In the field of real-time signal processing, like most of automatic control systems nowadays present at the industry and focused on PID (proportional-integral-derivative) controllers, it is common to find software-oriented solutions based on powerful 32-bit DSP, RISC or CISC processors. This work deals with the hardware/software co-design of a PID coprocessor, all embedded on a system-on-chip device. The performances reached by a platform composed of an 8-bit MCU and a dynamically reconfigurable FPGA allow scheduling the PID algorithm as a set of tasks executed by both devices concurrently. Moreover, thanks to the flexible hardware characteristics, some modules synthesized into the FPGA are reconfigured at run-time while the rest keeps on active. This cost-effective approach, encouraged by its parallelism, is an alternative to commercial -both general-purpose and specific-purpose-processors in whatever made-to-measure engineering application