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I have a google gauge that shows my PM2.5 sensor values but I would like to make 3 gauges appear side by side that show the value of different sensors. How can I do that? Thanks

Hello everyone, I am new to ThingSpeak and ESP32, I would like to send IMU sensor acceleration data from my ESP32 to ThingSpeak so that I can use this data for further analysis. I have tried the example code provided in this link: Bulk-Update and this works perfectly fine for me with the default update interval and post interval. I also attached the code here.

#include <Wire.h>
#include <Arduino.h>
#include <Adafruit_MCP4725.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BNO055.h>
#include <utility/imumaths.h>
#include <WiFi.h>
#include "ThingSpeak.h"

// Define multiplexer address
#define TCAADDR 0x70

// Define imu and dac objects
Adafruit_BNO055 bno = Adafruit_BNO055(55, 0x28);

char jsonBuffer[500] = "[";

char ssid[] = "my ssid";
char pass[] = "my password";
WiFiClient client;

char server[] = "api.thingspeak.com";

unsigned long lastConnectionTime = 0;
unsigned long lastUpdateTime = 0;
const unsigned long postingInterval = 15L * 1000L;
const unsigned long updateInterval = 3L * 100L;

// To choose the multiplexer specific channel (between 0 and 7)
void tcaselect(uint8_t i){
  if (i > 7) return;

Wire.beginTransmission(TCAADDR);
Wire.write(1 << i);
Wire.endTransmission();
}

    void setup() {
      // put your setup code here, to run once:
  Wire.begin();
  Serial.begin(9600);
  while(!Serial);
  delay(1000);
  Serial.println("Serial communication set up");

// set up bno055
tcaselect(2);
if (!bno.begin()){
  Serial.println("Failed to connect to BNO055");
  while (1);
}

while(WiFi.status() != WL_CONNECTED){
  Serial.print("Attempting to connect to wifi");
  WiFi.begin(ssid, pass);
  delay(5000);
}
Serial.println("Connected to WiFi");
printWiFiStatus();
}

void loop() {
  // put your main code here, to run repeatedly.

if (millis() - lastUpdateTime >= updateInterval){
  updatesJson(jsonBuffer);
}
}

void updatesJson(char* jsonBuffer){
  /* JSON format for updates paramter in the API
   *  This examples uses the relative timestamp as it uses the "delta_t". You can 
also provide the absolute timestamp using the "created_at" parameter
 *  instead of "delta_t".
 *   "[{\"delta_t\":0,\"field1\":-70},{\"delta_t\":3,\"field1\":-66}]"
 */
// Format the jsonBuffer as noted above
strcat(jsonBuffer,"{\"delta_t\":");
unsigned long deltaT = (millis() - lastUpdateTime)/1000;
size_t lengthT = String(deltaT).length();
char temp[4];
String(deltaT).toCharArray(temp,lengthT+1);
strcat(jsonBuffer,temp);
strcat(jsonBuffer,",");

tcaselect(2);
sensors_event_t orientationData , angVelocityData , linearAccelData, magnetometerData, accelerometerData, gravityData;

bno.getEvent(&orientationData, Adafruit_BNO055::VECTOR_EULER);
bno.getEvent(&angVelocityData, Adafruit_BNO055::VECTOR_GYROSCOPE);
bno.getEvent(&linearAccelData, Adafruit_BNO055::VECTOR_LINEARACCEL);

float rssi = linearAccelData.acceleration.x; 
strcat(jsonBuffer, "\"field1\":");
lengthT = String(rssi).length();
String(rssi).toCharArray(temp,lengthT+1);
strcat(jsonBuffer,temp);
strcat(jsonBuffer,"},");
// If posting interval time has reached 15s, update the ThingSpeak channel with your 
data
if (millis() - lastConnectionTime >=  postingInterval) {
      size_t len = strlen(jsonBuffer);
      jsonBuffer[len-1] = ']';
      httpRequest(jsonBuffer);
}
lastUpdateTime = millis(); // Update the last update time
}

