Mobile LoRa short message transmitter/receiver

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Need to send pre-defined short messages in uncovered wifi/4G/5G area? Check out my project!

 

Mobile LoRa short message transmitter/receiver

Things used in this project

 

Hardware components

HARDWARE LIST
1 DFRobot FireBeetle ESP32 IOT Microcontroller (Supports Wi-Fi & Bluetooth)
1 Pushbutton Switch, Momentary
1 Buzzer
1 Graphic OLED, 128 x 32 Pixels

Software apps and online services

 

Arduino IDE

Story

 

Introduction

 

I’ve always been fascinated by the fact that we can transmit data for a long distance between two devices.

The thing that is fantastic is that it can be done totally free or charge without the use of a mobile subscription.

These two devices allow to send and receive small messages using LoRa technology:

 #ESP32#RFM95#Battery#Antenna

#arduino #arduinoproject #esp32 #rfm95 #lora

VIDEO

How to change config

 

- In case you need to add other devices, you need to modify the "localAddress" variable and make it unique

- In case you need to address a specific device, you need to modify the "destination" variable and put the value of the device you want to message

- In case you want to message all devices, you need to put the value 255 in the "destination" variable.

- In case you want to add more messages, you need to modify the "messages.h" file and change the NUMBER_OF_STRING with a value equal to the number of messages you want to have as options. Then you need to add the string at the end of the "char arr" array.

Schematics

 

Mobile Two-Way short message device

projectImage

Code

Two-Way mobile short message device

Arduino

CODE
/*
  LoRaNow Messaging with ESP32

  This code send messages between Devices.
  
  created 19 06 2022
  by Carlo Stramaglia
*/

#include <SPI.h>              // include libraries
#include <LoRa.h>
#include <U8g2lib.h>
#include "OneButton.h"
#include "messages.h"

#ifdef U8X8_HAVE_HW_SPI
#include <SPI.h>
#endif
#ifdef U8X8_HAVE_HW_I2C
#include <Wire.h>
#endif

U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ SCL, /* data=*/ SDA, /* reset=*/ U8X8_PIN_NONE);

#define PIN_INPUT 15 // PIN for push button
#define PIN_BUZ 4 // PIN for buzzer
// current Buzzer state, staring with LOW (0)
int buzState = LOW;
OneButton button(PIN_INPUT, true);

int exitFlag = 0;
int stringNumber = -1;

const int csPin = 5;          // LoRa radio chip select
const int resetPin = 14;       // LoRa radio reset
const int irqPin = 2;         // change for your board; must be a hardware interrupt pin

String outgoing;              // outgoing message

byte msgCount = 0;            // count of outgoing messages
byte localAddress = 0xBA;     // address of this device
byte destination = 0xFF;      // destination to send to
long lastSendTime = 0;        // last send time
int interval = 2000;          // interval between sends



void setup() {
  Serial.begin(115200);                   // initialize serial
  u8g2.begin();

  // enable the buzzer
  pinMode(PIN_BUZ, OUTPUT); // sets the digital pin as output
  digitalWrite(PIN_BUZ, buzState); // sets the buzzer in mute

  // link the doubleclick function to be called on a doubleclick event.
  button.attachClick(Click);
  button.attachLongPressStart(longPressStart);
  
  // override the default CS, reset, and IRQ pins (optional)
  LoRa.setPins(csPin, resetPin, irqPin);// set CS, reset, IRQ pin

  if (!LoRa.begin(866E6)) {             // initialize ratio at 868 MHz
    Serial.println("LoRa init failed. Check your connections.");
    while (true);                       // if failed, do nothing
  }

  Serial.println("LoRa init succeeded.");
}

void loop() {

  delay(10);
  button.tick();
  // parse for a packet, and call onReceive with the result:
  onReceive(LoRa.parsePacket());
}

void sendMessage(String outgoing) {
  LoRa.beginPacket();                   // start packet
  LoRa.write(destination);              // add destination address
  LoRa.write(localAddress);             // add sender address
  LoRa.write(msgCount);                 // add message ID
  LoRa.write(outgoing.length());        // add payload length
  LoRa.print(outgoing);                 // add payload
  LoRa.endPacket();                     // finish packet and send it
  msgCount++;                           // increment message ID
}

void onReceive(int packetSize) {
  if (packetSize == 0) return;          // if there's no packet, return

