Sending data over LoRa with Heltec ESP32 WifiKit. Having two ESp32 boards, the first test that come in mind is to send some packets!

Remember to connect the antenna to the board, as the producer reccomends, to avoid damage on the SX127x chip.

Make sure that you have set the ESP32 board in Arduino IDE. Look on internet or this article.

Next step, install heltec, LoRa (from Sandeep Mistry) and SSD1306 (from Daniel Eichhorn) display libraries:

The program for testing is sourced from alictronix.

Sender program

//https://www.alictronix.com/archives/860
#include <SPI.h>
#include <LoRa.h>
#include "SSD1306.h"
#include<Arduino.h>
 
//OLED pins to ESP32 GPIOs via this connecthin:
//OLED_SDA -- GPIO4
//OLED_SCL -- GPIO15
//OLED_RST -- GPIO16
 
SSD1306  display(0x3c, 4, 15);
 
// WIFI_LoRa_32 ports
// GPIO5  -- SX1278's SCK
// GPIO19 -- SX1278's MISO
// GPIO27 -- SX1278's MOSI
// GPIO18 -- SX1278's CS
// GPIO14 -- SX1278's RESET
// GPIO26 -- SX1278's IRQ(Interrupt Request)
 
#define SS      18
#define RST     14
#define DI0     26
#define BAND    433E6  //915E6 
 
int counter = 0;
 
void setup() {
  pinMode(25,OUTPUT); //Send success, LED will bright 1 second
  pinMode(16,OUTPUT);
  digitalWrite(16, LOW);    // set GPIO16 low to reset OLED
  delay(50); 
  digitalWrite(16, HIGH);
   
  Serial.begin(115200);
  while (!Serial); //If just the the basic function, must connect to a computer
  // Initialising the UI will init the display too.
  display.init();
  display.flipScreenVertically();
  display.setFont(ArialMT_Plain_10);
  display.setTextAlignment(TEXT_ALIGN_LEFT);
  display.drawString(5,5,"LoRa Sender");
  display.display();
   
  SPI.begin(5,19,27,18);
  LoRa.setPins(SS,RST,DI0);
  Serial.println("LoRa Sender");
  if (!LoRa.begin(BAND)) {
    Serial.println("Starting LoRa failed!");
    while (1);
  }
  Serial.println("LoRa Initial OK!");
  display.drawString(5,20,"LoRa Initializing OK!");
  display.display();
  delay(2000);
}
void loop() {
  Serial.print("Sending packet: ");
  Serial.println(counter);
  display.clear();
  display.setFont(ArialMT_Plain_16);
  display.drawString(3, 5, "Sending packet ");
  display.drawString(50, 30, String(counter));
  display.display();
  // send packet
  LoRa.beginPacket();
  LoRa.print("Hello..");
  LoRa.print(counter);
  LoRa.endPacket();
  counter++;
  digitalWrite(25, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(25, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
  delay(3000);
}

Receiver program

#include <SPI.h>
#include <LoRa.h>
#include "SSD1306.h"
 
SSD1306  display(0x3c, 4, 15);
 
//OLED pins to ESP32 GPIOs via this connection:
//OLED_SDA -- GPIO4
//OLED_SCL -- GPIO15
//OLED_RST -- GPIO16
// WIFI_LoRa_32 ports
// GPIO5  -- SX1278's SCK
// GPIO19 -- SX1278's MISO
// GPIO27 -- SX1278's MOSI
// GPIO18 -- SX1278's CS
// GPIO14 -- SX1278's RESET
// GPIO26 -- SX1278's IRQ(Interrupt Request)
 
#define SS      18
#define RST     14
#define DI0     26
#define BAND    433E6
 
void setup() {
  pinMode(16,OUTPUT);
  digitalWrite(16, LOW);    // set GPIO16 low to reset OLED
  delay(50); 
  digitalWrite(16, HIGH);
  display.init();
  display.flipScreenVertically();
  display.setFont(ArialMT_Plain_10);
  display.setTextAlignment(TEXT_ALIGN_LEFT);
   
  Serial.begin(115200);
  while (!Serial); //if just the the basic function, must connect to a computer
  delay(1000);
  Serial.println("LoRa Receiver"); 
  display.drawString(5,5,"LoRa Receiver"); 
  display.display();
  SPI.begin(5,19,27,18);
  LoRa.setPins(SS,RST,DI0);
   
  if (!LoRa.begin(BAND)) {
    display.drawString(5,25,"Starting LoRa failed!");
    while (1);
  }
  Serial.println("LoRa Initial OK!");
  display.drawString(5,25,"LoRa Initializing OK!");
  display.display();
}
void loop() {
  // try to parse packet
  int packetSize = LoRa.parsePacket();
  if (packetSize) {
    // received a packets
    Serial.print("Received packet. ");
    display.clear();
    display.setFont(ArialMT_Plain_16);
    display.drawString(3, 0, "Received packet ");
    display.display();
    // read packet
    while (LoRa.available()) {
    String data = LoRa.readString();
    Serial.print(data);
    display.drawString(20,22, data);
    display.display();
    }
    // print RSSI of packet
    Serial.print(" with RSSI ");
    Serial.println(LoRa.packetRssi());
    display.drawString(20, 45, "RSSI:  ");
    display.drawString(70, 45, (String)LoRa.packetRssi());
    display.display();
  }
}

Upload the code to each board, and then wait for results:

 

Happy blinking!

 


2PCS 868MHz-915MHz SX1276 ESP32 LoRa 0.96 Inch Blue OLED Display Bluetooth WIFI Lora Kit 32 V2 Development Board for Arduino

Heltec Wireless stick upgrade esp32 lora/wifi lora Development Board with 0.49inch oled display 433HMZ/868MHZ/915MHZ

ESP32 lora send/receive packet test
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3 thoughts on “ESP32 lora send/receive packet test

  • January 19, 2020 at 23:05
    Permalink

    Hello. thanks for all the information available. I have a question. is there a function in the library that allows us to confirm that the message has been delivered? Or it is up to us to implement a callback confirming the integrity of the message. Or any other technique that allows the recipient to confirm that every message has been received. So let the sender know that everything is ok. does this have to be implemented by us?

    Reply
    • September 24, 2020 at 05:29
      Permalink

      this messages are not like in TCP protocol, more likely as UDP: the packet is sent without waiting for a confirmation

      Reply
  • August 3, 2020 at 20:04
    Permalink

    An excellent article, I read many articles on this topic and tried various sketches, it does not work, I thought that the module was out of order and then I came across your article. Thank!

    Reply

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