Getting authentication failure when using POST from ESP32

Trying to POST a CSV bulk update to update my channel.

Failing and getting

"401" as an http error code, and

"Please provide proper authentication details." as body.

Same thing does work with CURL.

What am I missing ????

thanks for the help.

#include <Arduino.h>
const char* ssid =    "XXX";
const char* password = "XXX";

#include <WiFi.h>
#include <WiFiMulti.h>
#include <HTTPClient.h>
#include <WiFiClientSecure.h>


void setup() {

Serial.begin(115200);
initiateNetwork();
thingsSpeakLogger();
}

void loop() {}

int thingsSpeakLogger(){

  WiFiClientSecure *client = new WiFiClientSecure;
  HTTPClient https;

  String payload = "write_api_key=XXXXXXXXXXX&time_format=relative&updates=4,1.1,2,0.3,,,6,7.7,0.8,41.2,19.5,100,ok|3,1,2,3,4,5,6,7,8,41.2,25.1,110,rising";
  String connectionString = "https://api.thingspeak.com/channels/12345678/bulk_update.csv";

  if (https.begin(*client, connectionString)) {

    https.addHeader("Content-Type", "x-www-form-urlencoded"); 
    
    Serial.println(https.POST(payload));  
    
    Serial.println(https.getString());
    delete client;

  }
}



void initiateNetwork() {

  WiFi.begin(ssid, password);  delay(1000);
  while (WiFi.status() != WL_CONNECTED)  {
    delay(300);  Serial.print(".");
  }
}

Answer 1

[Vinod]

Have you taken a look at this example:

https://www.mathworks.com/help/thingspeak/continuously-collect-data-and-bulk-update-a-thingspeak-channel-using-an-arduino-mkr1000-board-or-an-esp8266-board.html

[Christopher Stapels]

The example Vinod shared should work well on ESP 32 as well.

Can you try the regular update in a browser windor with the same api key?

https://api.thingspeak.com/update.json?api_key=xxxxxxxxxxxxxxxx&field1=10

Also double check your channel ID. I have made that error myself before.

Answer 2

[avner gideobi]

Thank you Vinod and Christopher for your quick reply!

for start, hitting the URL with the right api key works. Also from CURL with POST command.

I am building a big IoT project which the ThingsSpeak is a small part of it. In the project I use modern libraries such as WiFiClientSecure which greatly simplify communication, and eliminate the need to manually implement POST requests.

So, the problem is probably somewhere between the way I implemented it and Thingsspeak.

Would appriciate any help to attempt.

[Vinod]

If you are implementing your own connectivity, I would recommend taking a look at this:

https://github.com/mathworks/thingspeak-arduino

It has an implementation you can use as a starting point for your own.

Answer 3

[avner gideobi]

Thanks again Vinod.

Good suggestion. I started there, unfortunately it dosen't support bulk CSV update, hence I need to do it myself.

[Vinod]

I would look at the response code you are getting to try and troubleshoot the problem. A 401 response usually means that you have an incorrect API key, or it doesn't correspond to the channel you are updating. If you are able to get it working in CURL, then I would compare the CURL request to what is being sent from your Arduino as a starting point.