The SNS Ring LLRF Control System

The low-level RF control system for the SNS Ring differs considerably from that for the Linac. To accommodate requirements for higher data throughput and improved performance the system is based on a PCI interfaced Digital Signal Processor (DSP). In accordance with SNS standards, a VME-based PowerPC © is used, but advantage is taken of the on-board PMC slot which houses a Bittware © Hammerhead © PMC card with four AD-21162 DSPs. The EPICS system handles system configuration and data traffic while the DSP performs the low-level RF controls. Protocol and software to support both the PowerPC and the DSP have been developed. This paper presents the system design and initial testing experience.