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PCB construction methods for embedded controllers

The most common method is of constructing embedded controller systems is a Printed Circuit Board (PCB). All electronics know that simple PCB is constructed of insulating material like epoxy impregnated glass cloth with a thin copper sheet(s) on one or both sides.

pcb

There are many conflicts about requirements on how to design interconnection patterns of PCB. But the main purpose for all is to make PCB reliable, effective and producible. If the circuit operates at a low speed, requirements are not as strict as for high-frequency devices where the parasitic effect cannot be ignored. Each PCB stray has its own resistance, capacitance, and inductance. These are the main effect that distorts the signals.

Ground and Power planes

This is not very actual for hobbyists as they usually develop single or double sideboards. But if the design uses a four-layer board, it is recommended to dedicate two layers for power and ground. So two PCB plains in parallel form a parasitic power supply decoupling capacitance, which reduces power supply noise. And, of course, these plains act as a shield for electromagnetic radiation.

Many circuit problems can be caused by improperly implemented ground. It may cause noise or erroneous operations to safety problems. For instance, because of excessive inductance there can “ground loops” appear. Or maybe because of bad insulation between different grounds like earth, analog, digital, the circuit wouldn’t work. Even a wrong grounding path may induce a voltage for another circuit. The solutions to these problems may vary. Sometimes it is enough to reduce current flow by using single-point ground and shielding.

EMC

The electromagnetic compatibility (EMC) problem arose when many electronic devices were used which radiate electromagnetic energy at frequencies close to communication frequencies. To solve the EMC problem first, you need to identify it. You need to eliminate or reduce it to defined limits by using shielding or simply removing/replacing the noise signal source.

ESD

Electrostatic Discharge (ESD) is also an important consideration in embedded systems. ESD also has the potential for failures and errors in operation. ESD usually occurs if there is an external electric field nearby. Then the impressed voltages may reach tens of thousands of Volts. This can happen if you walk in the humidity environment before touching the device and damaging it. The cure is only one- using grounding and shielding.

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