// Updates the ThingSpeakchannel with data
void httpRequest(char* jsonBuffer) {
/* JSON format for data buffer in the API
 *  This examples uses the relative timestamp as it uses the "delta_t". You can also 
provide the absolute timestamp using the "created_at" parameter
 *  instead of "delta_t".
 *   "{\"write_api_key\":\"YOUR-CHANNEL-WRITEAPIKEY\",\"updates\": 
[{\"delta_t\":0,\"field1\":-60},{\"delta_t\":15,\"field1\":200}, 
{\"delta_t\":15,\"field1\":-66}]
 */
// Format the data buffer as noted above
char data[500] = "{\"write_api_key\":\"59IISQVOXV5GGH0D\",\"updates\":"; // Replace 
YOUR-CHANNEL-WRITEAPIKEY with your ThingSpeak channel write API key
strcat(data,jsonBuffer);
strcat(data,"}");
// Close any connection before sending a new request
client.stop();
String data_length = String(strlen(data)+1); //Compute the data buffer length
Serial.println(data);
// POST data to ThingSpeak
if (client.connect(server, 80)) {
  client.println("POST /channels/1683708/bulk_update.json HTTP/1.1"); // Replace 
YOUR-CHANNEL-ID with your ThingSpeak channel ID
  client.println("Host: api.thingspeak.com");
  client.println("User-Agent: mw.doc.bulk-update (Arduino ESP8266)");
  client.println("Connection: close");
  client.println("Content-Type: application/json");
  client.println("Content-Length: "+data_length);
  client.println();
  client.println(data);
}
else {
  Serial.println("Failure: Failed to connect to ThingSpeak");
}
delay(250); //Wait to receive the response
client.parseFloat();
String resp = String(client.parseInt());
Serial.println("Response code:"+resp); // Print the response code. 202 indicates that 
the server has accepted the response
jsonBuffer[0] = '['; //Reinitialize the jsonBuffer for next batch of data
jsonBuffer[1] = '\0';
lastConnectionTime = millis(); //Update the last conenction time
}

void printWiFiStatus() {
  // Print the SSID of the network you're attached to:
  Serial.print("SSID: ");
  Serial.println(WiFi.SSID());

// Print your device IP address:
IPAddress ip = WiFi.localIP();
Serial.print("IP Address: ");
Serial.println(ip);

// Print the received signal strength:
long rssi = WiFi.RSSI();
Serial.print("signal strength (RSSI):");
Serial.print(rssi);
Serial.println(" dBm");
}

However, when I tried to change the update interval to 0.3s (30Hz), the following error massage was given in the Arduino monitor: Guru Meditation Error: Core 1 panic'ed (LoadProhibited). Exception was unhandled.

Could someone please help me with this issue. If anything else is needed, I will update immediately.

Many thanks

I saw this problem online recently.

Passenger distribution on a train

Not a terribly difficult problem to solve. But it was mildly interesting to find a solution using MATLAB. Perhaps just as interesting is the post analysis of the problem to understand what is happening, and why any unique solution exists at all for one specific car.

The question is, we have a passenger train with 11 cars in it. Feel free to number them 1 through 11. We know that 381 passengers boarded the train. Every passenger is in one of the cars, but all we know is there are exactly 99 passengers in every set of three consecutive cars. Now the question becomes, how many passengers are in car number 9?

One might say at first this is impossible to know. Surely there are many ways the passengers may be arranged, but is that true? Could it be impossible to solve?

First, before we go any further, a few tests seem important. Logically, we might think to distribute 33 passengers in every car. Would that work? So we would have a passenger distribution of

X1 = repmat(33,11,1)

X1 =
    33
    33
    33
    33
    33
    33
    33
    33
    33
    33
    33

While that satisfies the requirement of every 3 consecutive cars having 99 passengers, it fails the total count requirement, since we can see the sum of all passengers would be 363. This yields too few total passengers, with only a combined load of 363 passengers, and we need 381.

At the other end of the spectrum is another extreme case. We might have this distribution:

X2 = zeros(11,1);
X2(1:3:11) = 99
X2 =
    99
     0
     0
    99
     0
     0
    99
     0
     0
    99
     0

Again, it meets the requirement that the sum of passengers in any 3 consecutiuve cars will be 99. But that case yields too many total passengers at 396. Somewhere in the middle must/might/may be a solution, right? At least it is good to see that we can have more or less than 381 total passengers. But how can we find a solution using MATLAB?

There is one other problem with the X2 attempt at a solution, in that had I chosen a different first car to place the 99 passengers, we need not have a unique result in car number 9.

X3 = zeros(11,1);
X3(2:3:11) = 99;

X4 = zeros(11,1);
X4(3:3:11) = 99;

Each of those schemes would put 99 passengers in every set of 3 consecutive cars.

[X2,X3,X4]
ans =
    99     0     0
     0    99     0
     0     0    99
    99     0     0
     0    99     0
     0     0    99
    99     0     0
     0    99     0
     0     0    99
    99     0     0
     0    99     0

But car number 9 would have very different numbers of passengers, depending on the choice made, either 0 or 99 passengers.

