The Embedded C SDK, the newest addition to the Azure SDKs family, was designed to allow embedded IoT devices to leverage Azure services like device to cloud telemetry, cloud to device messages, direct methods, device twin, device provisioning, and IoT plug and play, all while maintaining a minimal footprint. You will have full control over memory allocation and the flexibility to bring your own MQTT client, TLS, and Socket layers.
Check out the new Embedded C SDK on GitHub