/*********

Rui Santos

Complete project details at https://RandomNerdTutorials.com/ttgo-lora32-sx1276-arduino-ide/

ttgoOLED_TX.ino LOCAL with Pi send single letter commands to get a one off response WIFI from Pi

/Users/graham/Dropbox/SystemsinUse/46_office_lora/lora_esp32/ttgoOLED_TX_command_from_office_WIFI/ttgoOLED_TX_command_from_office_WIFI.ino

NB! corrected by GPT 21/9/25 update 26/11/25 - OK - 27/11/25 OK

*********/

#include <WiFi.h>

#include <WebServer.h>

#include <SPI.h>

#include <LoRa.h>

#include <Wire.h>

#include <Adafruit_GFX.h>

#include <Adafruit_SSD1306.h>

// Wi-Fi credentials

const char* ssid = "deco";

const char* password = "uu8diode";

String reply = "";

WebServer server(80);

String receivedData = "";

// LoRa configuration

#define SCK 18

#define MISO 19

#define MOSI 23

#define SS 5

#define RST 14

#define DIO0 2

#define BAND 868E6

#define OLED_SDA 4

#define OLED_SCL 15

#define OLED_RST 16

#define SCREEN_WIDTH 128

#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RST);

void setup() {

Serial.begin(115200);

// OLED reset

pinMode(OLED_RST, OUTPUT);

digitalWrite(OLED_RST, LOW);

delay(20);

digitalWrite(OLED_RST, HIGH);

Wire.begin(OLED_SDA, OLED_SCL);

display.begin(SSD1306_SWITCHCAPVCC, 0x3C, false, false);

display.clearDisplay();

display.setTextColor(WHITE);

display.setTextSize(1);

display.setCursor(0, 0);

display.println("Wi-Fi + LoRa Node");

display.display();

IPAddress staticIP(192, 168, 1, 123); // ESP32 static IP

IPAddress gateway(192, 168, 1, 1); // Router IP

IPAddress subnet(255, 255, 255, 0); // Subnet mask

IPAddress primaryDNS(192, 168, 1, 1); // DNS (often same as router)

IPAddress secondaryDNS(8, 8, 8, 8); // Optional (Google DNS)

WiFi.mode(WIFI_STA); // Make sure we are in Station mode only

// Configure static IP – check for failure

if (!WiFi.config(staticIP, gateway, subnet, primaryDNS, secondaryDNS)) {

Serial.println("STA Failed to configure");

}

WiFi.begin(ssid, password);

display.setCursor(0, 10);

display.print("Connecting Wi-Fi...");

display.display();

String reply = "";

while (WiFi.status() != WL_CONNECTED) {

delay(500);

Serial.print(".");

}

Serial.println();

Serial.print("Connected. IP: ");

Serial.println(WiFi.localIP());

display.setCursor(0, 20);

display.println("Connected!");

display.display();

SPI.begin(SCK, MISO, MOSI, SS);

LoRa.setPins(SS, RST, DIO0);

if (!LoRa.begin(BAND)) {

Serial.println("LoRa init failed!");

while (true) { delay(1000); }

}

// --- NOW set parameters, after begin() ---

LoRa.setSpreadingFactor(9); // match Heltec

LoRa.setSignalBandwidth(125E3);

LoRa.setCodingRate4(5);

LoRa.setTxPower(17);

LoRa.setPreambleLength(8);

LoRa.setSyncWord(0x34);

// Keep CRC off, to match your Heltec's radio.setCRC(0)

LoRa.disableCrc(); // explicit, just to be sure

LoRa.disableInvertIQ(); // explicit, normal mode

// HTTP handler

server.on("/command", HTTP_POST, []() {

if (!server.hasArg("plain")) {

server.send(400, "text/plain", "Missing body");

return;

}

String command = server.arg("plain");

Serial.print("ESP32 IP Address: ");

Serial.println(WiFi.localIP()); // Print the ESP32 IP address to Serial Monitor

Serial.println("Received command: " + command); //WiFi command

display.clearDisplay();

display.setCursor(0, 0);

display.print("Wi-Fi cmd: ");

display.println(command);

display.display();

// Send command via LoRa

LoRa.beginPacket();

LoRa.print(command);

LoRa.endPacket();

// --- Wait for reply from slave ---

String reply = "";

int rssi = 0;

float snr = 0;

unsigned long start = millis();

while (millis() - start < 5000) { // wait up to 5 seconds

int packetSize = LoRa.parsePacket();

if (packetSize) {

reply = LoRa.readString();

// Get LoRa signal stats for this packet

rssi = LoRa.packetRssi(); // signal strength in dBm

snr = LoRa.packetSnr(); // signal-to-noise in dB

break;

}

delay(10); // small yield to avoid watchdog reset

}

if (reply == "") {

reply = "NoData";

}

// --- Serial output ---

Serial.println("Reply: " + reply);

Serial.print("LoRa RSSI: ");

Serial.print(rssi);

Serial.println(" dBm");

Serial.print("LoRa SNR: ");

Serial.print(snr);

Serial.println(" dB");

// --- HTTP reply to Pi ---

server.send(200, "text/plain", reply);

// --- OLED output ---

display.setCursor(0, 10);

display.println(WiFi.localIP());

display.setCursor(0, 20);

display.println(reply);

display.setCursor(0, 40);

display.print("RSSI: ");

display.print(rssi);

display.print(" dBm");

display.setCursor(0, 50);

display.print("SNR: ");

display.print(snr, 1);

display.print(" dB");

display.display();

});

server.begin();

Serial.println("HTTP server started");

}

void loop() {

server.handleClient();

}