Connect Your ESP32 | Arduino IDE

Add ESP32 board support

If you've never flashed an ESP32 from the Arduino IDE before, you need to add Espressif's board package first.

In the Arduino IDE, open File → Preferences and add this URL to the Additional Board Manager URLs field:

https://espressif.github.io/arduino-esp32/package_esp32_index.json

Then open Tools → Board → Boards Manager, search for esp32, and install the esp32 package by Espressif Systems.

Once it finishes, select your board under Tools → Board → esp32. If you're not sure, ESP32 Dev Module is a safe default.

Install PubSubClient

Open Tools → Manage Libraries, search for PubSubClient, and install the one by Nick O'Leary (version 2.8 or later).

Install the Minimalist SDK

Download the SDK and unzip it. You'll get three folders: device_id, wifi_tools, and mqtt.

Drop all three folders into your Arduino libraries directory:

macOS / Linux:  ~/Documents/Arduino/libraries/
Windows:        Documents\Arduino\libraries\

When you're done it should look like this:

Arduino/
└── libraries/
    ├── device_id/
    │   ├── device_id.h
    │   └── device_id.cpp
    ├── wifi_tools/
    │   ├── wifi_tools.h
    │   └── wifi_tools.cpp
    └── mqtt/
        ├── mqtt.h
        └── mqtt.cpp

Restart the Arduino IDE so it picks up the new libraries.

Create your sketch

In the Arduino IDE, File → New Sketch, then File → Save As — name it ohioiot_connect. Arduino will create a folder with a matching .ino file inside.

Now add a second file to the sketch. In the tab bar, click the small down-arrow and choose New Tab. Name it credentials.h. Paste these values from the Settings page in the dashboard:

#define WIFI_SSID   "YourWiFiName"
#define WIFI_PASS   "YourWiFiPassword"

#define MQTT_HOST   "mqtt.ohioiot.com"
#define MQTT_PORT   8883
#define MQTT_USER   "larry"
#define MQTT_PASS   "your_mqtt_password"

Port 8883 is the TLS port. Don't change it.

The sketch

Switch back to the main ohioiot_connect.ino tab and paste this:

#include "credentials.h"
#include <device_id.h>
#include <wifi_tools.h>
#include <mqtt.h>

char DEVICE_ID[9];

void setup() {

    Serial.begin(115200);
    Serial.println("\n\n  booting...\n");

    device_id.get_or_set(DEVICE_ID);

    wifi_tools.begin(WIFI_SSID, WIFI_PASS);

    mqtt.setup(MQTT_HOST, MQTT_PORT, DEVICE_ID, MQTT_USER, MQTT_PASS);
}

void loop() {

    if (wifi_tools.is_connected) {
        mqtt.maintain();
    } else {
        wifi_tools.reconnect();
        mqtt.report_disconnect();
    }
}

The SDK headers use angle brackets (<mqtt.h>) because they live in the Arduino libraries folder. credentials.h uses quotes because it's part of your sketch.

Flash and watch

Plug in your ESP32, pick the correct port under Tools → Port, and click the Upload button (→ arrow) in the toolbar.

When it finishes uploading, open Tools → Serial Monitor and set the baud rate to 115200. You should see:

  booting...

	existing deviceID: a8f3k2m1

	wifi connecting...
	wifi connected...

	mqtt connecting...
	mqtt connected...