[RESOLVED] How to send data from my Arduino to Thingspeak using a GSM SIM800c ?

Hello :)

This is my first big project using Arduino components, so I don't really understand everything, that's why I encounter so many difficulties.

My goal is to send data from my ultrasonic sensor (HC-SR04) to Thingspeak using an Arduino UNO and a GSM SIM800c.

Material :

• Arduino UNO ;
• GSM SIM 800c shield (https://www.eagle-robotics.com/accueil/257-shield-sim800c-arduino.html) ;
• Ultrasonic sensor (HC-SR04) ;
• Cables for my ultrasonic sensor ;
• Cable to connect my Arduino to my computer.

I want to send data to Thinspeak from everywhere, so I can't use Wifi. I found a solution on google : https://github.com/707amitkumar/Send-Data-on-cloud-using-gsm-800c/blob/main/gsmangthingspeak.txt

In order to send data to my channel on thingspeak, I did use the code mentionned on the link and I just changed the part concerning the data to send (because I want to send data from my ultrasonic sensor) :

#include <SoftwareSerial.h>
SoftwareSerial gprsSerial(7,8);
 
#include <String.h>
#include <HCSR04.h>

const int trigPin = 2 ;
const int echoPin = 3 ;
UltraSonicDistanceSensor distanceSensor(trigPin, echoPin) ;
void setup()
{
  gprsSerial.begin(9600);               // the GPRS baud rate   
  Serial.begin(9600);    // the GPRS baud rate 
  delay(1000);
}
 
void loop()
{
  float distance = distanceSensor.measureDistanceCm();
  Serial.print("Distance = ");
  Serial.print(distance);
  Serial.println(" cm");
  
  if (gprsSerial.available())
    Serial.write(gprsSerial.read());
 
  gprsSerial.println("AT");
  delay(1000);
 
  gprsSerial.println("AT+CPIN?");
  delay(1000);
 
  gprsSerial.println("AT+CREG?");
  delay(1000);
 
  gprsSerial.println("AT+CGATT?");
  delay(1000);
 
  gprsSerial.println("AT+CIPSHUT");
  delay(1000);
 
  gprsSerial.println("AT+CIPSTATUS");
  delay(2000);
 
  gprsSerial.println("AT+CIPMUX=0");
  delay(2000);
 
  ShowSerialData();
 
  gprsSerial.println("AT+CSTT=\"tango.lu\"");//start task and setting the APN,
  delay(1000);
 
  ShowSerialData();
 
  gprsSerial.println("AT+CIICR");//bring up wireless connection
  delay(3000);
 
  ShowSerialData();
 
  gprsSerial.println("AT+CIFSR");//get local IP adress
  delay(2000);
 
  ShowSerialData();
 
  gprsSerial.println("AT+CIPSPRT=0");
  delay(3000);
 
  ShowSerialData();
  
  gprsSerial.println("AT+CIPSTART=\"TCP\",\"api.thingspeak.com\",\"80\"");//start up the connection
  delay(6000);
 
  ShowSerialData();
 
  gprsSerial.println("AT+CIPSEND");//begin send data to remote server
  delay(4000);
  ShowSerialData();
  
  String str="GET https://api.thingspeak.com/update?api_key=F2WFEAUL58M062LM&field1=0" + String(distance) ;
  Serial.println(str);
  gprsSerial.println(str);//begin send data to remote server
  
  delay(4000);
  ShowSerialData();
 
  gprsSerial.println((char)26);//sending
  delay(5000); //waitting for reply, important the time is base on the condition of internet 
  gprsSerial.println();
 
  ShowSerialData();
 
  gprsSerial.println("AT+CIPSHUT"); //close the connection
  delay(100);
  ShowSerialData();
} 
void ShowSerialData()
{
  while(gprsSerial.available()!=0)
  Serial.write(gprsSerial.read());
  delay(5000); 
  
}

When I run this code to my Arduino, I notice 2 problems :

1. The piece of information is "sent" to my Thingspeak Channel but it doesn't match with the data sent from my sensors (It always show "0" on Thingspeak while the sensor sends a positive value :

2. I can notice that my code doesn't run as well as expected because the Serial Monitor dislay this :

I really don't kow what to do... And I thank you in advance for any help you may give me.

I hope my english is not so bad and you cand understand me :)

I wish you a good day,

Cécilia.

Answer 1

[Christopher Stapels]

Seems like you have made a nice start on your first project! You seem pretty close to the goal.

Since you shared the API key, I was able to look at your private channel and see that you have entries corresponding to the data that I think you are interested in

{"created_at": "2022-01-11T13:55:33Z","entry_id": 10,"field1": "5.90"},

Is that the data you were looking for?

I would recommend using the API keys tab in your channel view to change your api key, then you will have to reprogram the device with the new API key. Then replace your API key with something else when you post. (i.e. "xxxxxxxxxxxxx") Once you change the API key, the key above will no longer work.

Its possible you might need additional delay in your command before disconnecting. If your device disconnects before ThingSpeak responds, ThingSpeak may not keep your data.

[Cécilia Facca]

Hello :)

Thanks for your answer !!

Actually, I just found what was the issue : I had the wrong APN on my AT command !!

I change it to : gprsSerial.println("AT+CSTT=\"internet\"") and everything works perfectly !

Tanks for your answer and your help :)

I wish you a good day.

[Ryan Khyle]

Good day Cecilia,

can you help me? I have the same project as well, can you drop the code that is working.. it will really help us and my groupmates thank you

[Rainer Gerald]

Same thing ma'am, can you drop the fixed code. It would really be a big help