FPGA vs MCU vs MPU: Which One Should You Use?

FPGA vs MCU vs MPU: Which One Should You Use?

If you’re building an electronic product, one of the biggest architecture decisions is choosing the “brain” type:
• MCU (Microcontroller): best for control + sensors + simple connectivity
• MPU (Microprocessor): best for Linux, UI, complex apps, heavy networking
• FPGA: best for custom high-speed hardware logic and real-time parallel processing

Choosing wrong costs you months: you either run out of performance, burn power, increase BOM cost, or create a software/firmware nightmare.

This guide gives clear decision rules and real-world examples.

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What each one really is

MCU (Microcontroller Unit)

An MCU is an all-in-one chip that includes CPU + Flash + RAM + peripherals (ADC, timers, UART, SPI, I2C, etc.). It usually runs bare-metal code or a small RTOS.

Best at:
• reading sensors
• controlling motors/relays/LEDs
• low-power battery designs
• simple communications and control loops

Typical power:
• very low, great sleep modes

Typical software:
• C/C++ firmware, RTOS optional

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MPU (Microprocessor Unit)

An MPU is more like a “small computer CPU.” It usually needs external RAM, external Flash storage, and runs an OS (often Linux).

Best at:
• UI with graphics (touchscreen)
• networking-heavy systems (Wi-Fi/Ethernet + services)
• running complex apps, databases, AI-lite tasks
• faster development using Linux ecosystem

Typical power:
• higher than MCU

Typical software:
• Linux, drivers, Python/Go/Node apps, etc.

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FPGA (Field-Programmable Gate Array)

An FPGA is hardware you can configure to become custom digital logic. It’s parallel by nature and can do high-speed processing with deterministic timing.

Best at:
• high-speed data capture and processing
• custom interfaces/protocol bridging
• precise timing, parallel pipelines
• “hardware acceleration” for specific tasks

Typical power:
• can be moderate to high (depends heavily on design)

Typical development:
• HDL (Verilog/VHDL) or higher-level tools
• hardware verification effort is real

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Quick decision rules (simple and practical)

Choose an MCU when:
• You need control logic, sensors, PWM, ADC, low power
• You do not need Linux
• Your UI is simple (LEDs, small segment display, basic LCD)
• BOM cost must be low and stable
• Real-time response is important but not ultra-high bandwidth

Examples:
• smart plugs, thermostats, controllers, handheld devices
• battery sensors, BLE tags
• motor controllers, simple industrial nodes

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Choose an MPU when:
• You need a full OS + networking stack + fast feature development
• You need a rich UI (touchscreen, graphics)
• You need high-level software (web server, OTA, logging, remote management)
• You can accept higher power and more complex hardware

Examples:
• smart displays, gateways, IPC cameras, POS terminals
• IoT hubs, edge devices
• products that run web UI + cloud services

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Choose an FPGA when:
• You need high-speed parallel processing or custom timing
• Your problem is “hardware-defined” (not just software)
• You need deterministic latency at high data rates
• Standard chips cannot meet your interface/protocol needs

Examples:
• high-speed video processing
• software-defined radio (SDR)
• custom sensor fusion at high throughput
• protocol bridging at high speed (and unusual interfaces)

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Comparison that matters (cost, time, risk)

1) BOM cost
• MCU: usually lowest total cost
• MPU: higher (external RAM/Flash/PMIC often needed)
• FPGA: can be highest, plus supporting power rails and memory

2) Development speed
• MCU: fast for control firmware, slower for complex UI/network apps
• MPU: fast for feature-rich products (Linux tools, libraries)
• FPGA: slowest (verification, hardware thinking, toolchains)

3) Power consumption
• MCU: best for low power and long battery life
• MPU: higher, often needs heat/power design
• FPGA: varies but can be high, especially at high clocks

4) Real-time determinism
• MCU: good (especially with RTOS)
• MPU: weaker (Linux is not deterministic unless using RT patches)
• FPGA: best (true deterministic parallel logic)

5) Flexibility / updates
• MCU: firmware updates are easy, limited compute
• MPU: most flexible, like updating software on a computer
• FPGA: reconfigurable, but validation and safety matter a lot

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The “hybrid” approach (very common in real products)

Many products combine chips:

MCU + MPU
• MCU handles real-time control and safety
• MPU runs Linux/UI/network features

Example:
• industrial HMI: Linux for UI + small MCU for motor/relay control

MCU + FPGA
• FPGA handles high-speed acquisition/processing
• MCU handles control, configuration, communication

Example:
• data acquisition system: FPGA streams data + MCU manages settings

MPU + FPGA
• FPGA accelerates processing
• MPU handles software stack, UI, storage, networking

Example:
• video analytics: FPGA pre-processes frames + MPU runs AI pipeline

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Common mistakes (what causes wasted time)
• Using an MPU when an MCU is enough → higher cost, power, complexity
• Using an MCU for a Linux-like workload → painful development, unstable features
• Choosing FPGA for “performance” without a clear hardware need → long dev cycle
• Underestimating software stack costs (drivers, OTA, security)
• Ignoring supply chain availability (MPU/FPGA can have longer lead times)

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A practical “which should I pick?” checklist

Answer these questions:
1. Do you need Linux, a touchscreen UI, or complex networking apps?
→ If yes, lean MPU.
2. Do you need ultra-low power or long battery life?
→ If yes, lean MCU.
3. Do you need deterministic timing at very high bandwidth or custom interfaces?
→ If yes, consider FPGA.
4. Is your product mostly control + sensors + communication?
→ Usually MCU.
5. Do you need to ship fast with lots of software features?
→ MPU may reduce software time (even if hardware is harder).