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I'm working on a 4-layer PCB design and would appreciate any feedback or recommendations you might have. Here are some key details of the design: -heavy_check_mark: Microcontroller: ESP32-C3FH4 for control and communication -heavy_check_mark: GPS/GPRS Module: SIM808, with SIM card support -heavy_check_mark: Sensors: • MLX90614 for temperature measurement • MPU-9250 for acceleration sensing • APDS-9960 for proximity detection -heavy_check_mark: Power Management: TP4056 module for LiPo battery charging and seamless switching between USB, battery, and external power -heavy_check_mark: Antenna Connections: Separate GSM and GPS antennas for the SIM808

-heavy_check_mark: Layer Configuration:

-heavy_check_mark: 4-Layer Stack: • Top Layer: Signal • Inner Layer 1 : Power • Inner Layer 2 : Ground • Bottom Layer : Signal

-heavy_check_mark: Design Goals and Specific Areas for Feedback:

  1. Power Supply Stability: I'm particularly concerned about ensuring stable power to the SIM808 module. The power circuit includes components for USB/battery power switching. Any suggestions on component selection, layout, or decoupling for power stability?
  2. Power Consumption Optimization: I'm exploring power-saving features such as ESP32 deep sleep. Would love advice on component adjustments or layout techniques to reduce overall consumption.
  3. I2C Communication Reliability: This design involves multiple I2C devices connected to the ESP32-C3. Feedback on pull-up resistor values or tips for improving I2C communication stability would be very helpful.
  4. Antenna Placement and Routing: Since I have GSM and GPS antennas for the SIM808, I want to ensure optimal placement and minimal interference. Any best practices on antenna layout, ground plane isolation, or signal routing?

I've attached the schematic and PCB layout below. Looking forward to any insights you can provide to help make this design more robust and efficient.

Thanks in advance for your help! schematic enter image description here Top Layer and Bottom Layer

enter image description here

inner 1 and inner 2

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3d image enter image description here

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  • \$\begingroup\$ Hi do you have a 3d view of the board you could add? \$\endgroup\$ Commented Oct 27, 2024 at 17:58
  • \$\begingroup\$ yes i have , i added it . \$\endgroup\$ Commented Oct 27, 2024 at 18:08
  • \$\begingroup\$ Why don't you have any power/ground planes? \$\endgroup\$ Commented Oct 27, 2024 at 18:14
  • \$\begingroup\$ the power/ground planes exist in inner 1 and inner 2 layer \$\endgroup\$ Commented Oct 28, 2024 at 10:57

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You've got a great start and congratulations on getting your project going.

However, there's quite a lot you can do to improve it.

Diagram

Firstly, confused diagrams make confused circuits. It's really an important skill learning how to use your tools and make clear, logical, well-laid-out diagrams. With lots of labels and sensible flow, easy to read.

I notice you're using "physical layout" symbols for your chips and modules, ie, a symbol where the pins are in numerical order like on the physical package. Honestly, this is a terrible practice. If you can't find good library parts with logical layouts in the tool you're using, you need a better CAD tool.

You should definitely read the sticky post about good diagrams, I've marked a few areas on your diagram which jump out.

Titling and versioning seem pretty much absent from diagram and board.

  1. "Island Design" it's better to use wires for local connections and only use labelled signals for wide-distribution signals, so the eye is drawn along the signal flow.
  2. Up-is-up and ground is down. Ie, upwards is more positive. Always.
  3. Flow signals left to right
  4. Never allow text or symbols to overlap
  5. Never use four-way dot
  6. Completely uninformative MLX and APDS sections. I wonder what they are and what they do.
  7. Lay the sections out with some care. It can be good to put a box around each area, and label the box "CPU", "Temperature Sensor" whatever.
  8. Is there adequate decoupling? It certainly doesn't look like it.

enter image description here

Board layout

  1. Are you sure your need quad layer? Are you sure you need components on both sides?
  2. Inner layers? Are they full pours? Looks like no ground or power planes.
  3. Component layout looks very sparse and tracks look thin.
  4. Mounting holes definitely too close to the edge (don't forget extra space for washers, nuts)
  5. Rounded corners cost nothing (these days) and stop you cutting yourself
  6. Connector labelling is vital. Pin-1 marking is essential.
  7. Never let the silkscreen overlap so you can't read it.
  8. For debugging and testing, have you got a good place to put your oscilloscope ground clip? Good testpoints on the circuit?
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