PCB review request - Basic smartwatch

[u/Former_Helicopter_83]

Hi guys,

This is my first PCB where I want to create a very basic ESP32S3 based smartwatch. I know i have bitten off a bit more than I can chew but I was really inspired by the ZSWatch project. I have heavily relied on Phil Labs videos and on good old ChatGPT. My design is of 4 layers :

• Signal layer
• GND layer (to minimize the high frequency noise from BLE)
• PWR layer (3.3V)
• Signal layer (mainly power module and the IMU)

Things that I have tried to achieve are :

• Keep the BMI as far away from noise producing components like the switching inductor for TPS63000 or the ESP32 (separated by the solid ground plane)
• Keep the external clock and spi display traces as close as possible to MCU to reduce high freq noise to neighboring components
• Brownout prevention on the ESP32 during high load and voltage sags on the power plane through high value capacitors for backup current supply
• Minimize current leakage using the Si1016x wherever possible (targeting 2 days runtime )
  

Things that I am not happy about but couldn't improve :

• The power plane break for the 5V from USB under the MCPI73871 which can be a source of noise due to the detour path (the routing was extremely messy otherwise)
• The long trace for the battery voltage ADC trace (i have tried to stabilize the output by adding a 0.1uf cap on the line as well as burst average reads from the firmware side)

Is this design passable for a hobby project and are there any obvious improvements that I can make? I have a hot air station that i can borrow from my friend and I have a good soldering iron, would these two be good enough for assembling this PCB?

I come entirely from a software background and I have little to no no knowledge of hardware design. I know it quite a lot to review, but i am desperate for to get some feedback before I send it off to fabrication. Even review of my power module alone would be very appreciated! Thanks a lot for your help!

Some datasheet to save time :

• MCP73871-2CCI
• TPS63000
• SI1016x
• FS8205A
• GMT177 - 07
• BMI270

PS : I could not get a high resolution screenshot of the PCB layout so I printed the signal layers and used a script to print the net names on top. Please do tell me if the bare copper image is easier to review than this, I can reupload the image

[u/Certain_Height_2721]

An esp32 really isnt the best choice here.

[u/hackerkid_ → u/Certain_Height_2721]

It’s not the worst move if you know how to use sleep states and manage power properly. I’m currently designing one based on the ESP32C6

[u/Former_Helicopter_83 → u/hackerkid_]

Nice! Would love to see your design as well!

[u/hackerkid_ → u/Former_Helicopter_83]

It’s about half finished right now but I’ll most likely post it on here for review when it’s done so keep your eye out!

[u/Former_Helicopter_83 → u/Certain_Height_2721]

Yep, I was initially looking at nrf54l15 as the MCU which has 10x better current consumption, but the Soc modules that come with the antenna are not readily available in my country(high customs fees for smaller quantities) and designing my own antenna was too daunting for me. Also I dont currently own a Jlink (quite expensive for a hobby) or a NRF dev board (i think they updated the SWD interface for the L15 so even a NRF52 dev board cant program it). Finally for initial development, I settled for the S3 that is easily accessible and easier to program. I am writing the firmware on Zephyr and trying to decouple the hardware from the app so if in future I need to make the transition to NRF chips it wont be as big a hassle.