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Hello guys:

I am having a problem with something I'm doing, I don't know whether it is something related to thingspeak or to my program. I am using Curl library in c to make Get requests to send data to my channel, those data are are measurments of my Analog Discovery 2 device and they are instantaneous, (using the AD2 SDK library which was uploaded recently, and in it they use thingspeak to send the measurments too) . However, the updating to my channel is happenning very slowly (every new sample update happens each 15 seconds). What do you think is causing the problem? is the updating to the channels is usually slow and you can't do thing kind of fast uploading? or is it something that my code fails to communicate with the channel properly. I attached a photo to my program which shows the status of the Curl Get requests (which demonstrates the connectivity problem). Appreciating any help.

Alberto Maccioni
Alberto Maccioni
Last activity on 14 Mar 2022

feeds.json vs status.json

Hello, I see a difference in the number of elements returned by: https://api.thingspeak.com/channels/1389063/status.json?offset=0&results=2500&api_key=XXXXXXXXXXXXXX and https://api.thingspeak.com/channels/1389063/feeds.json?offset=0&results=2500&status=true&api_key=XXXXXXXX The first returns only 271 elements, the second 2500 as requested. Why is that?

Adam Danz
Adam Danz
Last activity on 17 Mar 2022

New in MATLAB R2022a: Fontsize scaling

You've spent hours designing the perfect figure and now it's time to add it to a presentation or publication but the font sizes in the figure are too small to see for the people in the back of the room or too large for the figure space in the publication. You've got titles, subtitles, axis labels, legends, text objects, and other labels but their handles are inaccessible or scattered between several blocks of code. Making your figure readable no longer requires digging through your code and setting each text object's font size manually.

Starting in MATLAB R2022a, you have full control over a figure's font sizes and font units using the new fontsize function (see release notes ).

Use fontsize() to

  • Set FontSize and FontUnits properties for all text within specified graphics objects
  • Incrementally increase or decrease font sizes
  • Specify a scaling factor to maintain relative font sizes
  • Reset font sizes and font units to their default values . Note that the default font size and units may not be the same as the font sizes/units set directly with your code.

When specifying an object handle or an array of object handles, fontsize affects the font sizes and font units of text within all nested objects.

While you're at it, also check out the new fontname function that allows you to change the font name of objects in a figure!

Give the new fontsize function a test drive using the following demo figure in MATLAB R2022a or later and try the following commands:

% Increase all font sizes within the figure by a factor of 1.5
fontsize(fig, scale=1.5)

% Set all font sizes in the uipanel to 16
fontsize(uip, 16, "pixels")

% Incrementally increase the font sizes of the left two axes (x1.1)
% and incrementally decrease the font size of the legend (x0.9)
fontsize([ax1, ax2], "increase")
fontsize(leg, "decrease")

% Reset the font sizes within the entire figure to default values
fontsize(fig, "default")

% Create fake behavioral data
rng('default')
fy = @(a,x)a*exp(-(((x-8).^2)/(2*3.^2)));
x = 1 : 0.5 : 20;
y = fy(32,x);
ynoise = y+8*rand(size(y))-4;
selectedTrial = 13;

% Plot behavioral data
fig = figure('Units','normalized','Position',[0.1, 0.1, 0.4, 0.5]);
movegui(fig, 'center')
tcl = tiledlayout(fig,2,2); 
ax1 = nexttile(tcl); 
hold(ax1,'on')
h1 = plot(ax1, x, ynoise, 'bo', 'DisplayName', 'Response');
h2 = plot(ax1, x, y, 'r-', 'DisplayName', 'Expected');
grid(ax1, 'on')
title(ax1, 'Behavioral Results')
subtitle(ax1, sprintf('Trial %d', selectedTrial))
xlabel(ax1, 'Time (seconds)','Interpreter','Latex')
ylabel(ax1, 'Responds ($\frac{deg}{sec}$)','Interpreter','Latex')
leg = legend([h1,h2]);

