MKR Wifi 1010 stops transmitting after a while

Hardware MKR Family MKRWIFI1010
1

My current project consists of a MKR 1010 with a DHT11 sensor that sends its readings to an Airtable by posting the data to the its API endpoint. For a while it worked like magic, but when I left it on overnight, I could see in the logs that it had stopped working. The orange light was also blinking. Tapping reset gets it working again.

My code's posted below (full Airtable URL remove so I don't expose the API key). I've used chunks of things posted online since there are a few threads about this same problem, usually with different solutions.

#include <WiFiNINA.h>
#include <SPI.h>
#include <ArduinoJson.h>
#include "arduino_secrets.h"
#include <DHT.h>

#define DHTPIN 7 // DHT
#define DHTTYPE DHT11 // DHT
DHT dht(DHTPIN, DHTTYPE); // DHT

char ssid[] = SECRET_SSID;
char pass[] = SECRET_PASS;
char server[] = "api.airtable.com";

int status = WL_IDLE_STATUS;
WiFiSSLClient client;
bool wifiBegun(false);

void setup() {

  dht.begin();
  Serial.begin(9600);
  delay(1000);

  if (WiFi.status() == WL_NO_MODULE) { // Check for wifi module
    Serial.println("Communication with WiFi module failed!");
    while (true);
  }
 
}

void loop() {

  if (!wifiBegun) {
    WiFi.begin(ssid, pass);
    delay(250); // acceptable freeze for this props (otherwise use PropsAction for async-like behavior)
    if (WiFi.status() == WL_CONNECTED) {
      wifiBegun = true;
      Serial.println("Connected to Wifi.");
    } else {
      WiFi.end();
    }
  } else if (wifiBegun && WiFi.status() != WL_CONNECTED) {
    WiFi.end();
    wifiBegun = false;
  }

  while (client.available()) {
    char c = client.read();
    Serial.write(c);
  }

  float tmp = dht.readTemperature();
  float hmd = dht.readHumidity();
  float hic = dht.computeHeatIndex(tmp, hmd, false);
  
  if (client.connect(server, 443)) {
    Serial.println("Connected to server.");

    StaticJsonDocument<200> doc;
    JsonObject reading  = doc.createNestedObject("fields");
    reading["Temperature"] = tmp;
    reading["Humidity"] = hmd;
    reading["Heat Index"] = hic;
  
    Serial.print(F("Sending: "));
    serializeJson(doc, Serial);
    Serial.println();
   
    Serial.println("Sending data...");
    client.println("POST /v0/URLREMOVED HTTP/1.1");
    client.println("Host: api.airtable.com");
    client.println("Content-Type: application/json");
    client.println("Authorization: Bearer KEYREMOVED");
    client.print("Content-Length: ");
    client.println(measureJsonPretty(doc));
    client.println();
    serializeJsonPretty(doc, client);
    client.println("Closed the connection");
    client.println();
    client.stop();
    Serial.println("Data sent successfully!");
  }
    else {
    // if you couldn't make a connection:
    Serial.println("Connection failed");
  }
  Serial.println("Stopping now.");
  delay(60000);
}
1 Like
2

Your issue is likely that WiFi.status() is unreliable. It works OK when you start a WiFi connection, but it does not reliably detect disconnects from the WiFi network.

I found the best solution is to check at the application layer whether you still can send or receive information and then reset the WiFi connection. You can find some examples in the forum. For instance, in reply #30 in the following post

https://forum.arduino.cc/index.php?topic=664834.30

I wrote the example for the Arduino Nano 33 IoT which is a smaller variant of your board.

I have used this state machine type on boards with different WiFi modules and run tests over many months. All the boards reconnect reliably multiple times a day.

2 Likes