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I'm monitoring a temp and humidity sensor outside of my house using a ESP32. I have it update every 15 minutes. On my channel I have a chart and numeric readout. The readout shows me that it is updating every 15 minutes but the chart's last update was 2 hours ago. This was working until I went into the properties of the chart and changed the time base from daily to 12 hours. I have tried refreshing the page, signing out and back in as well as reboot the computer, still 2 hours behind. Is there something else I have to do to reestablish the chart?

Thanks John

If you are a student or researcher looking for a project idea, have a look at the MathWorks Excellence in Innovation site. There is at least one IoT-based project for a Smart watering system, and a project with a Digital twin of a pneumatic system. If you ask me, most of the other projects could also be enhanced with an IoT based component shared on ThingSpeak!

#include <Keypad.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SoftwareSerial.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);
SoftwareSerial ESP01(2, 3);

const byte ROWS = 4; // four rows
const byte COLS = 3; // three columns
char keys[ROWS][COLS] = { // keypad labels
  {'1', '2', '3'},
  {'4', '5', '6'},
  {'7', '8', '9'},
  {'*', '0', '#'}
};

byte rowPins[ROWS] = {12, 7, 8, 10};          //connect to keypad pins 12, 7, 8, 10
byte colPins[COLS] = {11, 13, 9};             // connect to keypad pins 11, 13, 9 column pinouts
Keypad customKeypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

#define Password_Length 5
#define DEBUG true
#define IP "184.106.153.149"

// define pin numbers
int buzzer = 5; // buzzer is connected to pin 5
int PIR = 6;    // PIR is connected to pin 6

// intruder alarm password
char Data[Password_Length];
char Master[Password_Length] = "1234";
byte data_count = 0, master_count = 0;
bool Pass_is_good;
char customKey;
int val = 0;

// thingspeak & WiFi
String apiKey = "xxxxxxxxxxxxxxxx"; // thingspeak API key

void setup() {
lcd.init(); 
lcd.backlight();
pinMode(buzzer, OUTPUT);
pinMode(PIR, INPUT);

Serial.begin(9600); 
while (!Serial){
}
Serial.println("Starting...");
ESP01.begin(9600);

// Reset ESP8266, put it into mode 1 i.e. STA only, make it join hotspot / AP, 
// establish single connection
ESP01.println();
sendData("AT+RST\r\n",2000,DEBUG);
sendData("AT+CWMODE=1\r\n",2000,DEBUG);
sendData("AT+CWJAP=\"AiPhone\",\"123889\"\r\n",20000,DEBUG);  
sendData("AT+CIPMUX=0\r\n",4000,DEBUG);

// Make TCP connection
String cmd = "AT+CIPSTART=\"TCP\",\"";
cmd += "184.106.153.149"; // Thingspeak.com's IP address  
cmd += "\",80\r\n";
sendData(cmd,4000,DEBUG);  

// Read PIR sensor value 
  val = digitalRead(PIR);
  // check if there was a state transition

    String val1 = String(val);
    if (val == HIGH)
    {
      Serial.println("Motion detected!");
      delay(10);
      Serial.println(val1);
    }
    else
    {
      Serial.println("Asleep");
      delay(10);
      //String val1 = String(val);
      Serial.println(val1);
    }
      //String val1 = String(val);
      //Serial.println(val1);

//Prepare GET string
String getStr = "GET /update?api_key=";
getStr += apiKey;
getStr += "&field1=";
getStr += val1;
getStr +="\r\n";

// Send data length & GET string
ESP01.print("AT+CIPSEND=");
ESP01.println (getStr.length());
Serial.print("AT+CIPSEND=");
Serial.println(getStr.length());
delay(500);
if(ESP01.find (">"))
{
  Serial.print(">");
  sendData(getStr, 2000, DEBUG);
}

//Close connection, wait a while before repeating
sendData("AT+CIPCLOSE", 16000, DEBUG); // 15 seconds delay between updates
}

if true
  % code
endvoid loop() {

if (digitalRead(PIR) == HIGH)
{
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Enter Password: ");

    customKey = customKeypad.getKey();
    if (customKey)
    {
      Data[data_count] = customKey;
      lcd.setCursor(data_count, 1);
      lcd.print(Data[data_count]);
      data_count++;
    }

    if (data_count == Password_Length - 1)
    {
      lcd.clear();

      if (!strcmp(Data, Master))
      {
        lcd.print("OK");
        digitalWrite(buzzer, HIGH);
        delay(200);
        digitalWrite(buzzer, LOW);
        delay(200);
        digitalWrite(buzzer, HIGH);
        delay(200);
        digitalWrite(buzzer, LOW);
      }
      else
      {
        lcd.print("Wrong Password");
        digitalWrite(buzzer, HIGH);
        delay(1000);
        digitalWrite(buzzer, LOW);
      }

      lcd.clear();
      clearData();
    }
  }
  else
    {
      lcd.noBacklight();      // turn backlight off
      lcd.clear();            // clear display
      delay(250);
    }
}

String sendData(String command, const int timeout, boolean debug)
{
  String response = "";
  ESP01.print(command);
  long int time = millis();

    while( (time+timeout) > millis())
    {
      while(ESP01.available())
      {
        // "Construct" response from ESP01 as follows 
         // - this is to be displayed on Serial Monitor. 
        char c = ESP01.read(); // read the next character.
        response+=c;
      }  
    }

    if(debug)
    {
      Serial.print(response);
    }

    return (response);
}

void clearData() {
  while (data_count != 0)
{
  Data[data_count--] = 0;
  }
  return;
}

I built a safe entry mechanism and i would like the matlab to send an email alert when arduino is not communicating or sending any data to thingspeak. How do i write the program to detect system down and to send email alert?

