1, at least have a basic understanding of the wiring of power supply in printed circuit board, and know what consequences bad layout and wiring will have on the quality of power supply. Even if you have never designed the wiring of the circuit board yourself, you should be able to debug the possible problems caused by the chaotic layout of the printed circuit board. HowardJohnson's "High-speed Digital Design-A Handbook of Dark Magic" is very helpful for learning this knowledge.
2. Similarly, you should have a basic understanding of how the wiring of the printed circuit board affects the signal propagation.
3. Be able to read the circuit diagram.
4. Understand the various types of IO configurations of digital components such as microcontroller MCU, such as Opencollector(OC), open drain (OD), Push _ Pull output (Totempole output), whether there are protection diodes, etc. In particular, it is necessary to understand the problems of level conversion (the current system often has mixed IO voltage) and driving different loads. For example, you want to drive an inductive load similar to a relay, but you didn't pay attention to the inductive characteristics of the load when designing the circuit. When the relay is opened or closed, all kinds of strange phenomena appear.
5. Mastering simple skills to reduce the ESD sensitivity of the system, such as choosing a proper grounding location, Beijing Computer Training suggests correctly placing the discharge diode, series resistor and grounding capacitor.
6. Learning to use SPICE circuit simulation software is helpful, but not absolutely necessary.
7, master the practical skills of hardware debugging.