The introduction of sx1262 module

NiceRF: The introduction of sx1262 module

Sx1262 module is a new generation of chips developed by Semtech, which is suitable for long-distance wireless communication. One of the characteristics of the wireless module is that the current of its receiving state is only 4.2mA. The chip also supports LoRa modulation forlpwan and (G)FSK modulation for traditional use. The maximum output power of the chip can reach + 22dBm, and it supports 433/490/868/915MHz. It is a popular chip in the market.

The main applications of the chip are as follows:

• Intelligent instrument
• Supply chain and logistics
• Building automation
• Agricultural sensors
• Smart city
• Retail store sensors
• Asset tracking
• Streetlamp
• Parking sensor
• Environmental sensors
• Healthcare
• Safety and security sensors
• Remote control applications

The following is a brief introduction to the process of using this chip.

This paper describes the process of using LoRa mode with chips.

First, we should reset the chip. According to the specification of the chip, to set the chip, first make the chip in standby mode. Then use the command SetPacketType() to select the packet type. There are two options: LoRa and FSK. The operating frequency should then be beset. Then set the power. These are parameters related to the RF part.

After that, the parameters related to FIFO are set, such as the base address of the parameter buffer, the parameters of the packet, such as the length of the preamble, the length of the packet, the timeout time, etc., which should be set according to the actual situation.

The chip has a busy pin to indicate its internal working state and 3 DIO pins to inform the main controller of new events. When the chip is in busy state, the busy pin will turn to high level. At this time, the main controller should not write new commands, but wait for the busy pin to turn to low level. The example procedure is as follows:

voidcheck_busy(void)

{

    uint8_t i = 0;

    while (RADIO_BusyPin())

    {

       //nop();

    }

}

The function on each DIO pin can be set independently. Users can also map interrupt signals to different DIO pins. In addition, DIO2 and DIO3 have a second function. Among them, dio2 can be used to control the antenna switch, and DIO3 can be used as the switch of TCXO crystal oscillator. Using these two pins can save the pins of external MCU. This brings great convenience to the development process. The following is the reference procedure for setting up DIO:

voidSX1262SetDioIrqParams(uint16_t   INT,uint16_t   dio1, uint16_t   dio2, uint16_t   dio3)

{

    uint8_t CmdBuf[9];

    CmdBuf[0] = SetDioIrqParams;

    CmdBuf[1] = INT >> 8;

    CmdBuf[2] = (uint8_t  )INT;

    CmdBuf[3] = dio1 >> 8;

    CmdBuf[4] = (uint8_t  )dio1;

    CmdBuf[5] = dio2 >> 8;

    CmdBuf[6] = (uint8_t  )dio2;

    CmdBuf[7] = dio3;

    CmdBuf[8] = (uint8_t  )dio3;

    SPIWriteCmd(9, CmdBuf);

}

Set DIO2 asantenna control switch:

voidSX1262SetAnt(void)

{

    uint8_t CmdBuf[2];

    CmdBuf[0] = SetDIO2AsRfSwitchCtrl;

    CmdBuf[1] = 0x01;

    SPIWriteCmd(2, CmdBuf);

}

Set DIO3 to TCXOcontrol switch:

void SX1262SetTCXO_Ctrl(void)

{

    uint8_t  CmdBuf[5];

    CmdBuf[0] = SetDIO3AsTcxoCtrl;

    CmdBuf[1] = DIO3_1_8V;

    CmdBuf[2] = 0;

    CmdBuf[3] = 0;

    CmdBuf[4] = 255;

    SPIWriteCmd(5, CmdBuf);

}

In addition, it should be noted that commands should be initiated in the correct order. Most of the commands can be sent in any order except for the radio configuration commands which will set the radio in the proper operating mode. Indeed, it is mandatory to set the radio protocol using the command SetPacketType(...) as a first step before issuing any other radio configuration commands. In a second step, the user should define the modulation parameter according to the chosen protocol with the command SetModulationParams(...). Finally, the user should then select the packet format with the command SetPacketParams(...).

Based on the sx1262 chip, NiceRF has developed a LoRa1262 front-end LoRa module. This module uses a TCXO crystal oscillator and has excellent performance, stability and reliability.

Hope this article is helpful to you.