Thats exactly the point for this project. Also, I am hoping once we release the FPGA HDL files, the community will start adding more features like IRIG-B output, etc...
That is not true. First of all, the reason why we used the Alinx module (which you can buy of ebay as well as Amazon), was to make it easier for the community to manufacture and build. Our internal version of the time card does not include the module!
The second piece about the XC7A100T, you do not need any license to do any development as the free version of vivado is more than enough to work with.
Give us a bit of time and we will have a fully functional open HDL ready for you to add things.
It is very easy to sit down and nag about a project. I want you to understand that I had only one goal in mind when I released this project to public and that was allowing others to have a head start to work on time related project. Of course, I work for Facebook and I try to help my company with new technologies as a researcher, but helping the community and releasing the source code (to whatever I had) is just a core value of how I love to support the community.
Just give us a bit of time. We had to use some IPs that due to licensing limitations prohibited us to release the source and we were only allowed to release the bin files. We are replacing them to open source cores and we will have that part of the project available to you too. I hope you understand the situation of the project. I would love to see people adding more features to the FPGA part of it such as IRIG-B output and many other cool things that can be done. Please stay tuned.
You are right. This sentence was not supposed to be a literal description of what is the best way to build the card. It was more referring to the fact the building this card is not that hard since the main goal for this project was to liberate the time appliances from being a closed source box.
I have been working on a version with two GNSS receivers L1/L2 and L1/L5. The SA53 receives two PPS inputs and that allows you to detect Spoofing and Jamming.
Again, I like to emphasize, this is not a done work. We shared whatever we had and we would love to have the community to contribute and help making it better. I love to have as many applications as possible for this Time Card.
For example, I am looking for someone willing to port/write a Windows driver for the time card.
With regards to the VHDL code; we are working with NetTimeLogic on a version without the need of any of theirs proprietary IPs. Meanwhile, we provided you with whatever we have and we look forward to working with you.
Please feel free reach out to me if you like to collaborate on this project.
Of course we are not going to build the card in the lab with assembling SMD parts. This was more a way to explain that building such a card should not be out of access for anyone
Most (if not all) our switches in the datacenter are capable to perform as transparent clocks. With transparent clocks you can keep the time sync error down to less than 5ns per hop
Again, invented might be too strong. This is an abstraction of what you need minimally to build a time server on an open source basis. We appreciate and are humble to other products in the market
Please excuse the language “invented”. We simply meant “came up with a form factor” of having the MAC+GNSS present via PCIe bus as a POSIX clock similar to a NIC with hardware timestamping. We are humble to all the awesome products that are out there and we just wanted to present an open source version of a simplified approach to allow others to build on it.
I am very thankful to all of you putting all these questions and answers. We have a bi-weekly meeting under the open compute project and you can find previous talks there too. www.ocptap.com
That’s a good question.
GNSS gives you a 1 pulse per second signal. It is often with 20ns of accuracy. Now you need to interpolate nanoseconds between consecutive 1pps pulses. This is where a high stability oscillator is needed. You can certainly use an OCXO for the fraction of the cost of a MAC. We went for the MAC because of the importance of the role that the device plays in our datacenter