Introduction:

The Optoboard System is the data aggregation and signal conversion stage of the ATLAS ITk Pixel data transmission chain. The basic working principle is:

• DATA: 6x 1.28 Gbps electrical links from the front-end modules are serialized into 1x 10.24 Gbps optical link and transmitted to the backend (FELIX).
• CMD: 1x 2.56 Gbps optical link with trigger and command are deserialized into 8x 160 Mbps electrical links and transmitted to the front-end (ITkPix). Also the Optoboard gets controlled through the optical link.

One Optoboard consists of:

• 4 lpGBTv1: one as a master available through IC, three as slaves controlled through I2C controller of the master. Manual/description here.
• 4 GBCR2: all controlled through lpGBT master I2C controller. Manual here.
• 1 VTRx+: controlled through lpGBT master I2C controller. Description here.
• 1 bPOL2V5 carrier board: houses the bPOL2V5 ASIC that converts 2.5 V to 1.2V. Datasheets here.

Specific for SLAC's test-Optopanel will be marked in red .

Mechanics:

• Up to 8x Optoboards are housed in one Optobox. One Optobox consists also of:
  • 1 Powerboard: hosts 5 bPOL12V ASICs (conversion 9 V to 2.5 V) and 1 MOPS chip
  • 1 Connectorboard: handles power distribution form the 5 bPOL12V to the 8 Optoboards according the SP chain powering/detector layout.
• Up to 28x Optoboxes (14x normal, 14x mirrored) are housed in one Optopanel.
• Each side of the ITk has 4 Optopanels.

Currently specific for SLAC IS demonstrator:

4x Optoboard V2.1 are housed in one Optobox. This Optobox is housed in a Test-Optopanel.

Interfaces:

Please refer to our Interface Document here. All the connectors of the Optoboard System is explained there.

Adapter boards:

Schematics:

All schematics for all of Berns designed PCBs can be found here.

Optoboard system support:

We collect support requests and general questions on our Mattermost channel Bern-Optoboard (invite link). Your contacts as of Aug. 2022 are Aaron O'Neill and Daniele del Santo.

Optoboard software for FELIX:

We created a repository with scripting software to easily configure the Optoboard: https://gitlab.cern.ch/bat/optoboard_felix. A lot is documented in the readme and wiki of the repository.

The repository is located in the directory:

/home/itkpix/optoboard-system

To configure an Optoboard V2.1 with the default configurations found simply run these scripts:

In a first terminal felixcore:

cd /home/itkpix/felix-sw/flx-sw-2022-08-11    # or another felix-sw version
source setup.sh
x86_64-centos7-gcc11-opt/felixcore/felixcore -d 0 --data-interface lo --elinks 0,4,8,12     # starts felixcore, check your links!

Note that the elinks might change according your connectivity scheme. More information from Ismet here.

In a second terminal do:

source flx_opto_setup.sh     # if FELIX server restart or stuck: source flx_opto_setup_fresh.sh
cd optoboard_felix
python quick_start.py -v 1.3 -s 00000000 -G 0 -d 0

The -s specifies the serial number used (00000000 is the default one for Optoboard V2.1), -G is the link number of FELIX and -d the FELIX device. If -s  is set to 00000000 and -v 1.3, optoboard_felix sends the parameters in the config ~/optoboard_felix/configs/optoboard_lpgbtv1_gbcr2_vtrxv1_3_default.json to the lpGBTs, GBCR and VTRx+. Check the FELIX documentation or the optoboard_felix readme for more information on this.

If you do flx-info link you should see that respective link aligned. If you do flx-info podpower you should see something like this (if single Optoboard outside test-Optopanel is connected similarly):

Optical power (Receive=RX or Transmit=TX) of channel in uW:
        |     0   |     1   |     2   |     3   |     4   |     5   |     6   |     7   |     8   |     9   |    10   |    11   |
        |=========|=========|=========|=========|=========|=========|=========|=========|=========|=========|=========|=========|
 1st TX |  983.30 |  986.10 |  892.10 |  970.00 |  937.50 | 1009.70 |  916.20 |  970.30 |  920.00 |  960.80 |  924.40 |  958.50 | 
 1st RX |  946.80 |  790.20 |  870.50 |  761.80 |    0.00 |    0.00 |    0.00 |    0.00 |    0.00 |    0.00 |    0.00 |    0.00 |

After fibre fanout installation:

After the fibre fanout is installed, configuring the Optoboards will look similar to this:

python quick_start.py -v 1.3 -s 00000000 -G 0 -d 0
python quick_start.py -v 1.3 -s 00000000 -G 4 -d 0    # note that -G 1,2,3 are taken by the lpGBT slave fibres
python quick_start.py -v 1.3 -s 00000000 -G 8 -d 0
python quick_start.py -v 1.3 -s 00000000 -G 12 -d 0

Or with the separate configs that are created in ~/optoboard_felix/configs:

python quick_start.py -v 1.3 -c /configs/2400003.json
python quick_start.py -v 1.3 -c /configs/2400003.json
python quick_start.py -v 1.3 -c /configs/2400007.json
python quick_start.py -v 1.3 -c /configs/2400011.json

Note that in this case the connected FELIX fibre channel has to be set inside the configuration file as described in the readme here.

In a currently ongoing effort by Bern PhD student Daniele dal Santo, the software will be integrated into the ITk demonstrator software itk-demo-sw.

Further tools:

flpgbtconf: FELIX low level tool to communicate with (and only with) the lpGBT master directly. flpgbtconf -h will give you help on the tool, here an example:

flpgbtconf -1 -I 0x74 -G 0 -d 0 ULDATASOURCE5_DLG0DATASOURCE 0x1    # sets CMD from data to PRBS7 pattern on EPTX00 and EPTX02

-I 0x74 is the address for the lpGBT and the option -1 for the lpGBT version 1. Consult the lpGBT manual for all the various register names. There are many more options with FELIX, consult the FELIX user manual.

Test-Optopanel at SLAC:

The test-Optopanel houses one Optobox with 4 Optoboards. It has a twinax inlet (round) and a fibre outlet (rectangle). The Optobox is mounted on a cooling plate with two 8 mm pipes. The

A collection of photographs from the test-Optopanel and its sister at CERN SR1 can be found here. See also this Twiki here of the SR1 test-Optopanel which has similiar information (but some very different configurations).

Optoboards:

*after power-up and inside the test-Optopanel with 9.0 V supplied. If powered outside the test-Optopanel directly on the connector with 2.5 V expect a current ~415 mA.

Connectors:

Check the above interfaces document for more detailled description.

Banana plugs are labelled according to powered bPOL12V.

Cooling and dry air inlet/outlet: FESTO 8 mm

DCS:

Currently no MOPS is mounted on the Powerboard inside the test-Optopanel (due to availability). We will ship one as soon as we got our hands on them.