% Plot behavioral error
ax2 = nexttile(tcl,3);
behavioralError = ynoise-y; 
stem(ax2, x, behavioralError)
yline(ax2, mean(behavioralError), 'r--', 'Mean', ...
    'LabelVerticalAlignment','bottom')
grid(ax2, 'on')
title(ax2, 'Behavioral Error')
subtitle(ax2, ax1.Subtitle.String)
xlabel(ax2, ax1.XLabel.String,'Interpreter','Latex')
ylabel(ax2, 'Response - Expected ($\frac{deg}{sec}$)','Interpreter','Latex')

% Simulate spike train data
ntrials = 25; 
nSamplesPerSecond = 3; 
nSeconds = max(x) - min(x); 
nSamples = ceil(nSeconds*nSamplesPerSecond);
xTime = linspace(min(x),max(x), nSamples);
spiketrain = round(fy(1, xTime)+(rand(ntrials,nSamples)-.5));
[trial, sample] = find(spiketrain);
time = xTime(sample);

% Spike raster plot
axTemp = nexttile(tcl, 2, [2,1]);
uip = uipanel(fig, 'Units', axTemp.Units, ...
    'Position', axTemp.Position, ...
    'Title', 'Neural activity', ...
    'BackgroundColor', 'W');
delete(axTemp)
tcl2 = tiledlayout(uip, 3, 1);
pax1 = nexttile(tcl2); 
plot(pax1, time, trial, 'b.', 'MarkerSize', 4)
yline(pax1, selectedTrial-0.5, 'r-', ...
    ['\leftarrow Trial ',num2str(selectedTrial)], ...
    'LabelHorizontalAlignment','right', ...
    'FontSize', 8); 
linkaxes([ax1, ax2, pax1], 'x')
pax1.YLimitMethod = 'tight';
title(pax1, 'Spike train')
xlabel(pax1, ax1.XLabel.String)
ylabel(pax1, 'Trial #')

% Show MRI
pax2 = nexttile(tcl2,2,[2,1]); 
[I, cmap] = imread('mri.tif');
imshow(I,cmap,'Parent',pax2)
hold(pax2, 'on')
th = 0:0.1:2*pi; 
plot(pax2, 7*sin(th)+84, 5*cos(th)+90, 'r-','LineWidth',2)
text(pax2, pax2.XLim(2), pax2.YLim(1), 'ML22a',...
    'FontWeight', 'bold', ...
    'Color','r', ...
    'VerticalAlignment', 'top', ...
    'HorizontalAlignment', 'right', ...
    'BackgroundColor',[1 0.95 0.95])
title(pax2, 'Area of activation')

% Overall figure title
title(tcl, 'Single trial responses')

This Community Highlight is attached as a live script.

I am working with an Arduino nodemcu board and a Tmp36 sensor. My channel updates fine if I use my browser with the following: https://api.thingspeak.com/update?api_key=xxxxxxxxx&field1=71, but does not update with the following sketch, although the serial monitor shows the commands are executed:

//Source code to the Temperature Sensor and ThingSPeak Server Blog
String ssid     = "XXX";  // SSID to connect to
String password = "XXX"; // Our virtual wifi has no password (so dont do your banking stuff on this network)
String host     = "api.thingspeak.com"; // Open Weather Map API
const int httpPort   = 443;
String uri     = "/update?api_key=XXXX&field1=";

int setupESP8266(void) {
  // Start our ESP8266 Serial Communication
  Serial.begin(115200);   // Serial connection over USB to computer
  Serial.println("AT");   // Serial connection on Tx / Rx port to ESP8266
  delay(10);        // Wait a little for the ESP to respond
  if (!Serial.find("OK")) return 1;

