PCB Tech - Precautions for PCB circuit board design of smart bracelet

Precautions for PCB circuit board design of smart bracelet

Smart bracelet, as a popular product form in the past two years, has attracted more and more people's attention. Although it cannot be accepted by all people, its production has indeed brought about some changes in the electronic product market. The editor of Yuwei Electronics will let you know about the PCB design precautions of the smart bracelet.

A smart bracelet usually consists of a radio frequency circuit unit, a clock circuit unit, a memory circuit unit, a sensor circuit unit, and a master MCU unit. The circuit PCB is usually concentrated in a small area for single-sided or double-sided patching. The circuit boards are mainly 4-layer circuit boards and 6-layer circuit boards.

Since so many functions are concentrated on a small PCB board, we need to pay extra attention to the layout and wiring of the bracelet. Now we summarize some precautions for reference.

First of all, the partition layout, pay attention to the wiring protection.

From the above PCB multilayer circuit board, it can be seen that each part of the circuit of the smart bracelet (marked with different color boxes) has a good partition: because the smart bracelet is a collection of digital circuit components, only in the circuit design By doing a good job of matching resistance and capacitance distribution, a circuit module with a certain function can be completed, 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, data communication and information transmission can be completed through the corresponding connection interface.

In the layout of circuit modules, on the one hand, it is necessary to pay attention to the shortest path between the clock circuit and the crystal oscillator circuit to reach the target control. On the other hand, pay attention to avoiding the data line when routing the clock to prevent interference from affecting the stability of the system.

When wiring, it is necessary to protect the key wiring, such as whether the clock generating circuit, crystal oscillator circuit, etc. are protected by copper coating, whether the ring ground protection is performed, etc., generally will be protected in the design, and the crystal oscillator part needs to be digged in copper. .

Secondly, handle the radio frequency circuit well.

The smart bracelet needs to be linked with the mobile phone when in use. Therefore, the radio frequency part is the key part. In this part of the design, special attention must be paid. Now the smart bracelets on the market are nothing more than wireless data transmission based on Bluetooth, so the focus is on the processing of Bluetooth radio frequency. If the smart bracelet is only used for data transmission and does not require the transmission of sound and music, then Bluetooth Low Energy is the best choice. In the design, the shape of the Bluetooth antenna, the antenna layout, and the material of the smart bracelet casing all affect the intelligence An important factor in the performance of the bracelet. In the smart bracelet PCB design process, an excellent RF antenna engineer is particularly important.

Again, do ESD protection.

In the previous article, I also wrote some technology and knowledge about circuit ESD. Today, it is important to talk about the importance of ESD to smart bracelet products. Different countries and regions have different standards for different products or the same product ESD requirements. In order to make the product pass the relevant test, the ESD protection design must be carried out during the design, and the ESD test must be carried out after the design is completed to ensure that the product passes the product. Electronic testing adapted to the local market.

Finally, reserve the system upgrade interface.

Whether it is convenient to upgrade the functions of a smart bracelet is of great significance to users or smart bracelet enthusiasts. If a product undergoes software upgrades at an appropriate time (maybe the early hardware design has some functions but the software has not kept up in order to catch up with the market, or it may be that some software bugs have been repaired), this indicates that the product is still non-stop In the development process, this is a good psychological compensation for users. There are usually two ways to upgrade the software of smart bracelets: through the USB interface and the method of wireless push. As for which method to use, it needs to be determined in the preliminary planning and software and hardware planning.