First not so significant part solved.
With the below code, in loop(), I first establish a WLAN router and then an MQTT broker connection. The CoolTerm serial output shows the first two lines repeated. Why is this?
23:10:39.096 →
23:10:39.096 → Trying to connect to WLAN router
23:10:40.757 →
23:10:41.536 → Trying to connect to WLAN router
23:10:51.635 → 3
23:10:51.742 → Connection to WLAN router successful
23:10:51.843 → Trying to connect to Adafruit IO
23:10:55.303 → Connection to Adafruit IO successful
The somewhat more concerning problem is that when I switch the WLAN router off and on again a few minutes later, I sometimes do get a WLAN re-connection, but sometimes not. I am publishing every 30 seconds, not subscribing. What should I change to achieve better reliability?
include <SPI.h>
#include <WiFiNINA.h> // Adafruit's WiFiNINA fork, use version 1.4.0
#include "Adafruit_MQTT.h"
#include "Adafruit_MQTT_Client.h"
// Variables...
int status = WL_IDLE_STATUS; // Necessary at start
// Instanced objects...
void setup()
{
// CoolTerm output only needed for debugging
Serial.begin(9600);
while (!Serial); Serial.println();
// Override default pins with the AirLift's breakout board pins
WiFi.setPins(SPIWIFI_SS, SPIWIFI_ACK, ESP32_RESET, ESP32_GPIO0, &SPIWIFI);
// Indicate there is no WLAN router connection yet; GRB colour order!
WiFi.setLEDs(0, 255, 0);
delay(2000);
}
void loop()
{
connectToWLAN();
connectToMQTT();
// Sensor reading and MQTT publishing...
}
void connectToWLAN()
{
if (WiFi.status() == WL_NO_MODULE)
{
Serial.println("Connection to AirLift FeatherWing WLAN module failed");
// Indicate there is a WLAN module malfunction
WiFi.setLEDs(0, 255, 255);
while (true);
}
// Return to loop() if already connected to WLAN router
if (WiFi.status() == WL_CONNECTED)
{
return;
}
Serial.println("Trying to connect to WLAN router");
// Indicate there is no WLAN router connection
WiFi.setLEDs(96, 255, 0);
do
{
status = WiFi.begin(WLAN_SSID, WLAN_PASS);
// WL_IDLE_STATUS = 0
// WL_NO_SSID_AVAIL = 1
// WL_SCAN_COMPLETED = 2
// WL_CONNECTED = 3
// WL_CONNECT_FAILED = 4
// WL_CONNECTION_LOST = 5
// WL_DISCONNECTED = 6
Serial.println(WiFi.status());
delay(100);
}
while (status != WL_CONNECTED);
Serial.println("Connection to WLAN router successful");
// Indicate that the WLAN router connection was established
WiFi.setLEDs(192, 255, 0);
delay(1000);
}
void connectToMQTT()
{
// Return to loop() if already connected to MQTT broker
if (mqtt.connected())
{
return;
}
Serial.println("Trying to connect to Adafruit IO");
// Stores a printable string version of the error code returned by
// connect()
int8_t MQTTerrorString;
// In case the error code is not 0, meaning successful connection
while ((MQTTerrorString = mqtt.connect()) != 0)
{
// Print an error message matching the error code
switch (MQTTerrorString)
{
case 1: Serial.println("Wrong protocol"); break;
case 2: Serial.println("ID rejected"); break;
case 3: Serial.println("Server unavailable"); break;
case 4: Serial.println("Bad username/password"); break;
case 5: Serial.println("Not authenticated"); break;
case 6: Serial.println("Failed to subscribe"); break;
default: Serial.println("Connection failed"); break;
}
// And in case of an error
if (MQTTerrorString >= 0)
{
// Send a MQTT disconnect packet and break the connection
mqtt.disconnect();
// And indicate that the connection failed
WiFi.setLEDs(255, 0, 255);
Serial.println("Retry to connect");
// Wait n seconds before returning to loop() and trying again
delay(3000);
}
}
// Indicate that the MQTT broker connection was established
WiFi.setLEDs(255, 0, 0);
delay(1000);
Serial.println("Connection to Adafruit IO successful");
}