NirvanaMQTT

A minimal MQTT broker + Arduino library for IoT boards. Publish a sensor reading from an ESP32 or ESP8266 in about five lines, with real TLS and no topic-path bookkeeping.

Quickstart

This is the whole program on the sending side - connect WiFi, trust the broker's certificate, publish:

#include <WiFiClientSecure.h>
#include <NirvanaMQTT.h>
#include <NirvanaMQTT_RootCA.h>

WiFiClientSecure secureClient;
NirvanaMQTT nirvana(secureClient, "demo", "YOUR_ACCOUNT_PASSWORD");

void setup() {
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) delay(250);

  secureClient.setCACert(NIRVANA_ROOT_CA);
  nirvana.begin();
}

void loop() {
  nirvana.loop();
  nirvana.publish("temperature", "25.3");
}

You never type the full topic path. publish("temperature", ...) actually sends to accounts/demo/temperature - the library adds that prefix for you, and the broker enforces that your account can only touch its own accounts/<username>/ namespace.

Install

1. Install the PubSubClient library (by Nick O'Leary) via Arduino IDE's Library Manager - NirvanaMQTT is a thin wrapper around it.
2. Download NirvanaMQTT.zip above, then in the Arduino IDE: Sketch → Include Library → Add .ZIP Library... and select the file.
3. Open File → Examples → NirvanaMQTT for a working ESP32 or ESP8266 sketch.

Getting an account

API reference

Call	What it does
NirvanaMQTT(Client& client, const char* username, const char* password)	Construct with any TLS-capable Client (WiFiClientSecure, BearSSL, etc.) and your account credentials.
begin(host, port)	Connects to the broker. Defaults to api.nirvanatechnologies.in:8883.
loop()	Call every loop() iteration - pumps the connection and auto-reconnects if it drops.
connected()	Returns whether the broker connection is currently up.
publish(topic, payload, retained=false)	Sends payload to accounts/<username>/<topic>.
subscribe(topic)	Subscribes to accounts/<username>/<topic>.
onMessage(callback)	Registers void callback(const char* topic, const char* payload), called for every subscribed topic with the plain (un-prefixed) topic name.

Broker connection details

Host	api.nirvanatechnologies.in
Port	8883 (TLS only - there is no unencrypted port)
Auth	MQTT username/password, one account per set of credentials
Topic scope	accounts/<your-username>/# - your account cannot read or write outside this

Notes

• TLS is required. Boards without enough flash/RAM for TLS (e.g. a bare Arduino Uno) aren't a fit for this service today.
• NirvanaMQTT_RootCA.h ships the broker's actual root CA (ISRG Root X1, valid until 2035), so examples use real certificate verification instead of setInsecure().
• Default max payload is 256 bytes, matching PubSubClient's default packet size. Raise MQTT_MAX_PACKET_SIZE and NIRVANA_MQTT_MAX_PAYLOAD together if you need more.
• ESP32 and ESP8266 set up TLS trust slightly differently at the platform level (setCACert() vs BearSSL's setTrustAnchors()) - that's why there are two examples instead of one.