We have learned a lot about the components but still can’t design the circuit we want. It is a problem that plagues many people. In the end, what we lack is not the theoretical knowledge but the circuit design ideas and the actual experience. .
When designing a hardware circuit, in addition to mastering the hardware design basis, various design software, tool operation skills, etc., it is also necessary to develop a good hardware circuit design idea, which can help you go and finish it. How to cultivate the design idea of the hardware circuit, the following is the basic flow of the design for everyone.
Circuit design ideas
1) The overall idea. When designing hardware circuits, the big framework and architecture should be clear, but it is not easy to do this. Some big frameworks may have already designed. You just implement the ideas concretely; but some have to design their own frameworks, then you have to figure out what functions to implement, and then find out whether you can achieve the same or similar functions. The reference circuit board (to know how to make the best use of the results of others, the more experienced engineers will understand the results of others).
2) Understand the circuit. If you find a reference design, congratulations, you can save a lot of time (including pre-design and post-debugging). Copy now? NO, you need to understand it first. On the one hand it can improve our circuit understanding ability, and can avoid errors in the design.
3)Didn’t find the reference design? It’s ok. First determine the large IC chip, and then look for the datasheet, see if its key parameters meet their own requirements, which are the key parameters that they need, and whether they can understand these key parameters. These are the embodiment of the capabilities of hardware engineers, which also requires long-term accumulates.
4) The hardware circuit design is mainly three parts, schematic, pcb, bill of materials (BOM) table. Schematic design is to convert the previous ideas into circuit schematics. It is very similar to the circuit diagram in our textbook. Pcb involves the actual circuit board, which is based on the schematic diagram converted from the netlist (the netlist is the bridge between the communication schematic and the pcb), and the specific component package is placed (layout) on the circuit board. Then connect its electrical signal (wiring) according to the flying wire (also called pre-wire). After completing the PCB layout and routing, which components should be used, we will use the BOM.
5) Assemble the pcb and prepare the bom table, which can be directly exported from the schematic. However, it should be noted that in the schematic diagram, which parts of the components should be on and which components should not be on, it is necessary to have a clear understanding. For small batches or research boards, it is also convenient to use excel to manage it yourself (large companies often need professional software to manage). For the novice, the first version is not recommended to be directly handed over to the assembly plant or the welding factory to weld all the bom materials, which is not convenient for troubleshooting. The best way is to prepare the components yourself according to the bom table. After the board comes, step by step on the components and debug.
6) Problems with debugging. When preparing to debug a board, be sure to carefully check the visual inspection to see if there are visible short circuits and pin-stitching problems during the soldering process. Check if there are any component types placed incorrectly. Then use a multimeter to measure the resistance of each power supply to the ground to check for short circuits. This good habit can avoid damaging the board after powering up. In the process of debugging, we must have a peace of mind. It is very normal to meet the problem. What we need to do is to do more comparison and analysis, and gradually eliminate possible causes.