mqtt Directory Reference

Files
	mqtt.cpp
	MQTT 3.1.1 packet codec (host-testable) + the raw-lwIP / mbedTLS persistent client transport (ESP32 only).
	mqtt.h
	Zero-heap MQTT 3.1.1 publish/subscribe client (DETWS_ENABLE_MQTT).
	mqtt_sn.cpp
	MQTT-SN v1.2 message builder + parser (pure, host-tested).
	mqtt_sn.h
	MQTT-SN v1.2 wire codec (DETWS_ENABLE_MQTT_SN) - zero-heap message builder + parser for MQTT for Sensor Networks, the UDP / non-TCP MQTT variant for constrained, lossy links (topic IDs instead of strings, gateway discovery, sleeping-client keep-alive).