Cooja is an open source network simulator.
MSPSim is a Java-based instruction level emulator of the MSP430 series microprocessor and emulation of some sensor networking platforms. It is used by Cooja to emulate MSP430 based platforms and is included as a git sumbodule.
To initiate and update the MSPSim submodule:
$ git submodule update --init --recursive
The MSPSim source code is available at Github: https://github.com/contiki-ng/mspsim