TiCkS: A Flexible White-Rabbit Based Time-Stamping Board

TL;DR

The paper presents TiCkS, a flexible, FPGA-based time-stamping board with nanosecond precision, designed for use in Cherenkov Telescope Array cameras and adaptable for various experimental setups.

Contribution

It introduces a novel, FPGA firmware-based time-stamping solution with a TDC and UDP communication, enhancing flexibility and precision in experimental trigger signal timestamping.

Findings

Achieves ns-precision time-stamping of trigger signals up to 400 kHz.

Provides a flexible, small-form-factor design suitable for CTA cameras.

Offers an open hardware FPGA mezzanine card for diverse input/output configurations.

Abstract

We have developed the TiCkS board (Time and Clock Stamping) based on the White Rabbit (WR) SPEC node (Simple PCIe FMC carrier), to provide ns-precision time-stamps (TSs) of input signals (e.g., triggers from a connected device) and transmission of these TSs to a central collection point. TiCkS was developed within the specifications of the Cherenkov Telescope Array (CTA) as one of the candidate TS nodes, with a small form-factor allowing its use in any CTA camera. The essence of this development concerns the firmware in its Spartan-6 FPGA (Field-Programmable Gate Array), with the addition of: 1) a ns-precision TDC (Time-to-Digital Convertor) for the TSs; and 2) a UDP stack (User Datagram Protocol) to send TSs and auxiliary information over the WR fibre, and to receive configuration & slow control commands over the same fibre. It also provides a PPS (Pulse Per Second) and other clock signals to the connected device, from which it can receive auxiliary event-type information over an SPI link (Serial Peripheral Interface). A version of TiCkS with an FMC connector (FPGA Mezzanine Card) will be made available in the WR OpenHardware repository, so allowing the use of a mezzanine card with varied formats of input/output connectors, providing a cheap, flexible, and reliable solution for ns-precision time-stamping of trigger signals up to 400 kHz, for use in other experiments.