High accurate time stamping approach for time synchronization within networked instrument bus

A Yongga1, YE Lingyun2
(1. The State Key Lab of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, China;
2. College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou 310027, China）

Abstract: Networked Instrument Bus is a newly developed multimaster instrument bus protocol based on MLVDS technology. The precise time protocol(PTP) based on IEEE1588 on Networked Instrument Bus was introduced. In order to meet the higher time stamp accuracy, a new time stamping circuit for PTP was developed. The circuit detected SYNC message and Delay_Req message, and stamped the system time when these two messages were sent or received. The time stamping point was located between MAC layer and Media Independent Interface(MⅡ) to reduce asymmetry network delay. A test platform based on Xilinxs Virtex5 series FPGA chip xc5vl301ff324 was developed. The test results indicate that the time stamping circuit using phase shift clock with PLL can a gain of time stamp resolution of 1 ns and time synchronization accuracy of 10 ns.
Key words: networked instrument bus; IEEE1588; time stamp circuit; phase shift clock