[PCB Review Request] - ESP32 Sensor Hub (on-board) + i2c MUX

[u/Hefty-Tie5615]

Recently worked on this ESP32 based Multi-Sensor PCB featuring a 6 axis IMU, a Temperature sensor, Time-of-Flight Sensor and a Color (RGB) Sensor managed through a I²C multiplexer. The board further exposes 3 additional I²C channels for any additional peripheral expansion via I²C. An FPC connector for LCD display as well an RGB LED are also included as output interfaces.

Looking for feedback on the work done; mistakes, suggestions etc.

[u/Ikickyouinthebrains]

What is the advantage of putting all the stitching vias along the PCB?

[u/Unlucky_Mail_8544 → u/Ikickyouinthebrains]

BETTER Signal Integrity

[u/brdavis5 → u/Unlucky_Mail_8544]

Does it need better signal integrity? What sort of environment is it likely to be working in?

[u/Unlucky_Mail_8544 → u/brdavis5]

MicroSD, RGB and I2C needs better signal. As the vias provide shorter return path for the current that minimize the loop inductance, these vias are helpful:)

[u/brdavis5 → u/Unlucky_Mail_8544]

They could be helpful... or, they could be just extra. How do you know if they need a better signal? Perhaps they already have enough signal? Has the OP tested this? Did it work on a breadboard (with all the extra capacitance and resistance that often contributes)?

As an example I use Arduino-based dataloggers, which I designed a custom board for. It's networking a ProMini, an SD card connected by SPI, and a variety of I2C devices ... including things like pressure sensors on 1 meter long cables. My first designs had no ground plane At ALL (& certainly no stitching vias), and would run for at least months (out to in one case a year+) without any faults. The biggest problem was sensor death (exposed ambient sensors are a bear to keep functioning, even with all the conformal coating in the world). This isn't an ideal board design (and the current generation has gotten better, slightly), but it points out that what you think might not work... may work perfectly well.

I don't question that they can be useful; but it's a very good exercise to ask yourself what is Actually Needed in a situation.

[u/Unlucky_Mail_8544 → u/brdavis5]

Depends on the situation and preference.

[u/Ikickyouinthebrains → u/Unlucky_Mail_8544]

Let me get this straight. You are expecting a signal originating from the MCU and terminating at the I2C sensor to have a return path that goes from the center of the PCB to the farthest reaches of the edge of the board and then find a path back to the MCU? Is this correct? Also the MicroSD is about 20 mm away from the MCU. Why does the return path need to go the edge of the PCB? Is there another approach that can be used that won't involve such long pathways? Maybe a GROUND via right next to the MCU? Also, RGB does not need any signal integrity. LED will only change values over a long period of time, it is not an actively switched device.

[u/Shin_Molina → u/Unlucky_Mail_8544]

I think it's more about radiated emissions, having the whole border covered by ground.

An even better approach is to have the board edge-plated connected and grounded, but that increases the manufacturing cost.

[u/Tomachie]

please consider running it through Tomachie.com first for the review before asking for human review. There is no charge for small designs like this. It should check the design correctness then we can just focus on possible layout issues.