When working with wireless functions,developers will almost always choose wireless module.Sometimes, because they do not understand the various parameters of the wireless module, developers often spend a long time on setting the parameters. Infact, after following certain principles, the parameters of the wireless module become very simple. This article explains how to choose the right parameters.
First of all, it is clear what parameterswe can set artificially. Generally speaking, there are the followingparameters:
1.Frequency. The allowable frequency ofopen license-free frequencies varies from country to country. When setting thisparameter, it needs to be set within the allowed range according to therelevant local laws and regulations. When setting a specific frequency value,developers often set the value corresponding to the rate to be written to thecorresponding register according to the chip's specifications.
2.Rate. The rate determines the datatransmission speed. This parameter is easy to understand. However, for manychips, speed is not an existing parameter. A certain value of the rate oftendepends on other parameters, such as modulation mode, bandwidth, and spreading factor(lora-type chip or module). For example, taking SX1262 as an example, this is anew chip that supports lora modulation technology. NICERF Wireless has alsodeveloped front-end modules and data transmission modules based on this chip.In the chip reference manual of SX1262, there is no clear chapter on how to setthe rate. But as mentioned earlier, the speed of wireless chips is oftendetermined by multiple parameters, so is there a clear correspondence? Theanswer is yes. Take the ultra-low-receiving power consumption and high-powerwireless transceiver module LoRa1262F30 developed by NICERF wireless as an example. The settings of the speed andother parameters are shown in the following table:
From the table above, we can clearly see thecorrespondence between the speed and other parameters, which brings a lot ofconvenience to our development process. It should be noted here that the higherthe rate, not the better. With other conditions unchanged, the rate isinversely proportional to the chip's anti-interference performance andtransmission distance. Specifically: The higher the rate, the closer thetransmission distance of the wireless chip, the more error-prone thetransmission process (the ability to resist interference becomes lower). Duringthe development process, the developer should set these parameters reasonablyaccording to the actual requirements.
3.Bandwidth. Bandwidth refers to thefrequency width occupied by a signal. This parameter list, as mentionedearlier, is a parameter that affects the rate. This parameter should beselected according to the actual situation .
4.Modulation.Common modulation methods for wireless chips are lora, FSK, OOK, etc. Accordingto actual experience, the maximum data transmission rate of chips using fskmodulation is much faster than chips using lora modulation technology. Forexample, the SX1262 supports two debugging methods, lora and FSK. It is fasterwhen using FSK modulation, and generally only one method is used for actualdevelopment.
5.Frequency offset, this can be setaccording to the manufacturer's reference manual.
6.Leading length. The wireless chip judgeswhen there is a new data packet based on the content of the locked preamble. Ifthe preamble length is set too short, the receiver will frequently detect thewrong signal and wake up, and the power consumption will increase; while if thepreamble length is too long, the receiver needs to go through It takes longerto receive a packet. Therefore, the length of the data packet should be set toan appropriate value so that the chip can receive data quickly and accurately.Generally chip manufacturers will give a preamble user recommendation value.
7, spreading factor (only for chips withlora modulation) When spreading, each bit of data is multiplied by thespreading factor. For example, there is a 1 bit to be transmitted. When thespreading factor is 1, the data is transmitted during transmission. 1 isrepresented by a 1, when the spreading factor is 6 (there are 6 bits) 111111, this111111 represents a 1, so that each bit multiplied is represented by a 6-bitdata, which means that the total The amount of data has increased 6 times.
In this way, transmission after spreadingcan reduce the bit error rate, which is the signal-to-noise ratio, but underthe same data volume, the actual data that can be transmitted is reduced.Therefore, the larger the spreading factor, the greater the data rate (bitrate) of the transmitted data The smaller.
The above is a summary of the wirelessparameter settings. After the above introduction, I believe that everyone has aclear understanding of the parameter settings of wireless communication. Hopethis article can help everyone.