⚙️ STM32H747 Dual-Core Architecture
Balancing Real-Time Control and High-Speed Computing
The STM32H747, used in the Arduino Portenta H7, is built on a dual-core design — pairing a Cortex-M7 for high-performance processing with a Cortex-M4 for real-time control.
Together, these two cores form a flexible, energy-efficient system where each processor specializes in a specific role — the M7 handles complex computations and multitasking, while the M4 takes care of timing-critical or peripheral control.
This architecture is what allows boards like the Portenta H7 to behave both like a fast embedded computer and a precise industrial controller — all in one.
🧠 How It Works
The STM32H747 uses a heterogeneous dual-core architecture with shared memory and communication channels between the M7 and M4.
Division of Tasks
| Core | Clock Speed | Role / Specialty | Typical Tasks |
|---|---|---|---|
| Cortex-M7 | Up to 480 MHz | High-performance processor | AI tasks, data handling, display, communications |
| Cortex-M4 | Up to 240 MHz | Real-time control core | Sensor I/O, motor control, timing-critical loops |
Both cores have access to shared peripherals and memory, but can also run independent code. Developers can assign tasks depending on timing and performance needs.
🔄 Communication Between Cores
The two cores use inter-processor communication (IPC) to exchange data and synchronize events.
Typical communication methods include:
- Shared RAM regions for passing variables or buffers.
- Mailboxes and semaphores for event signaling.
- Hardware interrupts to wake or notify the other core.
- Task separation via RTOS (FreeRTOS or Mbed OS) to coordinate scheduling.
In the Arduino Portenta H7, the M7 typically runs the Arduino environment, while the M4 can be used for real-time extensions or custom firmware modules.
⚙️ Memory and Resource Sharing
The STM32H747 includes Tightly Coupled Memories (TCMs) for each core and shared SRAM for cooperative data handling.
| Memory Type | Access | Purpose |
|---|---|---|
| TCM (ITCM/DTCM) | Dedicated to M7 | High-speed access for code and data |
| AXI SRAM | Shared | Inter-core communication and large data buffers |
| AHB SRAM | Shared | Peripheral data handling |
| Flash Memory | Shared | Code and firmware storage |
This structure ensures deterministic performance for the M4 and fast throughput for the M7 — crucial for applications like control systems and signal processing.
💡 Advantages of Dual-Core Design
- Real-time + high-level capability: Each core is optimized for a different workload.
- Energy efficiency: One core can enter low-power mode while the other runs.
- Improved responsiveness: Real-time tasks remain stable even during heavy computation.
- Parallel development: Each core can be programmed independently.
- Flexibility for IoT and AI: Ideal for multitasking and sensor fusion.
The dual-core STM32H747 design is like having a control room and a powerhouse on the same chip — both working together for precision and performance.
🧩 Common Use Scenarios
- Industrial automation: M4 controls actuators; M7 handles supervisory logic.
- Machine vision: M7 runs AI inference; M4 manages camera timing.
- Audio and signal processing: M7 processes data; M4 manages streaming.
- IoT hubs: M7 runs networking stacks; M4 manages sensors.
This balance allows the STM32H747 to fit equally well in real-time systems and AI-enhanced IoT devices.