1. The purpose of PCB design should be clear. For important signal lines, the length of wiring and processing ground loops should be very strict. For low-speed and unimportant signal lines, it can be placed on a slightly lower wiring priority. . Important parts include: division of power supply; length requirements of memory clock lines, control lines and data lines; wiring of high-speed differential lines, etc. In project A, a memory chip is used to realize DDR memory with a size of 1G. The wiring for this part is very critical. The topology distribution of control lines and address lines, and the length difference control of data lines and clock lines must be considered. In the process, according to the data sheet of the chip and the actual operating frequency, the specific wiring rules can be obtained. For example, the length of the data lines in the same group should not differ by more than several mils, and the length difference between each channel should not exceed how many mils. mil and so on. When these requirements are determined, the PCB designers can be clearly required to implement them. If all the important routing requirements in the design are clear, they can be converted into overall routing constraints, and the automatic routing tool software in CAD can be used to realize the PCB design. It is also a development trend in high-speed PCB design.
2. Inspection and debugging When preparing to debug a board, be sure to do a careful visual inspection first, check whether there are visible short circuits and pin tin failures during the soldering process, and check whether there are component models placed Errors, wrong placement of the first pin, missing assembly, etc., and then use a multimeter to measure the resistance of each power supply to ground to check whether there is a short circuit. This good habit can avoid damage to the board after rashly powering on. In the process of debugging, you must have a peaceful mind. It is very normal to encounter problems. What you need to do is to do more comparisons and analysis, and gradually eliminate possible causes. You must firmly believe that “everything can be solved” and “problems must be solved.” There is a reason for it”, so that the debugging will be successful in the end.
3. Some summary words Now from a technical point of view, every design can eventually be made, but the success of a project depends not only on the technical implementation, but also on the completion time, product quality, team Therefore, good teamwork, transparent and candid project communication, meticulous research and development arrangements, and abundant materials and personnel arrangements can ensure the success of a project. A good hardware engineer is actually a project manager. He/she needs to communicate with the outside world to obtain requirements for their own designs, and then summarize and analyze them into specific hardware implementations. It is also necessary to contact many chip and solution suppliers to select the appropriate solution. When the schematic diagram is completed, he/she has to organize colleagues to cooperate with review and inspection, and also work with CAD engineers to complete the PCB design. . At the same time, prepare the BOM list, start purchasing and preparing materials, and contact the processing manufacturer to complete the board placement. In the process of debugging, he/she should organize software engineers to solve key problems together, cooperate with test engineers to solve problems found in the test, and wait until the product is launched to the site. If there is a problem, it needs to be supported in time. Therefore, to be a hardware designer, you must exercise good communication skills, the ability to adjust to pressure, the ability to coordinate and make decisions when dealing with multiple affairs at the same time, and a good and peaceful attitude. There is also care and seriousness, because a small negligence in hardware design can often cause very large economic losses. For example, when a board was designed and the manufacturing documents were completed before, the misoperation caused the power layer and the ground layer to be connected. At the same time, after the PCB board was manufactured, it was directly mounted on the production line without inspection. It was only during the test that the short circuit problem was found, but the components were already soldered to the board, resulting in hundreds of thousands of losses. Therefore, careful and serious inspection, responsible testing, and unremitting learning and accumulation can make a hardware designer make continuous progress, and then make some achievements in the industry.
1. The purpose of PCB design should be clear. For important signal lines, the length of wiring and processing ground loops should be very strict. For low-speed and unimportant signal lines, it can be placed on a slightly lower wiring priority. . Important parts include: division of power supply; length requirements of memory clock lines, control lines and data lines; wiring of high-speed differential lines, etc. In project A, a memory chip is used to realize DDR memory with a size of 1G. The wiring for this part is very critical. The topology distribution of control lines and address lines, and the length difference control of data lines and clock lines must be considered. In the process, according to the data sheet of the chip and the actual operating frequency, the specific wiring rules can be obtained. For example, the length of the data lines in the same group should not differ by more than several mils, and the length difference between each channel should not exceed how many mils. mil and so on. When these requirements are determined, the PCB designers can be clearly required to implement them. If all the important routing requirements in the design are clear, they can be converted into overall routing constraints, and the automatic routing tool software in CAD can be used to realize the PCB design. It is also a development trend in high-speed PCB design.
2. Inspection and debugging When preparing to debug a board, be sure to do a careful visual inspection first, check whether there are visible short circuits and pin tin failures during the soldering process, and check whether there are component models placed Errors, wrong placement of the first pin, missing assembly, etc., and then use a multimeter to measure the resistance of each power supply to ground to check whether there is a short circuit. This good habit can avoid damage to the board after rashly powering on. In the process of debugging, you must have a peaceful mind. It is very normal to encounter problems. What you need to do is to do more comparisons and analysis, and gradually eliminate possible causes. You must firmly believe that “everything can be solved” and “problems must be solved.” There is a reason for it”, so that the debugging will be successful in the end.
3. Some summary words Now from a technical point of view, every design can eventually be made, but the success of a project depends not only on the technical implementation, but also on the completion time, product quality, team Therefore, good teamwork, transparent and candid project communication, meticulous research and development arrangements, and abundant materials and personnel arrangements can ensure the success of a project. A good hardware engineer is actually a project manager. He/she needs to communicate with the outside world to obtain requirements for their own designs, and then summarize and analyze them into specific hardware implementations. It is also necessary to contact many chip and solution suppliers to select the appropriate solution. When the schematic diagram is completed, he/she has to organize colleagues to cooperate with review and inspection, and also work with CAD engineers to complete the PCB design. . At the same time, prepare the BOM list, start purchasing and preparing materials, and contact the processing manufacturer to complete the board placement. In the process of debugging, he/she should organize software engineers to solve key problems together, cooperate with test engineers to solve problems found in the test, and wait until the product is launched to the site. If there is a problem, it needs to be supported in time. Therefore, to be a hardware designer, you must exercise good communication skills, the ability to adjust to pressure, the ability to coordinate and make decisions when dealing with multiple affairs at the same time, and a good and peaceful attitude. There is also care and seriousness, because a small negligence in hardware design can often cause very large economic losses. For example, when a board was designed and the manufacturing documents were completed before, the misoperation caused the power layer and the ground layer to be connected. At the same time, after the PCB board was manufactured, it was directly mounted on the production line without inspection. It was only during the test that the short circuit problem was found, but the components were already soldered to the board, resulting in hundreds of thousands of losses. Therefore, careful and serious inspection, responsible testing, and unremitting learning and accumulation can make a hardware designer make continuous progress, and then make some achievements in the industry.