Proton Calorimetry/Experimental Runs/2021/Apr1

Daisy chain tests of second DDC232 prototype in D109

Aim: Debug "mirroring" issues when daisy-chaining more than 2 DDC232s boards. Test signal quality across boards using 500MHz oscilloscope.

Notes

• 3 DDC232 boards have S12915-16R photodiodes.
• 4th DDC232 board has 1k ohm resistors.
• In the runs below, boards are enumerated right to left, with the right-most board (1st board) connected to the FPGA.
  • In the configuration column, P = board with photodiodes and R = board with resistors. The first board listed in this column is connected to the FPGA.
• In all runs, an integration time of 170us and full-scale range of 350pC is used.

Traces saved in /unix/www/html/pbt/wikiData/images/DDC232/20210401

Run	Board Configuration	Scope Trace Description	Video
1	P	Yellow trace shows DVALID at FPGA, blue shows DVALID at J2 of DDC232 board.
2	3, 4	Rotation of boards followed by swept covering of a few photodiodes in turn with black cloth. Boards initially facing downwards but rotated upwards to expose to room lighting. Sweep begins around 10s mark. Note similar behaviour to above.
3	3, 2	Rotation of boards followed by swept covering of a few photodiodes in turn with black cloth. Boards initially facing downwards but rotated upwards to expose to room lighting. Sweep begins around 5s mark. Note that channels 1-16 show no output as they have been replaced with resistors; also, there is no mirroring.
4	3, 1, 4	Rotation of boards followed by swept covering of a few photodiodes in turn with black cloth. Boards initially facing downwards but rotated upwards to expose to room lighting: boards rotated repeatedly to examine signal dropouts on board 4. Sweep begins around 47s mark. Note that the mirroring is the lowest of the photodiode pairs on boards 1 and 4. Note also that very noisy signals and signal dropouts are seen on board 4 (photodiodes 1-16) and that this is not replicated on board 1; so whatever is causing this noisy behaviour does not contribute to the mirroring. Compare this to run 2 above where these noisy signals and dropouts are not seen.
5	3, 4, 1	Rotation of boards followed by swept covering of a few photodiodes in turn with black cloth. Reording of boards from run 4 above. Boards initially facing downwards but rotated upwards to expose to room lighting. Sweep begins around 25s mark. Note that the behaviour is similar to run 4 with board 4 still noisy and that this noise is not mirrored but that the low signals are mirrored between boards 1 and 4.
6	3, 4, 1	Swept uncovering of each photodiode in turn. Sweep begins near the start of the video but it only seen in the signals once board 1 is fully uncovered and board 4 starts to be uncovered. Mirroring appears to be connected to lowest output, not largest, for mirrored pairs.
7	3, 4, 1	Swept uncovering of each photodiode in turn - in opposite direction to run 6 - followed by board rotation and swept covering with finger. Note that board 4 shows zero output during uncovering due to signal dropouts associated with rotation. Low signals around 1m25s mark are a results of covering photodiodes partially with a finger.
8	4, 3, 1	Swept uncovering of each photodiode in turn followed by board rotation and swept covering with finger. Repeat of run 7 above but with board reordering. Note that board 4 no longer shows noise when rotated now that its the last board in the chain.
9	3, 4, 2	Rotation of boards followed by swept covering of a few photodiodes in turn with black cloth. Now includes board 2 with resistor-shorted photodiode connections. Note that neither boards 4 or 2 show any output, corroborating that low values are mirrored despite board 4 being exposed to light.
10	3, 2, 4	Rotation of boards followed by swept covering of a few photodiodes in turn with black cloth. Reording of boards from run 9 above: note that the behaviour is similar with no output from boards 2 and 4.
11	3, 1, 4, 2	board rotation and sweep covering of photodiodes
12	3, 4, 2, 1	board rotation and sweep covering of photodiodes
13	3, 2, 1, 4	board rotation and sweep covering of photodiodes