An Arduino wrapper for PubSubClient that manages MQTT connectivity. The wrapper functions make use of non-blocking connection checking.
To use the library, you will need to create a file, wifi_credentials.h, that declares:
const char* ssid = "WPI-Open";
const char* password = "";
//---- HiveMQ Cloud Broker settings
const char* mqtt_server = "....s1.eu.hivemq.cloud"; // from your HiveMQ account
const char* mqtt_username = ""; // from your HiveMQ account
const char* mqtt_password = ""; // from your HiveMQ account
const int mqtt_port = 8883;
// HiveMQ Cloud Let's Encrypt CA certificate
static const char *root_ca PROGMEM = R"EOF(
-----BEGIN CERTIFICATE-----
MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAw
TzELMAkGA1UEBhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2Vh
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oyi3B43njTOQ5yOf+1CceWxG1bQVs5ZufpsMljq4Ui0/1lvh+wjChP4kqKOJ2qxq
4RgqsahDYVvTH9w7jXbyLeiNdd8XM2w9U/t7y0Ff/9yi0GE44Za4rF2LN9d11TPA
mRGunUHBcnWEvgJBQl9nJEiU0Zsnvgc/ubhPgXRR4Xq37Z0j4r7g1SgEEzwxA57d
emyPxgcYxn/eR44/KJ4EBs+lVDR3veyJm+kXQ99b21/+jh5Xos1AnX5iItreGCc=
-----END CERTIFICATE-----
)EOF";
The wifi_credentials.h file can live wherever you want, so long as it can be found by the compiler. If you put it in the src folder of your project, be sure to add it to your .gitignore file. Better is to put it in a local directory on your machine and point to it using lib_extra_dirs. You will need to edit platformio.ini in the example(s) to point to the correct directory.
The examples demonstrate the workflow shown below. Call sendMessage(topic, message) from a Romi/Leonardo to send a message. The example code for the ESP32 will prepend the team name to the topic. See the readme files in the example folders for additional chip-specific information.
The ESP32 example will subscribe to all messages on the root topic and pass messages on to the Romi. It is up to the user to create a means of handling messages received. The figure below shows a teamN topic -- ignore that.
If your Romi/Leonardo is running at 5V (the default), you must use a level shifter to drop the voltage from the TX on the Romi to the RX on the ESP32. See the readme's in the specific examples for more information.