An obvious solution is to look for a code that can solve such a problem for us. INTLINPROG stands out as the perfect tool, as this is a linear problem, with everything being in the form of a sum. The unknowns will be how many passengers are sitting in each car. There are 11 cars. So there are 11 unknowns. The bounds are simple.

lb = zeros(1,11); % There cannot be less than zero passengers in any car.
ub = repmat(99,1,11); % since the sum of any three consecutive cars is 99, we cannot have more than 99 people in any one car.

All of the unknown car counts must be integer. That is, we cannot have a fractional number of people in a car, unless this is part of an Agatha Christie murder mystery.

intcon = 1:11;

What constraints apply? First, the sum of all passengers on the train must be 381.

As well, we know that in every 3 consecutive cars, the sum must be 99. Both constraints will take the form of exact linear equality constraints. We can encode all of that into the matrix Aeq, and the vector Beq.

Aeq = [ones(1,11);triu(tril(ones(9,11),2))]; % A tricky way to create the matrix Aeq
Beq = [381;repmat(99,9,1)];

If X is a potential solution that satisfies the bound constraints, it must satisfy the matrix equation Aeq*X==Beq.

We can see for example, the potential solutions I posed above as X1,...X4, all fail to satisfy the requirement on the total number of passengers, since while the sums for consecutive cars are correct, the total sum is not.

Aeq*[X1,X2,X3,X4]
ans =
   363   396   396   297
    99    99    99    99
    99    99    99    99
    99    99    99    99
    99    99    99    99
    99    99    99    99
    99    99    99    99
    99    99    99    99
    99    99    99    99
    99    99    99    99

Finally, there are no linear inequality constraints.

A = [];
B = [];

At this point, you might be wondering how we can formulate this as a linear programming problem at all. What would be the objective function? What could we hope to minimize? As it turns out, linear programming tools are pretty simple in that respect. We could pose just about any objective we want. For example, this is sufficient:

f = ones(1,11);

Effectively, we are just using intlinprog to see if a FEASIBLE integer solution exists that satisfies all of the bounds, as well as the equality constraints. This is why the objective can be the same as one of the equality constraints. Once INTLINPROG finds any solution, it will be done.

And now we can throw the problem into INTLINPROG, hoping something intelligent falls out.

[X,~,EXITFLAG] = intlinprog(f,intcon,A,B,Aeq,Beq,lb,ub)
P:                Optimal objective value is 381.000000.                                           

Optimal solution found.

Intlinprog stopped at the root node because the objective value is within a gap tolerance of the optimal value,
options.AbsoluteGapTolerance = 0 (the default value). The intcon variables are integer within tolerance,
options.IntegerTolerance = 1e-05 (the default value).

X =
     0
    84
    15
     0
    84
    15
     0
    84
    15
     0
    84
EXITFLAG =
     1

intlinprog has found a solution,

isequal(Aeq*X,Beq)
ans =
  logical
   1

The solution satisfies all of the constraints. Effectively, we see the repeating sub-sequence [0 84 15] in consecutive cars. And of course, as long as we repeat that sequence, it does satisfy all requirements. How many people are sitting in car number 9? 15 people.

Symmetry would suggest that car number 3 must have the same number of people, since we could as easily have numbered the cars starting from either end. And of course, X(3) was also 15.

Thankfully our intuition works there. It would seem we are done now. Or are we?

For some of you, you might be wondering if any other solutions can possibly exist. And some of you might be wondering if any of those solutions can have some other number of passengers than exactly 15 in cars number 3 and 9.

NULL is the MATLAB function to come to the rescue here.

This is essentially a linear algebra question. We wish to know the solutions of the problem Aeq*x==Beq. Here, Aeq is a 10x11 matrix, so it has rank at most 10. That means there is a vector Y, such that Aeq*Y == 0.

Y = double(null(sym(Aeq)))
Y =
    -1
     1
     0
    -1
     1
     0
    -1
     1
     0
    -1
     1

What does that tell us? If we have some particular solution (X) to the non-homogeneous problem Aeq*X==Beq, then the set of all possible solutions will be of the general form

syms t
X + t*Y
ans =
    -t
t + 84
    15
    -t
t + 84
    15
    -t
t + 84
    15
    -t
t + 84

You may see that this generates all solutions to the general problem. We can see a few of them in this array:

[X-1*Y, X - 2*Y, X - 3*Y, X - 84*Y]
ans =
     1     2     3    84
    83    82    81     0
    15    15    15    15
     1     2     3    84
    83    82    81     0
    15    15    15    15
     1     2     3    84
    83    82    81     0
    15    15    15    15
     1     2     3    84
    83    82    81     0

We see now there are 85 such possible integer solutions, all of the form X-k*Y, where k can be any positive integer from 0 to 84 inclusive. INTLINPROG found one of them. But as importantly, do you see that since the elements

Y([3 6 9])
ans =
     0
     0
     0

are all identically zero, that those elements in the solution can never change? Those cars must always contain exactly 15 passengers for all of the constraints to be satisfied. I'll be honest, it is not at all obvious as to why it works out that way, at least not initially in my eyes. That leaves my intuition wanting, just a bit.

