Status of the low-level RF system at KEK-STF

RF field stabilities less than 0.3%, 0.3deg are required at the STF low-level rf (LLRF) system. In order to satisfy these requirements, a digital FB system using an FPGA is adopted. A total of eight cavities will be installed in STF- phase 1 and the vector sum control of eight cavity signals will be achieved. The performance of the FB system is examined using electrical cavity simulators prior to the rf operation. Other R&D projects such as the development of a simplified interlock system with an FPGA are also summarized.