TOD Slave

NetTimeLogic’s Time Of Day (TOD) Slave Clock is a full hardware (FPGA) only implementation of a synchronization core able to synchronize to a Time of Day source via NMEA, UBX or TSIP over UART. The whole interface handling, message parsing, algorithms and calculations are implemented in the core, no CPU is required. This allows running TOD synchronization completely independent and standalone from the user application. The core can be configured either by signals or by an AXI4Light-Slave Register interface. This core only adapts the second part of the clock, and does no drift or offset correction in the sub second range, this shall be done in a combination with the PPS Slave Clock.

All calculations and corrections are implemented completely in HW.

* (Picture source Digilent Inc.)

Block Diagram


Data Stream

NMEA message at 1M baud in relation to the PPS

The PPS initiates the sending of the NMEA data stream at the GPS receiver


  • Time of Day Slave Clock
  • Built-in UART receiver with configurable baud rate
  • NMEA message parser
  • Support for NMEA GPZDA and GPRMC messages for time extraction
  • Support for UBX messages
  • Support for TSIP messages (beta)
  • Extraction of UTC info Satellites seen/locked, Spoofing and Jamming indication for UBX and TSIP
  • Quality supervision and filtering of GPRMC messages
  • Hardware time conversion from Time of Day format (hh:mm:ss dd:mm:yyyy) into seconds since midnight 1.1.1970 (Linux, TAI, PTP)
  • Second adjustment at the local second overflow
  • Seconds correction for different time bases (TAI, UTC ...)
  • In combination with a PPS Slave Clock from NetTimeLogic: synchronization accuracy: +/- 25ns
  • AXI4 Light register set or static configuration

Licensing & Pricing

 There are different licensing possibilities (more info here). All prices are in US Dollars without VAT, all prices are one-time fees, no royalties apply:

  • Project Source Code:  3100$
  • Site Source Code: 5600$

All prices are non-binding estimates – please use the contact form for definitive pricing and lead-time information.


Evaluation binaries available for Digilent's Arty and Terasic's SoCKit development boards or as Modelsim(R) precompiled libraries => contact us for free access

Tod_Slave_Flyer.pdf Tod_Slave_Flyer.pdf
Size : 85.071 Kb
Type : pdf
Tod_Slave_ReferenceManual.pdf Tod_Slave_ReferenceManual.pdf
Size : 1380.643 Kb
Type : pdf