Frequently Asked Questions about DI/OT
DI/OT general questions
Q: Is there an article that I can read to get a complete overview of the project?
A: Yep, there is this first paper that was presented at ICALEPCS2019 in New York, NY, USA:
- Low-cost modular platform for custom electronics in radiation-exposed and radiation-free areas at CERN
There are also other papers and presentations.
DI/OT hardware kit
Q: I'd like to concentrate on developing my specific hardware. What about parts that I can re-use?
A: Indeed, that is one of the reasons for the DI/OT project. Therefore wwe plan to have a complete, open-hardware kit consisting of:
- crate with CPCI-S.0 backplane
- crate controller (aka DI/OT System Board)
- power supply - here we plan to use off-the-shelf CompactPCI-Serial Power Supply Units
Q: Can I use DI/OT Backplane RTM connectors to interface with a custom backpanel?
Yes, the RTM connectors in the back of DI/OT Backplane (10114760-101LF) can mate with vertical 10052842-101LF connector. Source: Related Parts section in https://www.amphenol-cs.com/airmax-10114760101lf.html
DI/OT chassis implementation
Q: What is the DI/OT standard based on?
A: The DIOT standard is based on the Compact PCI standard. CPCI-S.0 uses Eurocard standard for boards hosted in the chassis. Then the Eurocard standard says the boards can be 100mm or larger with a step of 60mm (100mm, 160mm, 220mm,...). Off the shelf CPCI-S.0 crates use 160mm board length. However, for the DI/OT project we were asked by the users to provide more space for front boards, so we use 220mm Eurocards.
We have selected CPCI-S.0 because its backplane is fully passive and provides many I/O lines from the central System Slot to all Peripheral Slots. Therefore, we can use it for simple communication between the modules (like SPI), but we also defined two high-speed differential lanes per-slot for high speed (e.g. using FPGA MGTs) communication between the boards.
Q: How are slots in the DI/OT chassis numbered?
System Board (left most) is slot 0. Peripheral Slots are numbered left to right 1 to 8. Power Supplies are numbered left to right 1 to 2.
Q: How does it look in practice?
A: We have a work-in-progress 3D model of the crate we're designing. (Jan.2020)
Q: Having a backplane with connectors is expensive for low-cost DIY projects, isn't it?
A: We have received feedback from users of the similar system called Sinara that just use ribbon cables to connect boards together. Although that is a very low cost solution, it poses maintainability issues in the long term (e.g., when replacing boards in the crate). In fact we are actively collaborating with the developers of Sinara who plan to use the DI/OT system as an alternative for some Sinara applications.
The DI/OT system is actually not designed or optimised for low-cost DIY or hobby projects.
10 January 2020