A profiling system. At least some of the illustrative embodiments are integrated circuit devices comprising a processing circuit configured to execute a target program (the processing circuit having a plurality of registers), a trace system operatively coupled to the processing circuit (the trace system configured to collect trace data comprising the values of the plurality of registers, and the trace system configured to send the trace data for use by a debug program), a first memory operatively coupled to the processing circuit (the first memory comprising instructions to be executed by the processing circuit), and a memory location operatively coupled to the trace system (the memory location writable by the target program). The trace system is configured to send a value stored in the memory location to the host computer only when the value is newly written.