If your first self-designed boards are noisy, reset randomly or behave differently on USB power vs lab supply, the problem is usually not your firmware. It’s your PCB layout.
Here are 8 practical rules you can apply immediately in KiCad, Altium, EasyEDA or any other CAD.
1. Keep critical signals short and direct
What to do: Route high‑speed and sensitive signals (clocks, oscillators, USB, SPI, ADC inputs) as short and as straight as you can.
Why it matters: Every millimeter of trace adds inductance, capacitance and antenna effect. That means more crosstalk, jitter, ringing and EMI.
Common mistake: Letting a clock or USB line wander across half the board “because there is space”. Then spending days wondering why the ADC is noisy or the serial link occasionally corrupts bytes.
2. Use a solid ground plane, not “ground spaghetti”
What to do: Dedicate at least one layer as a whenever possible. Route signals over that plane and avoid cutting it into islands.
