IEEE 1588 time synchronization board in MTCA.4 form factor

Abstract

The distributed data acquisition and control systems in large-scale scientific experiments, like e.g. ITER, require time synchronization with nanosecond precision. A protocol commonly used for that purpose is the Precise Timing Protocol (PTP), also known as IEEE 1588 standard. It uses the standard Ethernet signalling and protocols and allows obtaining timing accuracy of order of tens of nanoseconds. The MTCA.4 is gradually becoming the platform of choice for building such systems. Currently there is no commercially available implementation of PTP receiver on that platform. In the paper, we present the module in the MTCA.4 form factor supporting this standard. The module may be used as a timing receiver providing reference clocks in the MTCA.4 chassis, generating the Pulse Per Second (PPS) signal and allowing generation of triggers and timestamping of events on 8 configurable backplane lines and two front panel connectors. The module is based on the Xilinx Spartan 6 FPGA and thermally stabilized Voltage Controlled Oscillator controlled by the digital-to-analog converter. The board supports standalone operation, without the support from the host operating system, as the entire control algorithm is run on the Microblaze CPU implemented in FPGA. The software support for the card includes the low-level API in the form of the Linux driver and user-mode library and high-level API: ITER Nominal Device Support and EPICS IOC. The device has been tested in ITER timing distribution network (TCN) with three cascaded PTP-enabled Hirschmann switches and GPS reference clock source. An RMS synchronization accuracy measured by direct comparison of the PPS signals better than 20 ns has been obtained.