This library provides access to ThingsBoard platform over MQTT protocol.
The SDK comes with a number of example sketches. See File > Examples > ThingsBoard within the Arduino application. Please review the complete guide for ESP32 Pico Kit GPIO control and DHT22 sensor monitoring available here.
ThingsBoard SDK can be installed directly from the Arduino Library manager. Following dependencies must be installed, too:
- MQTT PubSub Client — for interacting with MQTT.
- ArduinoJSON — for dealing with JSON files.
- Arduino Http Client — for interacting with ThingsBoard using HTTP.
The buffer size for the serialized JSON is fixed to 64 bytes. The SDK will reject a data, if there is more data to be sent. Respective logs in the "Serial Monitor" window will indicate the condition:
[TB] too small buffer for JSON data
If that's a case, the buffer size for serialization should be increased. To do so, ThingsBoardSized class can be used in place of ThingsBoard as illustrated below:
// For the sake of example
WiFiEspClient espClient;
// The SDK setup with 64 bytes for JSON buffer
// ThingsBoard tb(espClient);
// The SDK setup with 128 bytes for JSON buffer
ThingsBoardSized<128> tb(espClient);A buffer allocated internally by ArduinoJson library is fixed and is capable for processing not more than 8 fields. If you are trying to send more than that, you will get an error in the "Serial Monitor" window of the Arduino IDE:
[TB] too much JSON fields passed
The solution is to use ThingsBoardSized class instead of ThingsBoard. Note that the serialized JSON buffer size must be specified explicitly, as described here.
// For the sake of example
WiFiEspClient espClient;
// The SDK setup with 8 fields for JSON object
// ThingsBoard tb(espClient);
// The SDK setup with 128 bytes for JSON payload and 32 fields for JSON object.
ThingsBoardSized<128, 32> tb(espClient);To use your own logger you have to create a class and pass it as third parameter Logger to your ThingsBoardSized class instance.
For example:
class CustomLogger {
public:
static void log(const char *error) {
Serial.print("[Custom Logger] ");
Serial.println(error);
}
};Your class must have method log with the same prototype as in the example. It will be called if some error occurs.
After that, you can use it in place of regular ThingsBoard class. Note that the serialized JSON buffer size must be specified explicitly, as described here.
// For the sake of example
WiFiEspClient espClient;
// The SDK setup with 8 fields for JSON object
// ThingsBoard tb(espClient);
// The SDK setup with 128 bytes for JSON payload and 32 fields for JSON object.
ThingsBoardSized<128, 32, CustomLogger> tb(espClient);You are welcomed in our issues and Q&A forum.
This code is released under the MIT License.