Example for the ESPBackBone library I'm writing

AnalogMqtt.cpp

#include <ESP32BackBone.h>

double value1(0.0);
double value2(0.0);

// Converts the voltage value to 0-100 (used in the display code)
double progress(double inValue)
{
    const double MIN = 0.0;
    const double MAX = 3.3;

    if (inValue < MIN)
    {
        return 0;
    }
    if (inValue > MAX)
    {
        return 100;
    }
    return (inValue - MIN)*100.0/(MAX-MIN);
}

void setup() {

    // "Required" before starting anything else in the backbone.
    espbb::setup();

    // Configure the wifi using build flags (or you can replace these flags with your wifi info, as
    // strings like "ssid", "secret".
    espbb::setWiFi(MY_SSID, MY_WIFI_PASSWORD);

    // Configure OTA.
    espbb::setOta();

    // Configure Mqtt
    espbb::setMqtt(IPAddress(MY_MQTT_ADDRESS), "AnalogMQTT");

    // Test with:
    //    mosquitto_pub -h 10.0.2.50 -t /something -m "123456789012345678901234567890"
    espbb::subscribe(String("/something"),
        [](byte* payload, unsigned int length)
        {
            payload[length] = '\0';
            debugPrintln("[Main]:\tMQTT Rx: " + String((char*)payload));
        });

    // This is a little fishy. Either you have the esp32 with an OLED display, in which case, you
    // would set the DISPLAY_SSD1306 flag, and wouldn't need to check it, or you don't have the
    // display, in which case, you wouldn't write this at all. For the sake of this example, I have
    // written it, and put a flag around it. Sorry, bad examples :(
    #ifdef DISPLAY_SSD1306
        espbb::setDisplay(
            [](SSD1306& display)
            {
                display.setTextAlignment(TEXT_ALIGN_LEFT);

                display.setFont(ArialMT_Plain_16);
                display.drawString(0, 0, String(value1));
                display.drawProgressBar(0, 20, 127, 5, progress(value1));

                display.setFont(ArialMT_Plain_16);
                display.drawString(0, 27, String(value2));
                display.drawProgressBar(0, 46, 127, 5, progress(value2));

            });
    #endif // display
}

void loop() {
    // Update the data used in the display. In this case, I'm doing some analog reading.
    // Keep in mind that ADC2 (pins 8+?) aren't currently readable when you have wifi turned on.
    value1 = static_cast<double>(analogRead(A0)) * 3.3 / 4096.0;
    value2 = static_cast<double>(analogRead(A3)) * 3.3 / 4096.0;

    // Test publishing something.
    // Test with:
    //     mosquitto_sub -h 10.0.2.50 -t /value1
    espbb::publish("/value1", String(value1));

    // This is how I print to the serial (when I have the BBDEBUG flag set).
    //
    // Keep in mind that if you have the display, then the function defined in setup will be used to
    // display these values on the screen, with a progress bar.
    debugPrintln("[Main]:\tSampled 0: " + String(value1) + " 3: " + String(value2));

    // This will slow down the loop(), This will sleep for 10 seconds, so the loop will run a little
    // slower than 10 seconds.
    vTaskDelay(10 * 1000 / portTICK_PERIOD_MS); // pause this task for 10 seconds.
}