (TP4 & TP5) as solder pads. I am using an AO3400A N-Channel MOSFET for low-side switching.
• Protection & Current Sensing: To suppress inductive voltage spikes, an SS14 flyback diode (D1) is placed in parallel across the motor solder pads. Additionally, to monitor the motor current via the MCU's ADC pin (PA2), I implemented a 500 mΩ shunt resistor followed by a low-pass RC filter (1 kΩ / 1μF).

The full schematic is attached below. Could you please check if there are any short circuits, floating nets, or design flaws, particularly around the MOSFET pins, the MCU reset/power lines, or the MT3608 loop?

Thank you so much for your time and expertise!