Since so many functions are concentrated on a small PCB board, we need to pay extra attention to the layout and wiring of the hand ring, and now sum up some notes for reference.
First, partition layout, pay attention to line protection.
Can be seen from the above PCB circuit boards, intelligent bracelet all parts of the circuit (different color box) has good partitions: due to the intelligent hand ring is digital circuit components together, just be in the circuit design of form a complete set of resistance and capacitance distribution, can accomplish a certain function of the circuit module, which makes the circuit design more concise and easy to find.Although some sensor circuit units use analog circuit technology for data collection, once the module is designed as a module, then data communication and information transmission can be completed through the corresponding connection interface.
In the layout of the circuit module, on the one hand, the clock circuit and the crystal oscillator circuit should go through the shortest path to reach the target control; on the other hand, the data line should be avoided when the clock goes, so as to prevent interference from affecting the stability of the system.
When routing, key routing needs to be protected, such as whether the clock generating circuit, crystal oscillator circuit, etc., should be protected with copper, and whether it should be protected with ring ground. Generally, protection will be carried out in the design.
Second, handle the radio frequency circuit well.
The smart bracelet needs to interact with the mobile phone when used. Therefore, the radio frequency part is the key part. In this part of the design, special attention should be paid to it.Currently, the smart bracelet on the market is nothing but wireless data transmission based on bluetooth, so it focuses on the processing of bluetooth radio frequency.If the smart bracelet is only used for data transmission rather than voice and music transmission, then low-power bluetooth is the optimal choice. In the design, the shape of the bluetooth antenna, antenna layout, and the shell material of the smart bracelet are all important factors affecting the performance of the smart bracelet.In the design process of smart bracelet PCB, a good radio frequency antenna engineer is particularly important.
Third, protect the ESD.
In the previous article, I also wrote about some technologies and knowledge of circuit ESD. Today, I would like to talk about the importance of ESD for smart bracelet products.Different countries and regions have different standards for different products or the same product ESD requirements. In order to pass relevant tests, ESD protection design should be carried out in the design process, and ESD testing should be carried out after the design is completed to ensure that products can be tested electronically in the local market.