LoRa long-range communication system, similar to WIFI but working over very long distances (up to 10km). Unlike regular wifi, LoRa is designed to send only very small amounts of data, and pretty slowly.
Hardware
The Arduino MKR WAN 1310 is a board that combines the functionality of the MKR Zero and LoRa / LoRaWANTM connectivity. There are also modules that allow LoRa communication for almost any device, and several other Arduino based devices with inbuilt LoRa functionality.
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Compatible Antena
Jumper wires
Breadboard
A sensor
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Getting started with the MKR WAN 1310
For this experiment, we need need to LoRa devices. We need to have a compatible antenna connected to both our devices.
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The sender code sends a simple message w, with a delay of 5 seconds. Make sure you change the contents of myData.
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#include <SPI.h>
#include <LoRa.h>
int counter = 0;
String myData = "my name";
void setup() {
Serial.begin(9600);// wait until serial has started
Serial.println("LoRa Sender");
if (!LoRa.begin(868E6)) {
Serial.println("Starting LoRa failed!");
while (1);
}
delay(1000);
pinMode(LED_BUILTIN, OUTPUT);
}
void loop() {
Serial.print("Sending packet: ");
Serial.println(counter);
// send packet
LoRa.beginPacket();
LoRa.print(myData);
LoRa.print(" name");
LoRa.endPacket();
counter++;
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(4000);
} |
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#include <SPI.h>
#include <LoRa.h>
String contents = "";
void setup() {
Serial.begin(9600);
while (!Serial); // wait until serial has started
Serial.println("LoRa Receiver");
if (!LoRa.begin(868E6)) {
Serial.println("Starting LoRa failed!");
while (1);
}
}
void loop() {
// try to parse packet
int packetSize = LoRa.parsePacket();
if (packetSize) {
// received a packet
Serial.print("Received packet '");
// read packet
while (LoRa.available()) {
contents += (char)LoRa.read();
}
Serial.println(contents);
// print RSSI of packet
Serial.print("' with RSSI ");
Serial.println(LoRa.packetRssi());
contents = "";
}
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Advanced example MKR WAN 1310
In the previous example, you might have noticed a potential problem. The receiving device is getting LorRa messages from anyone sending data on that frequency. Furthermore, anyone can listen in to the data being sent. This could be resolved with some encryption, but that goes beyond the scope of this tutorial.
We are going to solve the problem by simply sending an ID with our packet, then checking it at the receiving end and discarding any other messages.
We are using the Serial port extensively here to see the workings of our code, which is very slow for the arduino. It would be wise to remove most of this communication before using the example in the real world.
Sender Code with an Analog Sensor.
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#include <SPI.h>
#include <LoRa.h>
int counter = 0;
String myUniqueId = "asdfw1";
void setup() {
Serial.begin(9600);
Serial.println("LoRa Sender");
if (!LoRa.begin(868E6)) {
Serial.println("Starting LoRa failed!");
while(1);
}
delay(1000);
pinMode(LED_BUILTIN, OUTPUT);
}
void loop() {
int sensorValue = analogRead(A0);
Serial.print("Sending packet: ");
Serial.println(counter);
// send packet
LoRa.beginPacket();
LoRa.print(sensorValue);
LoRa.print(",");
LoRa.print(myUniqueId);
LoRa.endPacket();
counter++;
digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level)
delay(1000); // wait for a second
digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW
delay(4000);
} |
Receiver Code
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#include <SPI.h> #include <LoRa.h> String contents = ""; String myUniqueId = "asdfw1"; void setup() { Serial.begin(9600); while (!Serial); Serial.println("LoRa Receiver"); if (!LoRa.begin(868E6)) { Serial.println("Starting LoRa failed!"); while (1); } pinMode(LED_BUILTIN, OUTPUT); } void loop() { // try to parse packet int packetSize = LoRa.parsePacket(); if (packetSize) { // received a packet Serial.print("Received packet '"); // read packet while (LoRa.available()) { contents += (char)LoRa.read(); } Serial.println(contents); // print RSSI of packet Serial.print("' with RSSI "); Serial.println(LoRa.packetRssi()); int commaIndex = contents.indexOf(','); String data = contents.substring(0, commaIndex); String ID = contents.substring(commaIndex + 1); if (data && ID) { Serial.println("Recieved Matching format"); if (ID.equals(myUniqueId)) { Serial.println("ID matches!"); digitalWrite(LED_BUILTIN, HIGH); Serial.print("data: "); Serial.println(data); } else { Serial.print(myUniqueId); Serial.print(" does not match "); Serial.println(ID); digitalWrite(LED_BUILTIN, LOW); } } contents = ""; } } |