A working simulator of your board: board model, attached peripheral models, and a setup that runs your real firmware. Use it to debug, reproduce conditions, and run regressions in CI.

Do I need to modify my firmware?

No. The production ELF runs against the simulated board. No mocks, no rewrite, no special build for HardLabs.

Which MCUs are supported?

Common Arm Cortex-M families at launch, with the I²C, SPI, UART, GPIO, timer, and interrupt paths firmware leans on most. Coverage expands every release — ask us about your MCU.

What happens when a peripheral isn't supported?

We tell you which BOM parts have models and which don't. Unsupported parts can be stubbed so the rest of the board still runs, or prioritized for a model during the pilot. Coverage is explicit — we don't pretend a missing model is accurate.

How accurate are the models?

Behavioral models for analog blocks plus cycle-aware digital models for buses and MCUs. They're tuned to expose integration and timing bugs — not to replace final electrical validation on physical hardware.

HardLabs

Board simulator

Simulate whole PCBs
with firmware-in-the-loop

Q: What do I need to send you?

Schematic/netlist, BOM, and firmware (ELF/bin or source + toolchain). Cadence, Altium, and KiCad exports work at launch. You write no models.

Upload the schematic/netlist, BOM and firmware. HardLabs builds a simulator of your board and runs the real firmware against it.

Atmos G4sensor board · rev C

Ready

Design files

NETatmos.netKiCad netlist
BOMatmos-bom.csvBill of materials
ELFatmos_fw.elfFirmware · 412 KB

Board model

Simulation logUART2

Waiting for design files…

Pressure

—hPa

Temperature

—°C

Read design
Build board model
Attach part models
Run firmware

Built by hardware and software engineers fromNVIDIABloombergAmazonStitch Fix

How it works

See it work on our demo board

Start the board, plug in USB-C, drop it, heat it and talk to its firmware. From your terminal with GDB attached, in the browser, or through your AI agent.

~/demo-board · hardlabs CLI

demo board

What bugs does this find?

Catch an I²C timing violation in software

Replay the bus trace, inspect timing margins, and fail the firmware run when SCL violates the peripheral's contract.

Atmos G4checks · atmos_fw.elf

1 failed · 3 passed

I²C1 · SCL / SDAfail

SPI1ICM-42688-P WHO_AM_I0x47
SPI2BMP280 chip id0x58
I²C1DPS368 SCL t_HIGH0.42 µs
SPI3W25N01GV JEDEC idEF AA 21

at drivers/i2c.c:118 · pc 0x0800_1A4C

I²C clock stretchSCL t_HIGH 0.42µs < 0.60µs Fast-mode.

From design-partner boards

What it found on real boards

Three boards from our pilot program, names withheld. Each team's own firmware ran unchanged on its simulated board.

Agricultural sensor node

Firmware
Plugging in a charger releases the charger's hold. The firmware restores it only on its next 2 s check, so charging can run for up to 2 s while the firmware reports it held. It explained the stop message the team saw after every plug-in on the bench.
Hardware
The resistor dividers on both audio amplifiers' mode pins select a left+right mix, not left and right. A left-channel tone plays on both speakers at half volume.
Firmware
The GNSS receiver's power enable is held low and no command raises it, so position reads come back empty on the real board.

Medical wearable

Firmware
No log output from default builds. In the Makefile line “DEBUG ?= 1 # …”, make keeps the spaces before the comment, so the debug check never matched and logging was compiled out.
Design files
The netlist and the BOM disagree on two parts: the IMU variant and the flash size (256 vs 512 Mbit).

Aerospace motor controller

Hardware
As drawn, the motor driver's data-out pin never reaches the MCU, so driver register readback can't work on this revision.
Firmware
A new microstep setting isn't written to the motor driver while the axis is holding. The driver keeps the old one.
Design files
The encoder part number in the schematic doesn't exist. The connector pinout and the firmware's 16-bit reads match the SSI variant.

Headless in CI

From schematic to CI

Regression-test firmware against the simulated board on every commit.

hardlabs/atmos-firmware #142

i2c: tighten SCL high time

boot sequencequeued
spi1 WHO_AM_Iqueued
i2c1 SCL t_HIGHqueued
spi3 chip idqueued

Design-partner program

Send us your design. We'll send you a simulator.

Send schematic, netlist, BOM and firmware. We build a working board simulator you can run, debug and put in CI.

You send

schematic / netlist
BOM
firmware image

We send back

working board simulator
peripheral models
setup that runs your firmware
CI integration (pilot scope)

Board gallery

Real hardware, before you build yours.

47,434 open source boards from GitHub, each read from its KiCad files: the processor, the parts list and the board itself. Find the one closest to your design and run your firmware on it in simulation, weeks before your PCB arrives.

Browse all 47,434 boards →