How to modify the frequency of the wireless module

Frequency is the most basic and core parameter of wireless modules. All wireless modules complete communication based on frequency (only the same frequency can complete communication). The frequencies in the market are 433MHz, 868MHz, 915MHz, etc. Those familiar with the wireless field know that each frequency band is actually a range of frequencies, such as 433MHz. Its frequency range is 413 ~ 453MHz, and 433MHz is the center point of this frequency. In the project, if all the wireless modules are placed on the same frequency, there will definitely be interference when communicating between them, so we usually stagger their communication frequency bands to avoid interference. 

How to modify the frequency of the wireless module?

The wireless modules of NiceRF are mainly divided into two categories. One is the front-end wireless module without MCU on board, and the center frequency point needs to be modified through code. The other is the uart wireless module with MCU on board, which can be independently controlled by our company. The PC software is developed to configure the parameters of the wireless module or send commands through the serial port to complete the modification.

1. Front-end wireless module

The following is an example of how our company's LoRa1262 wireless module can modify the frequency through the code (for reference only):

Function parameter: 32-bit unsigned positive number, which is the target frequency, for example, set the frequency to 433MHz. The parameter should be 433000000.

Return value: None.

void SX1262SetFrequency(u32 freq)

{

u8 CmdBuf[5];

CmdBuf[0]=SetRfFrequency;//Command to set frequency，SetRfFrequency=0x86;

 freq= (u32)(((double)freq)/((double)FREQ_STEP));//According to the specification of SX1262, calculate the corresponding register value.FREQ_STEP=/（2^25）,

  CmdBuf[1]= (unsigned char)( ( freq >> 24 ) & 0xFF );//High byte

  CmdBuf[2]= (unsigned char)( ( freq >> 16 ) & 0xFF );

  CmdBuf[3]= (unsigned char)( ( freq >> 8 ) & 0xFF );

  CmdBuf[4]= (unsigned char)( freq & 0xFF );

   SPIWriteCmd(5,CmdBuf);//Write

}

2. Uart wireless module

2.1 PC software modification

All of our uart wireless modules can have corresponding PC software. We can modify the central frequency point of the module through PC software. We only need to connect the module and PC through the serial port to complete the modification. It's very simple and convenient.

(LoRa610Pro PC configuration software)

2.2 Serial port assistant modification

The serial port assistant is modified by sending command symbols to the wireless module. Let's take the LoRa610Pro module as an example:

First, briefly introduce the parameter setting command format of the LoRa610Pro module: parameter setting command, with [parameter] of 33 bytes, and the sequence is as follows: Transceiver channel-working frequency band-air communication rate-transmit power-serial port baud rate-serial data Bit—Serial port stop bit—Serial port validation bit—NET ID—NODE ID-MESH—NODE—key type—16 bytes key configuration command: AA FA 03 XX XX XX XX XX XX …… XX XX XX XX XX XX XX XX XX Return command: "OK\r\n" or "ERROR\r\n".

（LoRa610Pro channel description）

(LoRa610Pro center frequency band description)

Suppose we set the working frequency of the LoRa610Pro module to 414.92MHz, then the configuration command is: AA FA 03 01 01 XX XX XX XX……XX XX XX XX XX XX XX XX XX.

For other XX specific parameters, please go to the official website of NiceRF LoRa610Pro uart wireless module to view the specifications.

Special Note:

In addition to the limitation of the chip, the working frequency of the wireless module is also important to the peripheral matching circuit of the antenna. Especially the center frequency is determined by the peripheral matching circuit. For example, LoRa1268 module of SX1268 chip, its working frequency is 433/470MHz, can it communicate if its working frequency exceeds the central frequency band of 433/470MHz (for example, set the working frequency band at 868MHz)? The answer is: of course. However, the peripheral matching circuit of the PCB board of each wireless module is made according to a specific frequency, and the antenna has the best operating frequency, so when the central operating frequency range of the wireless module is exceeded, the transmission distance will be greatly reduced. The distance of 100 meters, beyond the center frequency range, may not even be 10 meters. Therefore, users should set the center frequency range of each wireless module to ensure the best performance of the wireless module.

This is the end of today’s sharing of how to modify the frequency of the wireless module. If you have any other questions or suggestions, please feel free to contact NiceRF.