Short answer: Choose the microcontroller or SoC of an industrial device in this order: (1) peripherals and interfaces that fit the application without external chips, (2) supply security: longevity programme, a pin-compatible family and a second option, (3) software ecosystem: mature SDK, RTOS support, drivers, security libraries and tooling your team already knows, (4) security features required by the market, such as secure boot, crypto acceleration and a unique ID, (5) power and performance with at least 30 % headroom for the life of the product, and (6) unit price last. A €1 saving on the MCU is erased by one extra component or one firmware month.
The selection framework
| Criterion | What to check | Typical weight |
|---|---|---|
| Peripherals and interfaces | ADC resolution and speed, timers/PWM for motor control, CAN/Ethernet/USB, display, crypto, number of UART/SPI/I2C | 30 % |
| Supply security | Longevity programme (10–15 years), pin-compatible family, active status, franchised availability | 25 % |
| Software ecosystem | SDK quality, RTOS (FreeRTOS/Zephyr/Linux) support, driver maturity, debugger and IDE, community | 20 % |
| Power and performance | Core, clock, RAM/flash with 30 % headroom, sleep currents, wake-up time, temperature grade | 15 % |
| Unit price | Price at your volume, package cost, required external parts | 10 % |
Tier by application
- Sensor nodes and simple control: Cortex-M0+/M4 class (STM32L/G, NXP LPC/Kinetis, Nordic nRF52/nRF54 for BLE, Espressif ESP32 for Wi-Fi).
- Motor control and fast loops: Cortex-M4F/M7 with fast ADCs and advanced timers (STM32G4/H7, NXP i.MX RT, TI C2000).
- Connectivity and security: Cortex-M33 with TrustZone and crypto (STM32U5/H5, NXP LPC55, Nordic nRF54).
- Vision, edge AI, HMI, Linux: Cortex-A SoCs (NXP i.MX 8M family, TI AM62/AM64, ST STM32MP1/MP2), often with an NPU.
Mistakes we see, and their cost
- Choosing on price: a cheaper MCU without CAN or a second ADC adds two chips and layout area, and often costs more overall.
- Ignoring lifecycle: an MCU without a longevity programme forces a port within the product's life.
- No headroom: firmware grows; a device at 90 % flash on release cannot take the security update the market will demand.
- Unfamiliar ecosystem: a new vendor costs a learning curve on every driver and debug session.
- Overlooking security hardware: retrofitting secure boot without hardware support is often impossible.
Key facts
- Most vendors offer longevity programmes guaranteeing 10–15 years of supply; check the part is enrolled.
- Pin-compatible families let you move up or down in memory and speed without a layout change.
- 30 % flash and RAM headroom at release is a practical minimum for a networked product.
- Comtec Labs selects the processor with the customer in stage 2 of the development process and designs the hardware abstraction layer so a port stays a port.
How we make the decision with you
We list the interfaces and loops the device needs, score two or three candidate families against the framework, check supply and pricing at your volume through franchised distribution and prototype on an evaluation board before the schematic is drawn. The result is a documented decision you can defend in five years.
Frequently asked questions
MCU or SoC, what is the difference?
A microcontroller (MCU) runs bare-metal or an RTOS from internal flash with deterministic timing; a system on chip (SoC) runs Linux or Android from external memory with more compute and peripherals such as display and camera interfaces. Control loops favour MCUs; vision, HMI and heavy networking favour SoCs; many products use both.
Should we standardise on one vendor?
Standardising on one or two families reduces tooling and driver effort, as long as each product's choice still passes the lifecycle and peripheral checks.
What about RISC-V?
Viable for specific parts, especially in cost-sensitive and wireless SoCs; ecosystem maturity and longevity programmes still favour ARM for most industrial products.
Can you port our firmware to a new MCU?
Yes. With a hardware abstraction layer the port is drivers and board support; without one, we first introduce the layer and then port.
Ready to reduce PCB surprises?
Comtec Labs offers a full suite of services to streamline your workflow:
PCB design service
PCB prototyping service
PCB component sourcing
PCB component assembly
PCB testing service
PCB repair and modifications
Printed circuit board production
PCB mass production