Getting started with LoRa + AT commands

I got my hands on REYAX Lora modules, and in this tutorial, we will configure these modules to communicate with each other. Lora platform is known for its long range as specified by the name LoRa (Long range radio). The normal communication distance is 8Km with rubber ducky antenna. Internet is not required in these trans-receiver modules. So, used to operate electric appliances in villages with this low-cost module.

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Reyax Lora:

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The RYLR998 transceiver module feature the LoRa long range modem that provides ultra-long range spread spectrum communication and high interference immunity whilst minimizing current consumption. This one supports UART protocol and has an inbuilt low power Nuvaton’s microcontroller. So, only few connections are needed to be done externally & can be operated on 3.3volts.Features:

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NUVOTON MCU & Semtech LoRa EngineExcellent blocking immunitySmart receiving power saving modeHigh sensitivityControl easily by AT commandsBuilt-in antenna

Components required:

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1) FTDI or CH340G programmer2) LORA modules3) Breadboard4) Jumper wires5) Battery(5v)6) USB cable

Connections with Lora:

This radio module has inbuilt nuvoton’s microcontroller, which is required to set up the connection using UART(RX-TX). But this need a external programmer board to convert USB data into Serial data.

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So here I am using FTDI232RL programmer chip, the connection is very simple as shown in the figure.First, set the correct COM port and then by choosing Arduino Nano or any other as microcontroller board open the Serial monitor. By default, the baud rate is 115200 and frequency is 865Mhz.

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Start With AT command to check the connection between Lora and programmer board, this will show a +OK message on the serial monitor.

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Configuration menu:

1. Use “AT+ADDRESS” to set ADDRESS. The ADDRESS is regard as the identification of transmitter or specified receiver.

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2. Use “AT+NETWORKID” to set the ID of LoRa® network. This is a Group function. Only by setting the same NETWORKID can the modules communicate with each other. If the ADDRESS of specified receiver is belonged to different group, it is not able to communicate with each other.3. Use” AT+BAND” to set the centre frequency of wireless band. The transmitter and the receiver are required to use the same frequency to communicate with each other.

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4. Use” AT+PARAMETER” to set the RF wireless parameters. The transmitter and the receiver are required to set the same parameters to communicate with each other.

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The parameters of which as follows:

[1] : The larger the SF is, the better the sensitivity is. But the transmission time will take longer.[2] : The smaller the bandwidth is, the better the sensitivity is. But the transmission time will take longer.[3] : The coding rate will be the fastest if setting it as 1.

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[4] : Preamble code. If the preamble code is bigger, it will result in the less opportunity of losing data. Generally preamble code can be set above 10 if under the permission of the transmission time. Recommend to set “AT + PARAMETER = 9, 7, 1, 12”

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5. Use “AT+SEND” to send data to the specified ADDRESS. Please use “LoRa Modem Calculator Tool” to calculate the transmission time. Due to the program used by the module, the payload part will increase more 8 bytes than the actual data length.

Application and Scope:

LoRa always plays with the range, good range radio modules can be used to do ON/OFF any machine, transfer data and communication without internet.

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