Azure RTOS Pricing and Features: Embedded Real-Time Operating System

Azure RTOS (Eclipse ThreadX): Pricing and Features Guide

Azure RTOS is Microsoft's embedded real-time operating system for IoT devices. In 2023, Microsoft donated Azure RTOS to the Eclipse Foundation, where it continues as Eclipse ThreadX. The core ThreadX kernel (RTOS) and middleware components remain free and open source. EPC Group helps enterprises integrate Azure RTOS / Eclipse ThreadX into IoT device firmware for industrial, healthcare, and defense applications. 29 years of Microsoft experience.

Key facts

• Azure RTOS was renamed to Eclipse ThreadX in 2023 after donation to the Eclipse Foundation.
• Kernel footprint: as small as 2 KB ROM, 1 KB RAM — suitable for deeply constrained microcontrollers.
• Deterministic scheduling: guarantees worst-case response times required for real-time control.
• Safety certifications: IEC 61508 (industrial), IEC 62304 (medical), ISO 26262 (automotive).
• License: open source under MIT license — free for commercial use.
• EPC Group: 29 years Microsoft consulting, 10,000+ enterprise deployments.

What is Azure RTOS / Eclipse ThreadX?

Azure RTOS is a real-time operating system (RTOS) for microcontrollers and embedded IoT devices. It is now called Eclipse ThreadX after Microsoft donated it to the Eclipse Foundation in 2023.

Unlike Linux-based embedded solutions, Azure RTOS has an extremely small memory footprint. The kernel starts at 2 KB ROM and 1 KB RAM. Boot times are measured in microseconds.

Deterministic scheduling guarantees worst-case response times. This is required for real-time control systems where a missed deadline can cause hardware damage or safety incidents.

Azure RTOS Components

Azure RTOS / Eclipse ThreadX is a family of embedded middleware components that work together:

• ThreadX kernel — The RTOS core. Priority-based preemptive scheduling with preemption-threshold. Extremely small footprint.
• NetX Duo — TCP/IP network stack. Supports IPv4, IPv6, MQTT, HTTP, TLS/SSL, and other protocols for IoT connectivity.
• FileX — FAT-compatible file system for embedded storage (SD cards, flash memory).
• USBX — USB device and host stack. Supports USB device classes (CDC, HID, MSC).
• GUIX — Embedded GUI framework for touchscreen and display-based IoT devices.
• LevelX — NOR and NAND flash wear-leveling driver for file system durability.

Supported MCU Families

Azure RTOS / Eclipse ThreadX supports a broad range of microcontroller architectures:

• ARM Cortex-M — M0, M0+, M3, M4, M7, M23, M33, M55 (the most common IoT MCU family)
• ARM Cortex-A — Application processors for higher-performance embedded Linux alternatives
• RISC-V — Open-source ISA gaining adoption in industrial IoT
• Renesas RX/RA — Common in Japanese industrial and automotive applications
• Microchip PIC32/SAM — Common in industrial control and medical devices
• NXP i.MX RT — Crossover MCU family for higher-performance edge applications
• STMicroelectronics STM32 — The most widely used ARM Cortex-M MCU family globally

Azure RTOS vs. FreeRTOS

Both are popular open-source RTOSes for embedded IoT. Key differences:

| Feature | Azure RTOS / ThreadX | FreeRTOS | |---|---|---| | Kernel ROM footprint | 2 KB | ~5–10 KB | | Scheduling feature | Preemption-threshold (unique) | Standard priority preemption | | Safety certifications | IEC 61508, IEC 62304, ISO 26262 | Safety-critical version via FreeRTOS-MPU | | Middleware ecosystem | ThreadX family (NetX, FileX, USBX, GUIX) | AWS ecosystem (coreMQTT, FreeRTOS+TCP) | | License | MIT (open source) | MIT (open source) | | Cloud connectivity | Azure IoT Hub via NetX Duo | AWS IoT Core preferred | | Support | Eclipse Foundation community | Amazon + community |

Safety Certifications

Azure RTOS / Eclipse ThreadX holds pre-certified safety certifications for three industries:

• IEC 61508 (SIL 4) — Industrial functional safety. Covers industrial control systems, drives, and process automation.
• IEC 62304 (Class A, B, C) — Medical device software. Required for FDA-cleared and CE-marked medical devices with embedded software.
• ISO 26262 (ASIL D) — Automotive functional safety. Required for automotive control units and ADAS systems.

Pre-certification reduces the time and cost of obtaining your own safety certification for regulated products. The certification covers the ThreadX kernel — you still need to certify your application code separately.

Azure IoT Hub Integration

Azure RTOS / ThreadX connects to Azure IoT Hub through NetX Duo and the Azure IoT C SDK. This enables cloud-connected IoT device scenarios:

• Device-to-cloud telemetry (sensor data to Azure IoT Hub)
• Cloud-to-device commands (remote control from Azure)
• Device twin: synchronized device state between the device and Azure
• OTA (over-the-air) firmware updates via Azure Device Update for IoT Hub
• TLS 1.2 encrypted connections via NetX Duo TLS

Frequently asked questions

What is Azure RTOS?

Azure RTOS is Microsoft's embedded real-time operating system for IoT devices. It is now called Eclipse ThreadX after Microsoft donated it to the Eclipse Foundation in 2023. It is open source under the MIT license and free for commercial use.

What is the difference between Azure RTOS and Eclipse ThreadX?

They are the same product under different names. Microsoft developed Azure RTOS (ThreadX kernel + middleware). In 2023, Microsoft donated it to the Eclipse Foundation. It now continues as Eclipse ThreadX under open-source governance.

Is Azure RTOS free?

Yes. Azure RTOS / Eclipse ThreadX is open source under the MIT license. All components (ThreadX, NetX Duo, FileX, USBX, GUIX, LevelX) are free for commercial use without royalties.

What is preemption-threshold scheduling?

Preemption-threshold is a ThreadX-specific scheduling feature. It lets you set a threshold below which a running thread cannot be preempted by other threads, while still allowing higher-priority threads above the threshold to preempt normally. This reduces context-switch overhead without sacrificing real-time responsiveness.

What safety certifications does Azure RTOS / ThreadX have?

IEC 61508 (SIL 4) for industrial, IEC 62304 (Class A/B/C) for medical devices, and ISO 26262 (ASIL D) for automotive. Pre-certification covers the ThreadX kernel. Application code requires separate certification for regulated products.

Integrate Azure RTOS in your IoT product

Talk to an EPC Group embedded and IoT architect about Azure RTOS / Eclipse ThreadX integration with your device firmware and Azure IoT cloud. Call (888) 381-9725 or request a 30-minute discovery call.