gpsim is a open source simulator for Microchip's PIC microcontrollers. gpsim is a full-featured software simulator for Microchip PIC microcontrollers distributed under the GNU General Public License and GNU Lesser Public License(see the LICENSE section).

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 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.

gpsim can be controlled from either a graphical user interface (GUI), a command line interface (CLI) or by a remote process. Typical debugging features like breakpoints, single stepping, disassembling, memory inspect & change, and so on are all supported. In addition, complex debugging features like real time tracing, assertions, conditional breaks, and plugin modules to name a few are also supported.

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

The license of this software is Free, you can free download and free use this network utility software.