This paper describes the implementation of a system for measuring entropy. The design was optimized to be implemented in a simple and small microcontroller, achieving acceptable accuracy. The system allows measuring the entropy of internally code-generated signals, and also, sampled external analog signals. The development board used M1AFS-embedded kit of Actel. In the FPGA (Field Programmable Gate Array) a microcontroller 8051 was instantiated and programmed in C language. The hardware and software design are described and also the obtained results.