Microcontroller Comparison — core, clock, flash and RAM

Filterable comparison of common microcontrollers by core, clock, flash, RAM and peripherals — with which ones you can emulate in Chiprun.

Example: 13 microcontrollers, 4 of which Chiprun can emulate.

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Parts shown

Emulated in Chiprun: 4
Fastest clock: FE310-G002 (320 MHz)
Most RAM: ESP32 (520 KB)

Flash marked 'external' means the part has no internal program flash and boots from a separate SPI chip — usual for RP2040 and Espressif designs, and it changes both your BOM and your boot time.
4 of these can be emulated in Chiprun, which lets an agent run firmware on them without physical hardware.

Comparison

Part	Vendor	Core	Clock	Flash	RAM	Chiprun	Notes
ATmega2560	Microchip	AVR 8-bit	16 MHz	256 KB	8 KB	—	Arduino Mega. Chosen for its pin count more than its speed.
ATmega328P	Microchip	AVR 8-bit	20 MHz	32 KB	2 KB	—	The Arduino Uno chip. Enormous community, ageing silicon.
ATtiny85	Microchip	AVR 8-bit	20 MHz	8 KB	0.5 KB	—	8 pins. The smallest part people still build real things with.
ESP32	Espressif	Dual Xtensa LX6	240 MHz	external	520 KB	—	WiFi and Bluetooth on-chip. Not an ARM part, so toolchains differ.
ESP32-C3	Espressif	RV32IMC	160 MHz	external	400 KB	—	Espressif's RISC-V line — WiFi and BLE with a standard ISA.
FE310-G002	SiFive	RV32IMAC	320 MHz	external	16 KB	yes	The HiFive1 chip. Fast core, very little RAM.
LM3S6965	TI (Stellaris)	Cortex-M3	50 MHz	256 KB	64 KB	yes	Long obsolete in silicon, but a very well-supported emulation target.
nRF52840	Nordic	Cortex-M4F	64 MHz	1 MB	256 KB	yes	Bluetooth LE and 802.15.4 on-chip. The default for BLE work.
RP2040	Raspberry Pi	Dual Cortex-M0+	133 MHz	external	264 KB	—	Programmable I/O blocks let it bit-bang protocols no other MCU can.
SAMD21G18	Microchip	Cortex-M0+	48 MHz	256 KB	32 KB	—	Arduino Zero. Native USB without a second chip.
STM32F103C8	ST	Cortex-M3	72 MHz	64 KB	20 KB	—	The 'Blue Pill'. Cheap, widely cloned, extensively documented.
STM32F407	ST	Cortex-M4F	168 MHz	1 MB	192 KB	yes	Hardware FPU, plenty of RAM. A common step up from the F103.
STM32G431	ST	Cortex-M4F	170 MHz	128 KB	32 KB	—	Fast ADCs and comparators — aimed at motor and power control.

Check it against real silicon

Chiprun runs your firmware on an emulated microcontroller and hands back the UART output, so you can confirm these numbers rather than trusting them.

Chiprun docs

Frequently asked questions

Should I use an AVR or an ARM Cortex-M?

Cortex-M for almost any new design — you get more performance, more memory and better tooling for the same money or less. AVR still makes sense when you are locked into the Arduino Uno ecosystem, need 5 V logic natively, or want the simplest possible part.

What does 'external flash' mean in the table?

That the chip has no internal program memory and boots from a separate SPI flash chip. RP2040 and the Espressif parts work this way. It means an extra component on your board, a slightly slower boot, and usually more total storage for the money.

Is a faster clock always better?

No. Clock speed sets peak throughput, but most embedded work is bounded by peripherals, interrupt latency or power budget rather than raw MIPS. A 64 MHz nRF52840 with a good radio beats a 240 MHz part with none for a BLE sensor.

Which of these can I run firmware on without hardware?

The ones marked in the Chiprun column. Chiprun runs a compiled ELF on an emulated instance of the chip and returns the UART output, so an AI coding agent can test firmware without a board on the desk.

Related tools

Connector Pinout Reference

Pinouts for USB-A/B/C, HDMI, RJ45, DB9, JTAG/SWD, Raspberry Pi GPIO, Arduino and ESP32 — diagrammed and searchable.

Reference

Logic Level Reference

Input and output thresholds for TTL, CMOS, LVCMOS and LVDS, and which families you can safely interconnect.

Reference

Clock Tree & PLL Configurator

Solve PLL M/N/P/Q dividers for a target system clock from your crystal, respecting each stage's legal range.

Firmware

Timer & Prescaler Calculator

Every valid prescaler and reload pair for a target frequency on AVR, STM32, PIC and RP2040 — ranked by error, with C you can paste.

Firmware

555 Timer Calculator

Design astable, monostable and 50%-duty 555 circuits. Get the schematic, the waveform, and a bill of materials in stock E24 values.

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Battery Life Calculator

Runtime from capacity and load — including a duty-cycled sleep profile for battery-powered IoT nodes that spend most of their life asleep.

Power & Wiring