Screen Shots










gpsim is a full-featured software simulator for Microchip PIC microcontrollers distributed under the GNU General Public License, Version 2 or higher, and some of it's libraries under GNU Lesser General Public License, Version 2 or higher.

gpsim has been designed to be as accurate as possible. Accuracy includes the entire PIC - from the core to the I/O pins and including ALL of the internal peripherals. Thus it's possible to create stimuli and tie them to the I/O pins and test the PIC the same PIC the same way you would in the real world.

gpsim has been designed to be as fast as possible. Real time simulation speeds of 20Mhz pics are possible. ( A 'goto $' program runs at the same speed as a 25Mhz pic when simulated on my 400Mhz PII Linux Box. Of course, as you add stimuli and begin interacting with peripherals, the performance drops. But it's still fast!)

gpsim has been designed to be as useful as possible. (At least that's the intent - honest.) The standard simulation paradigm including breakpoints, single stepping, disassembling, memory inspect & change, and so on has been implemented. In addition, gpsim supports many debugging features that are only available with in-circuit emulators. For example, a continuous trace buffer tracks every action of the simulator (whether you want it or not). Also, it's possible to set read and write break points on values (e.g. break if a specific value is read from or written to a register).

gpsim is not fancy, but it's improving. It supports a good ol' fashioned CLI like gdb and a gui based on gtk.

Screen Shots

Register viewer

Source browser

Bread board viewer.

Scope viewer 1. Scope viewer 2.



To build gpsim from the latest released source, download the source tarball .

If your distribution does not have a current or patched version of gtk+extra, then you should download gtk+extra, build it, and install it prior to building gpsim.


Borut Ra┼żem has ported gpsim to Windows and called the package "gpsimWin32". In addition, he's created a slick installer and makes regular snap shots.


The current gpsim SVN source can be browsed using the gpsim SourceForge SVN browser.

To get the gpsim SVN source tree for local build, follow the instructions for getting gpsim from SVN which provides a step-by-step description on how you can get the code.


Download the gpsim tar ball and type

tar -xvzf gpsim-0.x.y.tar.gz

Where 'x.y' is the version number. This will create a subdirectory called gpsim-0.x.y . All of gpsim's source code will be untarred to here. From there, you can read the README and INSTALL.gpsim files for more info. But they basically tell you to

cd gpsim-0.x.y
./configure This will create the Makefile
make <--- This will create the executable
su root if you have root privileges
make install places a copy of the executable in /usr/local/bin

Oh, don't forget to check the gpsim-0.x.y/examples subdirectory for some example asm and stimulus files...

Supported Processors
As processors are being added all the time, the best way to determine currently supported processors is to run the command "processor list" in the Command line of Gpsim. If you would like to use a processor not currently supported by gpsim please request it in a "Feature Request".(see support)

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* USB functionality not supported (yet).


Here's the current gpsim documentation , gpsim.pdf, or gpsim.html.

Or if you prefer, here's the Lyx source gpsim.lyx.


The gpsim-devel mailing list is devoted to gpsim specific issues. While primarily intended for gpsim development, this list may also be used as a user resource to ask any question.

In addition to the mailing list, bug reports and feature requests can be filed at the gpsim SourceForge tracker.


gpsim supports loadable modules. This means that it is is possible to add devices to gpsim that are totally separate from gpsim. They reside in their own libraries and are distributed separately. The goal, of course, is to provide the simulation infrastructure for users to easily construct a custom simulation environment.

gpsim provides a basic module library with the following components:

  • Pullup/Pulldown resistors
  • switch
  • AND, OR, XOR, and NOT Logic Gates
  • Single or 7-segment LEDs
  • PAL Video emulator
  • Rotary Encoder

The gpsim LCD module provides support for character LCD displays.

Related Links

gpasm - The GNUPIC assembler that is compatible with MPASM.

gpsim Source Forge Project page contains the SVN source for gpsim.

gpsim Native Win32 port.

Byte Craft is the creator of the .cod symbol file format.

The gnupic webpage has links to other pic tools. Paul Vollebregt has another gnupic webpage with links to tools for other microcontrollers as well.

This page is maintained by the gpsim administrators gpsim-devel
Last modified on $Date: 2017-06-12 18:27:42 +1000 (Mon, 12 Jun 2017) $.

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