MCU Platforms & Chip Families

The chip itself is the first decision. Most decisions downstream (toolchain, RTOS, language, wireless) flow from it. For dev boards see Dev Kits & Boards; for production modules see MCU Modules; for the IDEs / build systems see Arduino & PlatformIO.

Espressif ESP32 family

The dominant Wi-Fi-enabled hobbyist MCU. Cheap, well-documented, huge community, official Rust + IDF + Arduino + MicroPython support.

• ★ ESP32 (classic) — dual-core Xtensa LX6 @ 240 MHz, Wi-Fi 4 + Bluetooth Classic + BLE 4.2. The original 2016 part; still everywhere because it's $2 and works. Use for: Wi-Fi+BT projects where cost matters.
• ★ ESP32-S3 — dual-core Xtensa LX7 @ 240 MHz, Wi-Fi 4 + BLE 5, native USB, vector extensions for AI. The current sweet spot for new hobby/maker projects — fast, USB-OTG built in, lots of GPIO, runs TinyML.
• ESP32-S2 — single-core LX7, Wi-Fi only (no BT), native USB. Niche; S3 superseded it for most uses.
• ★ ESP32-C3 — single-core RISC-V @ 160 MHz, Wi-Fi 4 + BLE 5. The cheap RISC-V option ($1-ish in modules). Great for sensors / smart-plug-class things. First-class Rust support via esp-rs.
• ★ ESP32-C6 — single-core RISC-V @ 160 MHz, Wi-Fi 6 + BLE 5 + 802.15.4 (Thread / Zigbee). The Matter-era ESP32 — what you want for new smart-home work in 2026.
• ESP32-H2 — RISC-V, 802.15.4 only (Thread / Zigbee), BLE 5; no Wi-Fi. Pair with a C6/S3 router or use as a dedicated Thread/Zigbee endpoint.
• ESP32-C5 — newer dual-band (2.4 + 5 GHz) Wi-Fi 6 RISC-V; sampling / early production in 2026.
• ESP32-P4 — high-performance dual-core RISC-V @ 400 MHz, HiFi5 DSP, MIPI-CSI / DSI for cameras and displays, no built-in Wi-Fi (pair with a C6 over SDIO). The "ESP for HMIs and AI cameras" part. Dev kits widely available in 2026.
• ESP8266 / ESP8285 — the original $1 Wi-Fi MCU. Single-core Xtensa, Wi-Fi only. Still fine for ultra-cheap deploy-and-forget switches; for new designs the ESP32-C3 is barely more expensive and far more capable.

All ESP32-* parts: open SDK (Apache 2.0 ESP-IDF), free toolchains, FCC/CE-pre-certified modules from Espressif, second-source from Ai-Thinker / SeeedStudio. No royalties.

Raspberry Pi RP2040 / RP2350

The "I want a clean MCU without wireless baggage" pick.

• ★ RP2040 (Pi Pico, Pico W) — dual-core Cortex-M0+ @ 133 MHz, PIO (programmable IO state machines — the killer feature), 264 KB SRAM, no on-chip flash. Pico W adds Infineon CYW43439 Wi-Fi/BT. Ridiculously well-documented C SDK + first-class MicroPython.
• ★ RP2350 (Pi Pico 2, Pico 2 W) — released 2024, mature in 2026. Dual Cortex-M33 or dual RISC-V Hazard3 cores (switchable!) @ 150 MHz, 520 KB SRAM, Arm TrustZone, FPU, more PIO state machines. Pico 2 W has same CYW43439 radio.
• RP2354 / RP2350B — bigger-pin variants used in third-party boards.

PIO is the standout: bit-banged WS2812, DVI video out, 100 Mbps Ethernet — all in software-defined hardware. Bring it up if someone asks "why not just use STM32."

STMicro STM32

The professional / industrial default. Vast catalog, deep tooling, real RTOS lineage.

• ★ STM32F4 — Cortex-M4F @ 168-216 MHz; the workhorse for motor control, USB, audio. Cheap, abundant.
• ★ STM32H7 — Cortex-M7 @ 480-550 MHz, sometimes dual-core (M7 + M4); high-performance industrial.
• STM32G0 / G4 — newer Cortex-M0+/M4 lines; very price-competitive vs. older F0/F1.
• STM32U5 — ultra-low-power Cortex-M33 with TrustZone; battery-powered IoT.
• STM32WB / WBA — built-in BLE 5 / 802.15.4 (Thread / Zigbee / Matter).
• STM32WL — built-in LoRa transceiver (Semtech SX126x on-die). The single-chip LoRaWAN node.
• STM32MP1 / MP2 — Cortex-A7/A35 + M4/M33; runs Linux + RTOS. Edge gateway class.
• STM32N6 — newer NPU-equipped MCU for on-device ML.

