DTC

Repository for the Outer Tracker DTC for the CMS experiment at CERN

Contents

• DTC
  • Contents
    • Local build instructions
      • Pre-requisites
        • Setup steps
        • Clone common packages
        • Clone DTC specific packages!
        • Create an example project
      • Build and package firmware
    • Input
    • Front End Processing
      • Pre-conversion format
      • Post-conversion format
    • Back End Routing
      • Formats
        • Constants
        • t_stubFE

Local build instructions

The best way to build and validate the firmware is via the CI! But for development and debugging it might be sometimes more convenient to build locally. In order to do this, check out the pre-requisite packages below and then follow the instructions to build the project with ipbb, or use the Vivado GUI.

Pre-requisites

Note: You need to be a member of the cms-tracker-phase2-backend-development egroup in order to clone the emp-fwk repository. In order to add yourself to that egroup, go to the "Members" tab of this page, and click on the "Add me" button; you may need to wait ~ 24 hours to get access to the GitLab repo

Note: You need to be a member of the cms-tcds2-users egroup in order to clone the cms-tcds2-firmware repository. In order to add yourself to that egroup, go to the "Members" tab of this page, and click on the "Add me" button; you may need to wait ~ 24 hours to get access to the GitLab repo

Setup steps

Download and source ipbb the IPbus Builder Tool, and initialise the environment.

curl -L https://github.com/ipbus/ipbb/archive/dev/2021j.tar.gz | tar xvz
source ipbb-dev-2021j/env.sh

kinit your_user_name@CERN.CH

ipbb init working_dir
cd working_dir

Clone common packages

Clone all packages necessary for the DTC project to build.

ipbb add git https://:@gitlab.cern.ch:8443/p2-xware/firmware/emp-fwk.git -b feature/daqpath_v2
ipbb add git https://gitlab.cern.ch/ttc/legacy_ttc.git -b v2.1
ipbb add git https://:@gitlab.cern.ch:8443/cms-tcds/cms-tcds2-firmware.git -b v0_1_1
ipbb add git https://gitlab.cern.ch/HPTD/tclink.git -r fda0bcf
ipbb add git https://github.com/ipbus/ipbus-firmware -b v1.9
ipbb add git https://gitlab.cern.ch/gbt-fpga/gbt-fpga.git -b gbt_fpga_6_1_0
ipbb add git https://gitlab.cern.ch/gbt-fpga/lpgbt-fpga.git -b v.2.1
ipbb add git https://:@gitlab.cern.ch:8443/gbtsc-fpga-support/gbt-sc.git -b gbt_sc_4_1

Clone DTC specific packages!

ipbb add git https://gitlab.cern.ch/dmonk-emp-projects/histogram.git
ipbb add git https://gitlab.cern.ch/cms-tracker-phase2-data-processing/BE_firmware/dtc.git -b feature/daqpath_tb
ipbb add git https://gitlab.cern.ch/cms-tracker-phase2-data-processing/BE_firmware/dtc-stub-processing.git

Create an example project

(DTC project with daqpath is available only with dtc-mini so far.)

First create a project area by sourcing the desired project dep file. For example, for the 2S DTC-mini project on a KU15P,

ipbb proj create vivado my_dtc_test dtc:top/dtc-mini/2S-5G ku15p_sm1_v1/top.dep
cd proj/my_dtc_test

and similarly, for the PS 5G DTC-mini project on a KU15P,

ipbb proj create vivado my_dtc_test dtc:top/dtc-mini/PS-5G ku15p_sm1_v1/top.dep
cd proj/my_dtc_test

Note: For the following commands (not always necessary), you need to ensure that can find & use the gen_ipbus_addr_decode script - e.g. for a standard uHAL installation

export PATH=/opt/cactus/bin/uhal/tools:$PATH LD_LIBRARY_PATH=/opt/cactus/lib:$LD_LIBRARY_PATH
ipbb ipbus gendecoders

Finally, generate the project

ipbb vivado generate-project --single

The generated .xpr project file can be opened with Vivado if desired.

Build and package firmware

To use ipbb to build the firmware and package the bitfile with corresponding address tables run,

ipbb vivado synth -j4 impl -j4
ipbb vivado package

Input

Data is received at the DTC from 72 lpGBT links from FE modules on the detector. The format for the packets sent over the link can be found in the spec doc.

Front End Processing

The link decoding stage of the DTC consists of both a framer within the datapath and a set of entities in the payload for each input link. The framer converts the wide xGBT word (112 bits at 40MHz) to a stream of 10-12 bit words (5-6 bits per CIC) sent over 8 clock cycles per 40MHz.

The two CIC data streams are individually processed to extract the stubs, then combined into a single stream to be sent to the Back End Processing.

Pre-conversion format

The first 18 bits represent the stub information, followed by the header for the boxcar. Type: lword

Post-conversion format

Type: lword

Back End Routing

Formats

Constants

t_stubFE

Type: record

Used as an interface format between the FormatInput and Transform.