Abstract--Hardware/Software codesign of Elliptic Curve Cryptography has been extensively studied in recent years. However, most of these designs have focused on the computational aspect of the ECC hardware, and not on the system integration into a SoC architecture. We study the impact of the communication link between CPU and coprocessor hardware for a typical ECC design, and demonstrate that the SoC may become performancelimited due to coprocessor data- and instruction-transfers. A dual