Closed silicon, but ST publishes free HAL / LL libs, free STM32CubeIDE, and the ecosystem is enormous.

Nordic Semiconductor nRF

The BLE specialist. The right call for any battery-powered Bluetooth product.

• ★ nRF52840 — Cortex-M4 @ 64 MHz, BLE 5 + 802.15.4 (Thread / Zigbee / Matter), 1 MB flash. The de-facto BLE chip for years; tons of dev kits and modules.
• ★ nRF52833 / 52832 / 52810 / 52805 — same family, smaller flash/RAM/peripherals; pick by price.
• nRF5340 — dual-core (M33 app + M33 net core); newer flagship; better security; runs Zephyr cleanly.
• nRF54L15 / L05 / L10 — 2024-2025 generation; Cortex-M33 with RISC-V coprocessor, BLE 5.4, lower power, faster crypto. The forward path.
• nRF54H20 — high-end multicore (M33 + RISC-V), more memory, AI-capable.
• nRF9151 / 9161 / 9131 — cellular IoT (LTE-M, NB-IoT, GNSS) SIPs. The "directly to AWS over LTE" parts.
• nRF7002 — Wi-Fi 6 companion IC; pairs with nRF52/53/54 to add Wi-Fi.

Nordic has aggressively standardized on Zephyr as their SDK. nRF Connect SDK = Zephyr + Nordic add-ons.

Microchip AVR / SAM (Arduino classic)

• ATmega328P — the Arduino UNO chip. 8-bit AVR @ 16 MHz, 32 KB flash. Still produced, still used in education, still fine for "blink an LED, read a sensor."
• ATmega2560 — Mega's chip; bigger pin count.
• ATtiny85 / 1614 / 3216 — tiny 8-pin AVRs for "I just need a timer."
• SAMD21 / SAMD51 — Cortex-M0+/M4F; the original CircuitPython chip; Adafruit Feather M0/M4, SparkFun, Seeed all built early boards on these. Largely supplanted by RP2040 in the same niche.
• PIC16 / PIC18 / PIC24 / PIC32 — Microchip's older lines; still huge in industrial automation; not a hobby pick in 2026.

Other parts worth knowing

• Bouffalo Lab BL602 / BL616 / BL618 — RISC-V Wi-Fi/BLE, ESP32-cheap, growing software support but smaller community.
• WCH CH32V003 / CH32V20x / CH32V30x — RISC-V from WCH; CH32V003 is a literal 10-cent MCU with a small but vocal hobbyist following. SDK is rough; community filling gaps.
• Renesas RA / RX / RL78 — industrial; first-class FreeRTOS / Zephyr support.
• NXP i.MX RT — "crossover MCU" Cortex-M7 @ 600+ MHz; Teensy 4.x is built on this.
• Teensy 4.x (PJRC) — i.MX RT1062 @ 600 MHz, USB audio / MIDI superpowered. Closed bootloader but everything else open. The audio / DSP enthusiast favorite.
• Sipeed / Kendryte K210, K230 — RISC-V with NPU; on-device vision; niche.

Pick this if…

• Wi-Fi + BLE on a $2 budget: ESP32 classic or ESP32-C3.
• Modern ESP for new projects: ESP32-S3 (USB + AI), or ESP32-C6 (Wi-Fi 6 + Matter).
• Smart-home Matter device: ESP32-C6 / -H2, or nRF52840 / nRF54.
• Battery-powered BLE product: nRF52840 or nRF54L15.
• No wireless, just clean MCU + cool I/O tricks: RP2040 / RP2350 (PIO!).
• Industrial / motor / serious peripherals: STM32F4 / G4 / H7.
• Cellular IoT: nRF9151 (LTE-M / NB-IoT) or u-blox SARA modules + STM32.
• LoRaWAN node, single chip: STM32WL.
• Audio / DSP / fast USB: Teensy 4.x.
• Educational / 8-bit nostalgia: ATmega328P (Arduino UNO).