PCB Design Study Notes

Considerations for PCB Design Goals

1. Functionality (power management, signal processing)
2. Hardware Compatibility (whether interfaces are widely used and easily accessible, whether they are compatible with existing circuit boards, considering the official electrical component interfaces of Robomaster)
3. Mechanical Structure Compatibility (considering mechanical mounting positions, standardizing screw sizes and hole positions, considering large interfaces that require screw fastening)
4. Hardware Reusability, multifunctionality (achieving other redundant functions, the same board for different purposes, can change functions through flying leads or non-soldered components)

PCB Design Metrics

1. Stability (power decoupling, signal integrity, good heat dissipation, reliable interfaces)
2. Reasonable Component Selection (actual usage far below limit specifications, component packaging easy for manual soldering, mature reference designs, low cost)
3. Layout Reasonableness (shortest routing, minimal board area, easy soldering)
4. Protection (reverse polarity protection, overcurrent protection, electrostatic protection, soft start)

PCB Design Specifications

1. First layout fixed component positions (to prevent accidental errors, components can be locked) and then connect the wires
2. Layout: consider the importance of components (high-frequency or MCU units should be positioned close), whether to reserve other space (for mechanical processing holes, heat dissipation or interface connections, installation of pin headers requires multiples of 100 mil), difficulty of component soldering (surface mount components side by side are easier to solder)
3. Routing: based on the signal direction in the board, connect in the order of ground lines, high-frequency lines, and power lines, other signal lines follow; consider thickening power ground and power lines (quantitative specifications), keep signal ground lines as short as possible and minimize vias; high-frequency lines (such as connections between crystal oscillators and MCUs) should be as short as possible and kept away from other lines (or surrounded by a grounding copper area around high-frequency components)
4. For multilayer boards, avoid adjacent parallel high-frequency lines between layers to prevent cross-layer crosstalk
5. No signal or power lines should run beneath high-frequency components (such as crystal oscillators) to prevent interference
6. Signal lines and power lines should be as close as possible to return lines (power return lines are ground lines) to reduce loop inductance and cancel some self-inductance
7. All signal lines should run in as straight a line as possible, avoiding right angles or near right angles, and should also be kept short