1 Reply Latest reply on Jun 3, 2015 11:34 AM by SeyhanA_31

    hardware timestamping

      I have integrated the WICED SDK into our product, featuring the BCM43362A2.  I was asked this question on our forums, which goes way beyond my knowledge:

       

      IEEE 1588 can be implemented solely in software to give accuracy in the sub-100 microsecond range. This is similar to that seen with other software implemented protocols such as Network Time Protocol (NTP - RFC 1305) and Simple Network Time Protocol (SNTP) methods that operate across the same network topology.

      However, if timestamping is performed in the application layer, interrupts and other unpredictable software processes can introduce jitter and latency which may impair the synchronization. Even the use of a very precise external oscillator won't overcome the stack jitter associated with a software-only 1588 implementation.

      Most applications require the higher accuracy achieved by timestamping packets at the interface between the physical (PHY) and data link (MAC) layers (often referred to as "hardware timestamping"). IEEE 1588 hardware timestamping typically improves accuracy to 100 nanoseconds or better for certain network configurations, which is better than NTP, SNTP, Time-Triggered Protocol (TTP - www.ttpforum.org) and SERCOS (IEC 61491) methods.

      http://www.ieee802.org/1/files/public/docs2008/avb-rhee-802-11n-timestamp-0908.pdf
      http://www.ieee802.org/1/files/public/docs2013/tsn-phk-1AS-srv-802-11ak-links-0813-v1.pdf

      Will hardware timestamping support be provided in wifi drivers?

       

      The 2nd link mentions timestamping in association with TSF, which is also mentioned in the 43362A2 datasheet, but that's about the only information I have.

       

      Thanks, and best regards,

      mat.