Nowadays, with the increasing densities of FPGA devices, embedded systems based on microprocessor cores are being integrated inside these devices. However, memory size and power dissipation remain a major challenge when integrating embedded system in such components. This paper presents a low-power architecture, with small memory footprint, adapted to FPGA-based integrated systems. A microcontroller is then designed using this architecture. It is a Java processor that implements a stack machine, borrowing the Java advantages, like high portability, code reuse, and others.