WR-ZEN: Ultra-accurate synchronization SoC based on Zynq technology
Miguel Jiménez-López, Jose Luis Gutierrez-Rivas, Javier Díaz, Emilio Lopez-Marin, Rafael Rodríguez · 2016
Nowadays, many industrial synchronization systems rely on the Precise Time Protocol (PTP or IEEE1588) that provides sub-microsecond precision time transfer. However, there are some applications such as next generation of telecommunication systems (LTE-A & 5G) or scientific infrastructures that have stricter timing requirements that must guarantee the timing service regardless of traffic load conditions. Recently, the White-Rabbit (WR) technology has been proposed as alternative to provide deterministic sub-nanosecond synchronization using Gigabit Ethernet standard. Currently, most WR nodes are implemented using only FPGAs and they can be plugged in a conventional computer or can be used as standalone node. Nevertheless, this approach presents some limitations because all the functionality must be implemented in the FPGA due to the lack of a hard microprocessor on the board. The White-Rabbit Zynq Embedded Node (WR-ZEN) is a platform based on the Xilinx Zynq SoC technology that solves these issues. It has a Processing System (PS) based on a dual core ARM hard processor that can run any conventional OS like Linux and simultaneously use the Programmable Logic (PL) inside the same chip. The flexibility of the platform has motivated that WR-ZEN is under study to be used in important scientific infrastructures such as Square Kilometer Array (SKA) and Cherenkov Telescope Array (CTA) among others. In this contribution, we address the new platform design including hardware, gateware and firmware architecture. We describe the new clocking scheme, aspects of the Linux customization, kernel modules, user-space tools and the Fine Delay FMC support, clearly stating the benefits of the presented approach compared with previous WR platforms. Finally, we present experimental results and validation of the timing features compared with other solutions and we demonstrate that the WR-ZEN is fully compatible with other WR devices and it archieves a subnanosecond precision.