Sending sensor data to Thingspeak using SIM800L v2

[ardakias]

Hey,

I want to send temperature data DS18B20 using SIM800L v2 to ThingSpeak from an Arduino Uno R4 wifi.

I found this code from this tutorial, which I adjusted (using chatgpt) just for my sensor, but when I expect "Response from ThingSpeak:", I get just blank text.

I am new in Arduino, so I have been trying troubleshooting it watching other similar guides, but I cannot get it work.

Here is the latest code:

#include <OneWire.h>
#include <DallasTemperature.h>
#include <SoftwareSerial.h>

// Pin configuration
#define DS18B20_PIN 2       // DS18B20 data pin
#define SIM800_TX 10        // SIM800L TXD pin
#define SIM800_RX 11        // SIM800L RXD pin

// SoftwareSerial for SIM800L
SoftwareSerial SIM800(SIM800_TX, SIM800_RX);

// ThingSpeak settings
const char* APN = "apn";                       // APN for your SIM card
const char* USERNAME = "";             // Username for your APN (if required)
const char* PASSWORD = "";             // Password for your APN (if required)
const char* THINGSPEAK_API_KEY = "APIKEY";    // ThingSpeak API Key
const char* THINGSPEAK_HOST = "SERVER"; // ThingSpeak server hostname

OneWire oneWire(DS18B20_PIN);
DallasTemperature sensors(&oneWire);

void setup() {
  Serial.begin(9600);
  SIM800.begin(9600);

  sensors.begin();
  delay(1000);

  Serial.println("Initializing SIM800L...");
  SIM800.println("AT");
  delay(1000);
  SIM800.println("AT+CREG?");
  delay(1000);
  SIM800.println("AT+CGATT?");
  delay(1000);
}

void loop() {
  float temperature = readTemperature();

  if (!isnan(temperature)) {
    if (!isGPRSConnected()) {
      connectGPRS();
    }

    sendToThingSpeak(temperature);
    disconnectGPRS();
  } else {
    Serial.println("Error reading temperature");
  }

  delay(10000); // Wait for 10 seconds before the next update
}

float readTemperature() {
  sensors.requestTemperatures();
  return sensors.getTempCByIndex(0);
}

boolean isGPRSConnected() {
  SIM800.println("AT+CGATT?");
  String response = readSerial();
  return response.indexOf("+CGATT: 1") != -1;
}

void connectGPRS() {
  SIM800.println("AT+CGATT=1");
  delay(1000);
  SIM800.println("AT+SAPBR=3,1,\"CONTYPE\",\"GPRS\"");
  delay(1000);
  SIM800.println("AT+SAPBR=3,1,\"APN\",\"" + String(APN) + "\"");
  delay(1000);
  SIM800.println("AT+SAPBR=3,1,\"USER\",\"" + String(USERNAME) + "\"");
  delay(1000);
  SIM800.println("AT+SAPBR=3,1,\"PWD\",\"" + String(PASSWORD) + "\"");
  delay(1000);
  SIM800.println("AT+SAPBR=1,1");
  delay(1000);
  SIM800.println("AT+HTTPINIT");
  delay(1000);
  SIM800.println("AT+HTTPPARA=\"CID\",1");
  delay(1000);
}

void sendToThingSpeak(float temperature) {
  String url = "/update?api_key=" + String(THINGSPEAK_API_KEY) + "&field1=" + String(temperature);
  SIM800.println("AT+HTTPPARA=\"URL\",\"" + String(THINGSPEAK_HOST) + url + "\"");
  delay(1000);
  SIM800.println("AT+HTTPACTION=0");
  delay(15000); // Wait for the HTTP request to complete (adjust as needed)
  SIM800.println("AT+HTTPREAD");
  String response = readSerial();
  Serial.println("Response from ThingSpeak:");
  Serial.println(response);
}

void disconnectGPRS() {
  SIM800.println("AT+HTTPTERM");
  delay(1000);
  SIM800.println("AT+SAPBR=0,1");
  delay(1000);
  SIM800.println("AT+CGATT=0");
  delay(1000);
}

String readSerial() {
  String response = "";
  while (SIM800.available()) {
    char c = SIM800.read();
    response += c;
  }
  return response;
}