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Getting started with RFM95W, LoRa and ESP8266

In this blog post I will be introducing you to LoRa using the RFM95W module with an ESP8266, so let’s get started. I also wrote this article for the ESP32, read it here.

First, we should talk about what LoRa is and what it stands for. LoRa stands for Long Range and as the name suggests one of its main aspects is its considerable range. However, we need to make a distinction between LoRa and LoRaWAN. In this tutorial, I will be talking about LoRa. LoRaWAN adds another layer of authentification. Services like TheThingsNetwork (TTN) use LoRaWAN. However, LoRa is easier to use and understand for this tutorial.

Hardware used / Preparation

For this tutorial, I will be using an RFM95W module with an ESP8266. This is a bit tricky because there are some weird road bumps. The RFM95W is our LoRa communication chip. I’ve got my ESP from the german seller AZ-Delivery (I’m not affiliated with them in any way nor do I get any money from them for mentioning their name). My RFM95W comes from Amazon.

For this, I will assume that your Arduino IDE is set up to work with ESP8266s. If not here is a tutorial to do it.

Wiring

The wiring diagram

If you have a different ESP you can check the documentation supplied below for further details.

Now get started, for real

As a first step build up the setup shown above. Next, you need to install the LoRa Libary by Sandeep Mistry. More documentation is available here.

This code is actually the library’s example code modified to give a little more output.

Use the right frequencies for your region

Different regions use different frequencies for LoRa. Please check your local guidelines. Europe uses 868MHz (868E6). Update your LoRa.begin line! Here is a table by TTN.

#include <SPI.h>
#include <LoRa.h>

int counter = 0;
// - Pin configs -
#define ss 4    // D2
#define rst  5 // D1
#define dio0 -1

void setup() {
  Serial.begin(115200);
  while (!Serial);
  delay(1000);

  Serial.println("LoRa Sender");
  // Setup LoRa transceiver module
  LoRa.setPins(ss, rst, dio0);
  
  if (!LoRa.begin(868E6)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }else{
    Serial.println("Starting LoRa successful");
    }
  
}

// Sends a string every 5000ms (5 seconds)
void loop() {
  Serial.print("Sending packet: ");
  Serial.println(counter);

  // send packet
  LoRa.beginPacket();
  LoRa.print("hello ");
  LoRa.print(counter);
  LoRa.endPacket();

  counter++;

  delay(5000);
}

Information

I was unable to make the DIO0 work. This is why this sketch does not use it. Be aware!

I’ve had some issues using the code out-of-the-box. Some problems are due to the code lacking a lot of verbosity and some are due to user problems. The code above fixes one of the issues, verbosity. The other one is addressed below.

Tip

Please note that the library expects GPIO pins, not D pins. More information is available here.

After changing your frequencies and making sure that you use the right board, hit the upload button. After the upload is done open your serial console, select 115200 baud. Then you should see this output:

A arduino serial output window.
The serial output

And finally, your ESP is sending LoRa. Some of the items I need for receiving are stuck in shipping this has to wait for another day. However, below is a short paragraph for those who already own an SDR.

Does this even work? For people with SDRs

This paragraph is made for people who own SDRs (SoftwareDefinedRadio). For this, I’m using a VM running ParrotOS. This image comes preinstalled with SDR++. GNUradio and a bunch of extensions for GNUradio. These extensions also contain gr-lora, which I will be using here. Following this tutorial in the wiki, you should be able to set up your workspace to receive LoRa messages. Please also remember to use the right frequency. The results looks something like this:

With this setup, I was able to use a pretty good range, even though I only used a so-called random wire antenna. This also shows how some packets are missing some data. This shows why you should always use the hash numbers to verify that the received packet is healthy. I will be talking about hashes sometime in the future.

The result as seen in SDR++

I hope I could get you on your way into the interesting world of LoRa.

Willkommen

Willkommen in meinem neuen Blog! Hier soll es um Technik, Arduinos und andere Dinge gehen. Ich werde Projekte, Ideen und Tutorials veröffentlichen und hoffe, dass euch diese neuen Inhalte gefallen. Außerdem werde ich zu manchen meiner YouTube Videos Begleitartikel veröffentlichen. Ich würde mich über euer Feedback freuen.

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