    // Connect to 123D Circuits Simulator Wifi
    Serial.println("AT+CWJAP=\"" + ssid + "\",\"" + password + "\"");
    delay(10);        // Wait a little for the ESP to respond
    if (!Serial.find("OK")) return 2;
    // Open TCP connection to the host:
    Serial.println("AT+CIPSTART=\"TCP\",\"" + host + "\"," + httpPort);
    delay(50);        // Wait a little for the ESP to respond
    if (!Serial.find("OK")) return 3;
    return 0;
  }
void anydata(void) {

    int temp = map(analogRead(A0),20,358,-40,125);
    // Construct our HTTP call
    String httpPacket = "GET " + uri + String(temp) + " HTTP/1.1\r\nHost: " + host + "\r\n\r\n";
    int length = httpPacket.length();
    // Send our message length
    Serial.print("AT+CIPSEND=");
    Serial.println(length);
    delay(10); // Wait a little for the ESP to respond if (!Serial.find(">")) return -1;
    // Send our http request
    Serial.print(httpPacket);
    delay(1000); // Wait a little for the ESP to respond
    if (!Serial.find("SEND OK\r\n")) return;
}

void setup() {

    setupESP8266();
}

void loop() {

   anydata();
    delay(10000);
  }

hello, i have done my iot project using thingspeak as the monitoring source and its working well and good.But now i need get text message to a mobile when the field value gets reached to given threshold value and i have to get a alert text message.Is there any way to resolve my problem from thigspeak data to alert text message.

Thankyou.

Hi,

I am using Ublox SARA-R410M to send (cellular) data to ThingSpeak cloud. I found in the Ublox manual that AT+UHTTPC (POST data command) can do the job. The link below is the location which my data will be saved on ThingSpeak (field1):

"https://api.thingspeak.com/update?api_key=WRITE_API_KEY&field1="

Note that the "WRITE_API_KEY" is 16 characters (combination of letters and numbers).

AT command: AT+UHTTPC=<profile_id>,5, path,<filename>,<data>,<HTTP_content_type>

Based on the information above, which items should I use for path and filename? And how can I use this command in Arduino code?

I appreciate any help in advance.

Abbas

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6178 votes

Hi,

I am using a Sparkfun LTE Shield with a SARA-R410M-02B-01 cellular module, an Arduino UNO, and an AT&T simcard to send data to ThingSpeak. I used "AT+UDNSRN" on Arduino code (below) to find IP address of "api.thingspeak.com". I found two different IPs using this command: "3.224.210.136","3.213.58.187" (also, nslookup command on CMD Windows gives me these IPs). Moreover, I found that some websites report "184.106.153.149" as ThingSpeak's IP. I used the "AT+USOCO" on Arduino code (below) for TCP connection using these three IPs:

Example of the Arduino codes:

lteSerial.println("AT+UDNSRN=0,\"api.thingspeak.com\""); //Find IP address

lteSerial.println("AT+USOCO=0,\"184.106.153.149\",\"80\""); //TCP Connection to ThingSpeak using IP address

But I got this error (for "AT+USOCO" command):

+CME ERROR: Operation not allowed

Any idea regarding which IP address should I use for "api.thingspeak.com"?

I appreciate any help in advance.

