PICSimLab FAQ

Short, honest answers to the questions people ask most about PICSimLab – what it is, what it costs, which boards it simulates, where its ESP32 and online versions stop, and how downloads on this unofficial site work. Every answer follows the official project documentation; where the documentation says nothing, the answer says so.

What is PICSimLab?

PICSimLab (Programmable IC Simulator Laboratory) is a realtime emulator of microcontroller development boards, created by Luis Claudio Gamboa Lopes. It simulates complete boards rather than bare chips, with virtual spare parts you can wire to the pins, and it integrates with MPLAB X and GDB debuggers. New to it? Start with our getting started guide.

Is PICSimLab free?

Yes. PICSimLab is free and open source under the GPL-2.0 license (version 2, or at your option any later version). There is no subscription and no paid tier: the desktop version and the official online version are both free. Get the current stable release, v0.9.3, from our download page – every button there links to the official GitHub release files.

Which boards does PICSimLab support?

PICSimLab supports 21 boards across five simulator backends (picsim, simavr, uCsim, gpsim, and QEMU for STM32 and ESP32). They include PIC trainer boards such as McLab2 and PICGenios, the Arduino Uno and Nano, the Blue Pill (the STM32 support is only two STM32F103 boards), and the ESP32-DevKitC and ESP32-C3-DevKitC-02. One of the 21 entries, Remote TCP, is a virtual board rather than physical hardware.

Can PICSimLab simulate ESP32 WiFi and Bluetooth?

Only in part, and the official documentation is cautious about it. For the ESP32-C3, the official changelog records support for WiFi and the ESP-NOW protocol; for the original ESP32 it records incremental additions such as HTTPS over WiFi. That is patch-by-patch QEMU support, not a promise of full WiFi simulation, and there is no documented Bluetooth or BLE simulation support. Our ESP32 board page explains the real limits, and the ESP32 flash mode guide covers the DIO/DOUT-only flashing rule.

Does PICSimLab run on macOS?

Yes. Version 0.9.3, released on 20 September 2026, is the first release with native macOS builds: a .dmg for Intel Macs (x86_64) and a .dmg for Apple Silicon (arm64). Download the build that matches your Mac from our macOS download page, and if the app will not open on first launch, follow the macOS first-open fixes.

What are the limits of the PICSimLab online version?

The online version is the same source code compiled with Emscripten, and it is genuinely official – but it has no Tools menu, no debugging, and no serial communication except the IO Vterm terminal. The fastest multithreaded build runs at about 50% of desktop speed and is only tested in desktop Chrome and Firefox, and the project itself advises the desktop version for anything beyond a quick test, especially above 8 MHz clocks. You can try all three builds from our online version page.

How do I load a .hex file into PICSimLab?

PICSimLab does not edit source code, so you compile first with the tools used for real boards – MPLAB X with XC8 for PIC boards, or VSCode with PlatformIO for AVR, STM32 and ESP32 boards – and then load the resulting .hex or .bin file. Select the board and microcontroller that match your build before loading, and reload the file after every recompile. Our guide to loading a .hex file walks through it, and the hex file not loading checklist covers the common failures.

How does the MPLAB X plugin for PICSimLab work?

Install the plugin file com-picsim-picsimlab.nbm (27,091 bytes in v0.9.3) inside MPLAB X. The plugin connects MPLAB X to PICSimLab through a TCP socket on port 1234, so allow that connection through your firewall; MPLAB X can then debug and program the simulator for PIC and AVR projects much as it would real hardware. See the MPLAB X plugin guide for the setup steps, and the plugin connection fixes if it will not connect.

Is this website the official PICSimLab site?

No. PICSimLab Hub (picsimlab.com) is an independent, unofficial community resource site operated independently by its owner (contact: [email protected]). It is not affiliated with, endorsed by, or sponsored by Luis Claudio Gamboa Lopes, the PICSimLab project, Microchip, Arduino, Espressif, or STMicroelectronics. Official PICSimLab downloads are distributed only via GitHub and SourceForge (project ‘picsim’), and the download buttons on this site link to those official files. Read more on our about page.

What are the system requirements for PICSimLab?

The project does not publish any. The official documentation covers downloads for Windows, Linux and macOS, but it gives no minimum or recommended CPU, memory, disk or graphics figures, so this site does not invent any. If your computer runs one of those operating systems, pick the matching build on our download page – or try the online version first with nothing installed.