Sub-Nanosecond Resolution, Sub-Microsecond Accurate, FPGA System Timer Component

Atomic Rules TimeServo is a RTL IP core that serves the function of an FPGA’s System Timer or Clock. Although specifically designed to support the needs of line-rate independent packet timestamping, TimeServo is used where there is the need for a high-resolution, modest-accuracy timebase. TimeServo’s PI-DPLL allows a local TCXO to be disciplined by an external 1 PPS signal to achieve excellent syntonicity.


In conjunction with a timestamp-capable MAC (not included), TimeServo can be ordered as TimeServoPTP: a complete IEEE-1588v2/PTP ordinary slave device. TimeServoPTP does not require any host processor interaction to function.

Key Features

  • Single-component solution for providing coherent time within an FPGA
  • Operates with or without an externally provided Pulse-Per-Second (PPS) Reference
  • Flexible and independent clocks for control-plane and reference clock
  • Up to 32 outputs, each in their own clock domain
  • Outputs individually runtime switchable between three 80-bit formats
    • Binary 48.32
    • IEEE Ordinary
    • IEEE Transparent
  • Software control and observability from AXI control plane
  • Internal logical 120-bit resolution phase accumulator
  • Proportional/Integral controlled Digital Phase Locked Loop (PI-DPLL)
  • Observable output of digital Phase-Frequency Detector (PFD Monitor)


  • Standard AXI4-Lite Control Plane Interface
  • Up to 32 80-bit time outputs, runtime switchable binary and IEEE ordinary/transparent
  • Internal logical 120-bit Reference Clock Phase Accumulator
  • Proportional/Integral controlled Digital Phase Locked Loop (PI-DPLL)
  • Nominal Settling time: 150 s (may be changed under software control)
  • Best-Case Simulated Jitter Observation +/- 2.5 ns (with 400 MHz Reference Clock)
  • Nominal Real-World Jitter Observation +/- 10 ns (with 400 MHz Reference Clock)

Provided Examples

  • Software control utility to set/get common settings as well as observe behavior.
  • Standalone jtag/usb observation of IEEE-1588v2/PTP Ordinary Slave capability without any need for host PCIe link. (With TimeServoPTP only.)