Is there any reason an Arduino Primo cannot send data to my ThingSpeak field?

Does the device need to have a secure protocol? The Primo does not.

[Vinod]

The Primo should be able to send data to ThingSpeak. Have you tried modifying one of the examples here: https://github.com/mathworks/thingspeak-arduino

That is a good starting point as those examples have all been tested to work and can give you some tips on programming the device correctly.

[Dale Lamb]

No, I was not aware of those examples. I have tried modifying the "Wireless Network Signal Strength with ESP32 with Arduino IDE", and it gets connected to the server, goes through all the client.print steps, no errors received but the data in the field doesn't change. Thanks for the response, that makes me think I might have something I can do to get it to work. I will publish it if I get it to work.

[Christopher Stapels]

As of March 13, there is an error in that ESP32 code. It disconnects before the server returns an answer. You can add delay and it will work. The code will be fixed soon.

I reccomend looking at the examples that Vinod shared. There is an ESP32 example for the library that works.

[Dale Lamb]

Got an error trying to compile using the Thingspeak library. The error was

C:\Users\daleg\Documents\Arduino\libraries\ThingSpeak\src/ThingSpeak.h:1647:35: error: 'dtostrf' was not declared in this scope. I have Arduino IDE version 1.8.12. there may be a newer version. (:

[Christopher Stapels]

I don't have a primo to try to reproduce your error.

Some of the forums I found suggested linking the avr library

include <avr/dtostrf.h>

If you search the error and arduino,there is a good deal of material out there.

https://github.com/arduino/Arduino/issues/9308

[Dale Lamb]

I included the avr/dtostrf.h to my script, compiler accepted it, but I still get the same error message on the dtostrf line in the ThingSpeak file. I also tried adding delays in the "Wireless Network Signal Strength" code (as suggested above) at several points but still get no update. Where does the delay go and how much delay is enough? Could the Primo's 32 bit "int" be causing problems?

[Christopher Stapels]

in the http request function, add some delay after the post is sent. 200 ms should do, but I suggest you start with 500 and work down.

     // POST data to ThingSpeak.
        if (client.connect(server, 80)) {
          
            client.println("POST /update HTTP/1.1");
            client.println("Host: api.thingspeak.com");
            client.println("Connection: close");
            client.println("User-Agent: Primo");
            client.println("X-THINGSPEAKAPIKEY: "+writeAPIKey);
            client.println("Content-Type: application/x-www-form-urlencoded");
            client.print("Content-Length: ");
            client.print(data.length());
            client.print("\n\n");
            client.print(data);
%             ADD DELAY HERE 
 delay(500);

            Serial.println("RSSI = " + String(field1Data));
            lastConnectionTime = millis();   
        }
    }
    client.stop();

Answer 1

[Dale Lamb]

It Worked!!!! I got it to work with a delay as low as 40 msec, but set it to 80 msec for margin.

Thank you Christopher Stapels for seeing me through this!

Recap: Send data to ThingSpeak using Arduino Primo

Two approaches were reccommended, approach 2 worked

1). The approach shown in https://github.com/mathworks/thingspeak-arduino did not work for my Primo, the error suggesting a problem with dtostrf, even when the library was added. Was unable to resolve due to my limited experience/time availability.

2). I modified Arduino IDE's Example/WifiLink/WifiWebClient.ino by swapping in the POST commands found in the ThingSpeak example "Wireless Network Signal Strength" with a delay added as per Christopher Stapels previous comment. Success was achieved. :)

[Christopher Stapels]

The bad example was my fault, so the least I can do is to see you through it. Thanks for letting me know it worked! I would still reccomend a bit more than 80 just to be safe. Unless you are really power strapped, 200 ms shouldnt hurt. The best thing to do is to actually poll for a response from the server, then you dont have to wait an arbitrary time. The ThingSpeak library does this, but I am sorry it wont compile for you. I read that you can also add a version of the dtostr function in the code yourself if you wish. Anyway, happy thingpseaking!