Hi, I want to send an alert to multiple email ids when a channel event occurs(for example:sensor temperature exceeds a threshold value).How can I do it?Help is highly appreciated. Thanks in Advance!

EL TERMÓMETRO QUEDO CLAVADO EN -127°, LO RESETEE PERO AUN NO FUNCIONA, POSRA SER LA ZONDA Y SI FUESE ASÍ COMO ADQUIRIRLA-

Hello, in the free usage of ThingSpeak, minimum data rate is 15 s. I have received a message that I will run messages in a month, and I would like to reduce the data rate, but I cannot find information of neither which is the current data rate that it's established in my channels, nor how might I modify it. I would like to reduce the rate at which I send data, as I actually do not need this rate to be high, but I cannot figure out how to do it. I am afraid I know little of how to "program" thingspeak, for creating my channels I followed the tutorials on "getting started with Thingspeak", and it worked quite well, but I have no idea which is the data rate that is being used or how to modify it. I will be really greatful if somebody may help me to learn how to do this.

Just getting started with Thingspeak, I'm reading temperature, humidity and pressure from a BME280 connected to a ESP32. I have both a chart and numeric display on my channels, works great.

Can I resize the visualizations to get more on the monitor at a time? Or can I add a numeric readout that will show the last value added to the chart? Both the chart and readout use the same field info. I do see that if I hover my mouse over a point on the chart I get the value but wanted to be displayed.

Thanks for any help John

Hi, this is my first question here... hope not to bother you all. Is it possible to stop a sensor from collecting data by using ThingSpeak/MQTT broker/MQTT protocol? How? I'm working with a MAX30102 for oxigen and bpm detection and I need to stop the sensor from ThingSpeak or at least this is what I was asked to do. At the moment I can't figure out how to do this except by using the APIkey and the HTTP protocol but my task was to only use MQTT protocol. Hope someone can help me finding a new point of view about this topic/problem.

EDIT: I solved the problem. I used another client, MQTTx to be precise, in order to send messages in a field of control. So, at the beginning I had just two fields (BPM and SpO2), then I added a third field of control. The board WeMos, connected to the sensor MH-ET LIVE MAX30102 was used to process the sensor's data and send them to Thingspeak every 15 seconds wherease the client desktop MQTTx was also connected to ThingSpeak's broker and enbled for both publish and subscribe and I used it to send messages of ON and OFF, literally, as payload for the control field. This messages were passed to the callBack function and the payload was checked in order to change the state of my code, nested in a switch system. Thamk's for the help to you all :) If you're interested to the code and the settings just let me know.

I would like a free account on Thingspeak for 1 device/channel using lorawan and < 300 messages a day for non-commercial (home) use. Today I received an email from MathWorks that my trial period ends. Somewhere I read I may have indicated commercial usage when starting the Thingspeak account. But I cannot find it in Thingspeak profile, nor in my Mathworks profile. How to change this?

El termómetro quedo tildado en -127°, lo desconecte en varias oportunidades y se encuentra tildado.

Hello! A few years ago i could write data to my thingspeak field with this code on arduino with ESP8266.

However today when i try this i only get errors. Instead I have to use this code. it is almost the same but connecting without SSL on port 80 instead.

Has anything changed on thingspeaks side? What do i do wrong? Here is a link to the full code if thats needed: https://github.com/kjellcompany/Arduino_701/blob/master/Thingspeak/Thingspeak.ino

Every day, thousands of people ask questions on MATLAB Answers and many of these are about their code. Questions such as “How can I make this faster?”, “Why do I get this error message?” or “Why don’t I get the answer I expect?”. There’s often one crucial thing missing though – the code in question!

Most of the people who answer questions on MATLAB Answers are volunteers from the community. They are answering your questions for fun, to learn more about MATLAB or just because they like to be helpful. This is even true for people such as me who are MathWorks members of staff. It’s not part of my role to patrol the community, looking where I can help out. I do it because I like to do it.

Make it easier to help me help you.

Imagine you’re a volunteer, looking for something interesting to answer. What kind of questions are you more likely to dig into and help an anonymous stranger figure out?

In my case, I almost always focus on problems that I can easily reproduce. I rarely know the answer to any question off the top of my head and so what I like to do is start off with the problem you are facing and use the various tools available to me such as the profiler or debugger to figure it out. This is the fun of it all for me – I almost always learn something by doing this and you get helped out as a side effect!

The easier I can reproduce your issue, the more likely I am to get started. If I can’t reproduce anything and the answer isn’t immediately obvious to me I’ll just move onto the next question. One example that demonstrates this perfectly is a case where someone’s MATLAB code was running too slowly. All of the code was available so I could run it on my machine, profile it and provide a speed-up of almost 150x.

It's not always feasible or desirable to post all of your code in which case you need to come up with a minimal, reproducible example. What’s the smallest amount of code and data you can post that I can run on my machine and see what you see? This may be more work for you but it will greatly increase your chances of receiving an answer to your question.