MCU Hardware
Microcontroller Platforms
The canonical TinyML teaching board. Packs a Cortex-M4 (64 MHz, 256 KB RAM, 1 MB Flash) with 9-axis IMU, PDM microphone, temperature, humidity, pressure, and colour/proximity sensors. Supported out-of-the-box by TFLite Micro and Edge Impulse.
- CPU: nRF52840 Cortex-M4 @ 64 MHz
- RAM: 256 KB | Flash: 1 MB
- Built-in: IMU, mic, env sensors, colour sensor
- BLE 5.0 radio
- Edge Impulse first-class support
Espressif's AI-oriented MCU: dual-core Xtensa LX7 at 240 MHz with vector extensions for INT8 ML, up to 8 MB PSRAM, Wi-Fi + BLE, and a USB OTG. Excellent price-performance for camera + audio TinyML at ~$3/unit.
- CPU: dual Xtensa LX7 @ 240 MHz
- RAM: 512 KB SRAM + up to 8 MB PSRAM
- Flash: up to 16 MB
- Wi-Fi 802.11 b/g/n + BLE 5.0
- AI vector instructions (INT8 SIMD)
STMicroelectronics' broad MCU range from Cortex-M0 (ultra-low-power) to M7 (1 MB RAM, 480 MHz). STM32Cube.AI and STEdgeAI tools convert ONNX/TFLite models and optimise for STM32 targets with cycle-accurate profiling.
- Range: M0+ (16 KB RAM) to M7 (1 MB RAM)
- STM32Cube.AI (free model converter)
- X-CUBE-AI integration for inference
- Large ecosystem: HAL, FreeRTOS, Zephyr
- STM32N6 adds dedicated NPU
ARM Cortex-M4 with BLE 5.0/Bluetooth Mesh/Thread/Zigbee. Industry standard for wearables and IoT. 256 KB RAM supports modest neural nets for keyword spotting and gesture recognition with duty-cycled BLE data transmission.
- CPU: Cortex-M4 @ 64 MHz with FPU
- RAM: 256 KB | Flash: 1 MB
- BLE 5.0, Bluetooth Mesh, Thread, Zigbee
- Ultra-low power modes (1.5 µA sleep)
- Arm TrustZone security
TinyML Hardware Comparison
| Board / MCU | Core | Flash | RAM | Clock | TinyML Frameworks | Best For |
|---|---|---|---|---|---|---|
| Arduino Nano 33 BLE Sense | Cortex-M4 | 1 MB | 256 KB | 64 MHz | TFLite Micro, Edge Impulse | Prototyping, education |
| ESP32-S3 | Xtensa LX7 (dual) | Up to 16 MB | 512 KB + 8 MB PSRAM | 240 MHz | TFLite Micro, Edge Impulse | Wi-Fi/BT, camera, audio |
| STM32H7 series | Cortex-M7 | 2 MB | 1 MB | 480 MHz | TFLite Micro, STM32Cube.AI | High-perf industrial ML |
| Nordic nRF52840 | Cortex-M4 | 1 MB | 256 KB | 64 MHz | TFLite Micro, Edge Impulse | BLE wearables, keyword detect |
| Raspberry Pi RP2040 | Cortex-M0+ (dual) | External (2–16 MB) | 264 KB | 133 MHz | TFLite Micro, microTVM | Cost-sensitive prototyping |
| MAX78000 | Cortex-M4 + CNN HW | 512 KB | 128 KB | 100 MHz | Maxim AI SDK | Ultra-low power vision |
| GreenWaves GAP9 | RISC-V (10-core) | External | 1.7 MB L2 | 370 MHz | GAPflow / ONNX | Audio & sensor fusion |
Common Sensors for TinyML
Most common TinyML sensor. 3-axis accelerometer + gyroscope provides motion data for gesture recognition, fall detection, activity classification, and vibration-based anomaly detection. Low power: typically 10–300 µA.
- Common: LSM6DS3, MPU6050, ICM-42688
- Output: 6-DoF at up to 6.4 kHz
- I2C / SPI interface
- 10–300 µA active current
- Use case: gesture, activity, vibration
Pulse-Density Modulation microphones (e.g., MP34DT05) enable keyword spotting and sound classification on MCUs. Low-cost, low-power, and directly digitally interfaced — no ADC needed.
- Common: MP34DT05, SPH0641LM4H
- 16-bit audio at 16–32 kHz
- PDM or I2S output
- Active current: ~650 µA
- Use case: keyword spotting, sound events
Low-resolution CMOS sensors (e.g., OV2640, HM01B0) enable person detection and simple vision tasks on MCUs. The HM01B0 QVGA sensor consumes under 2 mW — enabling always-on vision on battery devices.
- HM01B0: 320×240, <2 mW always-on
- OV2640: 2 MP, widely available
- DVCP / SPI / parallel interface
- QQVGA (160×120) fits in 256 KB RAM
- Use case: person detect, face detect
Dedicated AI Accelerator MCUs
| Device | Vendor | Accelerator | Peak TOPS | Power | Notes |
|---|---|---|---|---|---|
| MAX78000 | Analog Devices (Maxim) | CNN hardware engine | ~0.5 TOPS | <1 mW inference | Ultra-low power, fixed CNN topology |
| STM32N6 (NPU) | STMicroelectronics | Neural Processing Unit | 600 GOPs | ~10 mW | STM32 ecosystem, STEdgeAI |
| Syntiant NDP120 | Syntiant | Deep Learning Processor | Custom | <140 µW | Always-on audio, keyword spotting |
| Ambiq Apollo510 | Ambiq | Neural Spot (SPOT) | Custom | <1 mW | Wearable health AI |
| GreenWaves GAP9 | GreenWaves Technologies | 10-core RISC-V cluster | ~0.25 TOPS | ~20 mW | Audio + sensor fusion |
