PXL timing

There are two asynchronous systems.

STAR PXL RDO

L0 triggerL0 detectors

Physics collision

Trigger processing

TCD distribution

1.5 us

TBD

RDO board clock/Start

MTB buffering

Sensor frame begin tx

MTB buffering

RDO board rx

250 ns*

Total Trigger Delay (TTD)1.75 us

* To be verified

PLAN• Use an oscilloscope to measure the transit time from the START generated

on the RDO board to the receipt of the START on the low mass cable section.• Add the time from the Ultimate manual from the receipt of START to the first

row processing.• The time offset between the send of START from the RDO motherboard

(internal time pointer) and the beginning of the first row processing is then TD + FPD

• This will be done with the production cables, MTB and feedthrough.

PXL RDO tx MTB buffering Ladder sensorSend start

Transit Delay (TD)

PXL RDO

LVDS measured on one side of termination resistor.Blue trace – Falling edge of START measured at RDO board R34Yellow trace – START (opposite polarity) measured on driver board R95

Transit Delay = 79 ns

PXL RDO tx MTB buffering

Sensor frame begin txMTB bufferingRDO board rx

Ladder sensor

PXL initial startup timing

Send start

Ladder sensor

Delay until frame starts

Delay until past frame header

RDO boardSerdes processing

First frame latency

We will measure the full latency through the system from the transmission of the START to the arrival of the first frame header at the RDO board

LVDS measured on one side of termination resistor.Blue trace – falling edge of START measured at RDO board R34Yellow trace – Sensor1 data output 1 (opposite polarity) measured on RDO board R1.

First frame latency = 7.093 us