How might we analyze this problem in a different way? Perhaps a different approach would yield a more satisfying solution. Suppose we chose a passenger partitioning that is strictly repetitive? For example, choose three non-negative integers u,v,w, such that u+v+w=99.

Now, fill the cars using the sequence

syms u v w
X = [u v w u v w u v w u v];

Surely you would agree that any subset of 3 consecutive cars adds to 99, as long as u+v+w=99. But then the sum of all 11 cars in that sequence must be 4*u+4v+3*w. And this leaves us with now two equations in three unknowns. We have

EQ1 = sum(X) == 381;
EQ2 = u + v + w == 99;

The rest is easy now, as we can do

EQ1 - 3*EQ2
ans =
u + v == 84

So if a solution in this form exists, we can see that u+v=84, and therefore w=99-u-v=15. (Remember that w was the number of passengers in car number 9, but also in cars numbered 3 and 6.) Any combination of non-negative integers that sums to 84 will work for u and v though.

This constructive approach does not insure it is the ONLY solution, since I built it from the sequence in the vector X. Perhaps a solution exists that is not simply repetitive as I created it. In fact, the previous analysis using null told us the whole story.

Starting in MATLAB R2022a, use the append option in exportgraphics to create GIF files from animated axes, figures, or other visualizations.

This basic template contains just two steps:

% 1. Create the initial image file
gifFile = 'myAnimation.gif';
exportgraphics(obj, gifFile);

% 2. Within a loop, append the gif image
for i = 1:20

      %   %   %   %   %   %    % 
      % Update the figure/axes %
      %   %   %   %   %   %    % 

      exportgraphics(obj, gifFile, Append=true);
  end

Note, exportgraphics will not capture UI components such as buttons and knobs and requires constant axis limits.

To create animations of images or more elaborate graphics, learn how to use imwrite to create animated GIFs .

Share your MATLAB animated GIFs in the comments below!

See Also

• Animation Techniques
• Animating plots

This Community Highlight is attached as a live script

I want to scale A and B (shown in a picture below) from a known dimension (base of tail light) from an image of an assembled car. The purpose is to get factory dimensions prior to welding my car together because I replaced both quarters, trunk pan, and trunk drop-offs. I replaced the frame rails. I made tubular ones in an effort to make them stronger. The installation of the tail panel will tie everything together. I want to make sure it's right.

Hello!

I`ve got problems with reading last input of a channel field using AT commands, here follows the sketch I'm currently using:

/* String tx_data_r = "GET https://api.thingspeak.com/channels/CHANNEL/fields/4/last.txt?api_key=API_READ_KEY&results=1"; */

String tx_data_r = "GET https://api.thingspeak.com/channels/";
tx_data_r += "CHANNEL";                                                                         
tx_data_r += "/";
tx_data_r += "fields";                                                                    
tx_data_r += "/4/";                                                                            
tx_data_r += "last.txt?api_key=";
tx_data_r += "API_READ_KEY";                                                                 
tx_data_r += "&results=1";                                                                   
tx_data_r += "\r\n";

Serial.print("AT+CIPSEND=");                                                                                                                                              
delay(1000);

Serial.println(tx_data_r.length());                                                                                                                                    
delay(1000);

Serial.println(tx_data_r);
delay(1000);

 This piece of code doesn`t return a valid response, however if I copy/paste
 https://api.thingspeak.com/channels/CHANNEL/fields/4/last.txt?api_key=API_READ_KEY&results=1"
 using a browser I get the right data.

 One more thing, if instead of using a microcontroller I use an USB serial PC interface program  directly connected to 
 my RF module, with                                                                      
 GET https://api.thingspeak.com/channels/CHANNEL/fields/4/last.txt?api_key=API_READ_KEY&results=1
 along with other commands I get the right data too!

 Can anybody tell me what's going on?

 There are no problems with any read related commands.

 If a working sketch is available it will be most welcome!

 Tks in advance for any help! 

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.

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?

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

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

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.

If you are interested in live script lecture notes in the following areas, take a look at the short course ( Advanced MATLAB for Scientific Computing ) developed at Stanford. You can also download the required data for the examples from the course GitHub page.

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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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