  // read packet header bytes:
  int recipient = LoRa.read();          // recipient address
  byte sender = LoRa.read();            // sender address
  byte incomingMsgId = LoRa.read();     // incoming msg ID
  byte incomingLength = LoRa.read();    // incoming msg length

  String incoming = "";

  while (LoRa.available()) {
    incoming += (char)LoRa.read();
  }

  if (incomingLength != incoming.length()) {   // check length for error
    Serial.println("error: message length does not match length");
    return;                             // skip rest of function
  }



  // if the recipient isn't this device or broadcast,
  if (recipient != localAddress && recipient != 0xFF) {
    Serial.println("This message is not for me.");
    return;                             // skip rest of function
  }

  // if message is for this device, or broadcast, print details:
  Serial.println("Received from: 0x" + String(sender, HEX));
  Serial.println("Sent to: 0x" + String(recipient, HEX));
  Serial.println("Message ID: " + String(incomingMsgId));
  Serial.println("Message length: " + String(incomingLength));
  Serial.println("Message: " + incoming);
  Serial.println("RSSI: " + String(LoRa.packetRssi()));
  Serial.println("Snr: " + String(LoRa.packetSnr()));
  Serial.println();
  digitalWrite(PIN_BUZ, !buzState);
  Serial.println("Buzzer ON");
  delay (100);
  digitalWrite(PIN_BUZ, buzState);
  Serial.println("Buzzer OFF");
  sendDisplay(sender, incoming);
}

void sendDisplay(unsigned int nodeID, String messageLoRa) {
  char messageLocal[MAX_STRING_SIZE];
  u8g2.clearBuffer();          
  u8g2.setFont(u8g2_font_ncenB08_tr); 
  sprintf (messageLocal, "Message From: %d", nodeID);
  u8g2.drawStr(0,10, messageLocal);
  messageLoRa.toCharArray(messageLocal, MAX_STRING_SIZE);
  u8g2.drawStr(0,30, messageLocal); 
  u8g2.sendBuffer();          
  delay(1000);  
}


void Click()
{
  Serial.println("x1");
  stringNumber++;
  if (stringNumber > 3)
    stringNumber = 0;
  displayString (stringNumber+1, arr[stringNumber]);
  
  exitFlag = 0;

} // Click

void longPressStart()
{
  Serial.println("Long");
  displaySend (stringNumber+1, arr[stringNumber]);
  // Send data to the node
  //LoRaNow.clear();
  sendMessage(arr[stringNumber]);
  exitFlag = 1;
 
} // LongPressStart


void displayString (unsigned int stringNo, char* stringToDisplay) {
  char messageLocal[MAX_STRING_SIZE];
  u8g2.clearBuffer();          
  u8g2.setFont(u8g2_font_ncenB08_tr); 
  sprintf (messageLocal, "Destination: %d", destination);   
  u8g2.drawStr(0,10, messageLocal);
  sprintf (messageLocal, "Text selection: %d of %d", stringNo, NUMBER_OF_STRING); 
  u8g2.drawStr(0,20, messageLocal);
  u8g2.drawStr(0,30, stringToDisplay); 
  u8g2.sendBuffer();          
  delay(100);  
}

void displaySend (unsigned int stringNo, char* stringToDisplay) {
  char messageLocal[MAX_STRING_SIZE];
  u8g2.clearBuffer();          
  u8g2.setFont(u8g2_font_ncenB08_tr); 
  sprintf (messageLocal, "Destination: %d", destination);
  u8g2.drawStr(0,10, messageLocal);
  sprintf (messageLocal, "Sending Message: %d of %d", stringNo, NUMBER_OF_STRING);  
  u8g2.drawStr(0,20, messageLocal);
  u8g2.drawStr(0,30, stringToDisplay); 
  u8g2.sendBuffer();          
  delay(100);  
}

messages.h

Arduino

CODE
#define NUMBER_OF_STRING 4
#define MAX_STRING_SIZE 40

char arr[NUMBER_OF_STRING][MAX_STRING_SIZE] =
{ "Get on the phone!",
  "The music is too loud",
  "I'm ready to move",
  "See you at 10:00 AM"
};

The article was first published in hackster, July 8, 2022

cr: https://www.hackster.io/cstram/mobile-lora-short-message-transmitter-receiver-ce6136

author: cstram

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