Abbas

Introduction
Comma-separated lists are really very simple. You use them all the time. Here is one:
a,b,c,d
That is a comma-separated list containing four variables, the variables a, b, c, and d. Every time you write a list separated by commas then you are writing a comma-separated list. Most commonly you would write a comma-separated list as inputs when calling a function:
fun(a,b,c,d)
or as arguments to the concatenation operator or cell construction operator:
[a,b,c,d]
{a,b,c,d}
or as function outputs:
[a,b,c,d] = fun();
It is very important to understand that in general a comma-separated list is NOT one variable (but it could be). However, sometimes it is useful to create a comma-separated list from one variable (or define one variable from a comma-separated list), and MATLAB has several ways of doing this from various container array types:
1) from a field of a structure array using dot-indexing:
struct_array.field % all elements
struct_array(idx).field % selected elements
2) from a cell array using curly-braces:
cell_array{:} % all elements
cell_array{idx} % selected elements
3) from a string array using curly-braces:
string_array{:} % all elements
string_array{idx} % selected elements
Note that in all cases, the comma-separated list consists of the content of the container array, not subsets (or "slices") of the container array itself (use parentheses to "slice" any array). In other words, they will be equivalent to writing this comma-separated list of the container array content:
content1, content2, content3, .. , contentN
and will return as many content arrays as the original container array has elements (or that you select using indexing, in the requested order). A comma-separated list of one element is just one array, but in general there can be any number of separate arrays in the comma-separated list (zero, one, two, three, four, or more). Here is an example showing that a comma-separated list generated from the content of a cell array is the same as a comma-separated list written explicitly:
>> C = {1,0,Inf};
>> C{:}
ans =
1
ans =
0
ans =
Inf
>> 1,0,Inf
ans =
1
ans =
0
ans =
Inf
How to Use Comma-Separated Lists
Function Inputs: Remember that every time you call a function with multiple input arguments you are using a comma-separated list:
fun(a,b,c,d)
and this is exactly why they are useful: because you can specify the arguments for a function or operator without knowing anything about the arguments (even how many there are). Using the example cell array from above:
>> vertcat(C{:})
ans =
1
0
Inf
which, as we should know by now, is exactly equivalent to writing the same comma-separated list directly into the function call:
>> vertcat(1,0,Inf)
ans =
1
0
Inf
How can we use this? Commonly these are used to generate vectors of values from a structure or cell array, e.g. to concatenate the filenames which are in the output structure of dir:
S = dir(..);
F = {S.name}
which is simply equivalent to
F = {S(1).name, S(2).name, S(3).name, .. , S(end).name}
Or, consider a function with multiple optional input arguments:
opt = {'HeaderLines',2, 'Delimiter',',', 'CollectOutputs',true);
fid = fopen(..);
C = textscan(fid,'%f%f',opt{:});
fclose(fid);
Note how we can pass the optional arguments as a comma-separated list. Remember how a comma-separated list is equivalent to writing var1,var2,var3,..., then the above example is really just this:
C = textscan(fid,'%f%f', 'HeaderLines',2, 'Delimiter',',', 'CollectOutputs',true)
with the added advantage that we can specify all of the optional arguments elsewhere and handle them as one cell array (e.g. as a function input, or at the top of the file). Or we could select which options we want simply by using indexing on that cell array. Note that varargin and varargout can also be useful here.
Function Outputs: In much the same way that the input arguments can be specified, so can an arbitrary number of output arguments. This is commonly used for functions which return a variable number of output arguments, specifically ind2sub and gradient and ndgrid. For example we can easily get all outputs of ndgrid, for any number of inputs (in this example three inputs and three outputs, determined by the number of elements in the cell array):
C = {1:3,4:7,8:9};
[C{:}] = ndgrid(C{:});
which is thus equivalent to:
[C{1},C{2},C{3}] = ndgrid(C{1},C{2},C{3});
Further Topics:
MATLAB documentation:
https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html
https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html
https://www.mathworks.com/company/newsletters/articles/matlab-tips-and-tricks-exploiting-the-comma-separated-list-vectorizing-cell-array-and-structure-references.html
Click on these links to jump to relevant comments below:
Dynamic Indexing (indexing into arrays with arbitrary numbers of dimensions)
Nested Structures (why you get an error trying to index into a comma-separated list)
Summary
Just remember that in general a comma-separated list is not one variable (although they can be), and that they are exactly what they say: a list (of arrays) separated with commas. You use them all the time without even realizing it, every time you write this:
fun(a,b,c,d)

I visualise my data with ThingSpeak (data from The Thing Network) and I would like to have something like a button to send a command (downlink). I can send downlink with the thing network but I would like : The thing speak (for interface) -> the thing network (for lora gateway management) -> my device I see talkback and some example with wifi node but it is not my case... Thank you for your reply

I have a fish feeder project running on an Arduino esp 32, it checks various parameter and feeds according to temperature. Unfortunately it has stopped, it no-longer talks to thingspeak and hence cannot upload data. I believe I have a free licence (according to thingspeak) I was only using 1 channel, hence 4 sufficient at this moment. How can I get it working again, ps feeding starts May!. I have googled and understand notice may have been given. Help please- relatively new to Arduino's and first project to us thingspeak. at the moment wireless communication appears more reliable.

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DACE INP
DACE INP
Last activity on 23 Feb 2022

Se interrumpe el envio de datos

Hola, mi proyecto es con NodeMcu ESP8266, en el puerto serial obtengo datos cada 2 minutos asi esta programado, en la grafica salta datos y algunas veces durante una hora o mas, Qoe podria hacer?

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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;
}