Coral Adapters for PCIe

TensorFlow General Discussion
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I wanted a Coral for my PC, so figured I’d buy the mini PCIe card and get an adapter for installation. But it seems like nobody supports half-height cards. Now I’ve got this Coral board with no way to use it.

Does anyone know where I can get a PCIe adapter that supports Google’s difficult half-height design.

Also, the dual TPU design on the M.2 card is a great idea. But guess what, it’s just as infuriating trying to find E-key adapters! Who at Google thought hey, let’s build these things but also let it be really difficult to support plugging them into PC’s!?

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Hi Brym Stone,

Thanks for brought up the issue here! A few comments and suggestions to answer your questions…

  1. The Coral mPCIe module should be able to just plug into any mPCIe slot, so I think the issue isn’t the physical half-height for the card but rather the mother board supports the standard mPCIe interface. The module has been mostly used by industrial PCs and controllers, and we have not received any complaints about the compatibility or lack of support on those platforms. That being said, there might be some issues with the personal computers for home use, and that is also likely highly dependent on the vendor or brand of your PC. To resolved this specific issue for you, please contact our customer support team directly at coral-support@google.com, and our filed engineering team can help you look at the possible solutions. Please provide the brand and model number of your PC or the motherboard, and whatever the system configuration you have.

  2. The dual-EdgeTPU M.2 module was originally designed for one of the special business product that required dual PCIe buses, and unfortunately, vast majority of the system board vendors have not implemented this standard so far. So this is really not we built something to be difficult to use, but due to the slow or lack of the adoption by host board vendors to support the dual PCIe bus standard, which isn’t something we can control. It’s possible for making a dual-EdgeTPU module to work with the current single-PCIe bus host boards, by creating a M.2 module that uses an extra switch chip for the dual Edge TPUs, and we have discussed this with some host board vendors, and they are looking into to offer a product with this solution. But until that is done, most of the current host boards will not work with the dual-EdgeTPU M.2 module.

That being said, there are a few industry controller vendors who have products that supports the dual PICe buses. For example, Nexcom has a NDiS B537 box that supports the Coral module.

In any case, for you to use home PC (or laptop) with a Coral module, one easy alternative is to use the Coral USB module, as this module has the on-bard chip that enables USB3 interface speed if your PC supports USB3, which will get you similar performance to the PCIe bus.

But please feel free to contact our support using the email above if you wish to discuss further and explore more solution options in using the Coral products with your PC. Thank you for your interests in using Coral!

Bill Luan
Coral Team

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Thank you, Bill. I appreciate your taking the time to give detailed explanations to my gripes. I think what would greatly help PC users adopt TPU’s would be if the team managing the Coral website add the details you’ve given me to the site - or at least add reliable pointers/links to tried and trusted adapter vendors. I’ve had to scour high and low across the web often for websites to not even offer pricing because they’re industrial offerings (Asus IoT card for example); Asus in particular offer the option of contacting them for a quote, but the form provides no feedback or confirmation that it was submitted. So it’s quite pointless. But, also not your problem.

What I would love to do is have some kind of breakout board or USB adapter which could support multiple M.2 dual-Edge TPU modules to make a TPU cluster. Or perhaps you could make dual-Edge TPU USB module - then PC owners could simply buy a powered USB3 hub and fill it up. I know I’d do that in a heartbeat!

For now, I’ve had to make do with a StarTech PCIE x1 to full height mPCIe adapter card. And then MacGyver the TPU into place using cable twists (link to photo). It’s not pretty, but it works. For now.

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You are welcome, Brym, and thank you for the additional comments and suggestions! We work with Asus closely and I will pass your feedback to their website contact issue to them.

I will also pass your comments about the product links to our web team. We do have a partnership program and we list partner company’s products and services on our website. So far, most of the partners are companies whose products are for business use, and hopefully over time there will be more products from companies for IT hobbyists and DIYers will join our program, and we will certainly keep your suggestion in mind and consider listing them.

In terms of making a cluster for the EdgeTPU, most of the industry users who need this type of ML performance power, are using the Coral Accelerator module for that purpose, which give them the flexibility to design any number of EdgeTPU on board and use the PCIe bus. We also have one customer who developed a host board to support up to 12 Coral M.2 modules that provides 48 TOPS ML performance, to offer a cluster alike solution you mentioned.

Using USB is somewhat problematic, because the peculiar behavior on one of the pin traces on the EdgeTPU that require reliable signal, and using breakout board with an additional connector will mess up the signal to the chip pins in a USB3 configuration. In fact, due to this issue, most of the RPi CM4 users are having a hard time to get Coral Accelerator module to work with CM4, as CM4 typically requires a daughter board with an extra connector.

That being said, making a dual EdgeTPU USB module with the necessary mux chip on board to enable USB3 speed is possible, and we have been looking into this option. But given the flexibility provided by the Coral Accelerator chip to allow customers to design whatever the ML power they need on their own host boards, most of our customers are going that route for higher ML performance solutions, so offering a product from us isn’t a high priority at the moment. But I’ll pass your comments to our business team, as well as to some of our partners, as they could also make such a product for hobbyists.

Your adapter solution is very cool! Glad to know you got it to work, and kudos to your innovative solution. I’ll share it with our engineering team.

Thanks again for your interests in Coral and valuable feedbacks!

Bill

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No problem, Brym. And keep in mind that for business applications and implementation issues, if you running into problems using any of the Coral products, you can always contact our support team and exchange with someone there, and our support experts and our field engineers will try their best help you.

For your business solutions and projects, one of the partner listed on our site Upverter offers host board design tools and services, and one of the solutions they offer is to help customers making CM4 working with the Coral Accelerator module with the USB interface, if that ever becomes a solution you’d need to consider. Although, we generally recommend just using the standard PCIe interface with the SoC on host board for the best ML performance and data throughput speed.

Best of luck to your projects, personal or business. Have fun!

Bill

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Hi Brym,

I just saw your comment post to my Coral talk at Google IO video on YT asking about the contact for Alftel. I asked Altel to respond to your post and get back to you with the contact info, and unfortunately their reply post was deleted by YT team. Alftel’s engineer Alex asked me to let you know that you can contact them directly using the contact info on their website at www.alftel.com, if you are interested in talking to them about their multi-EdgeTPU product.

Good luck!

Bill

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Bill, this is a great example of an above and beyond level of customer service. Thank you!

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Thank you for helping people get the information they need. Great stuff as usual. Keep up the great work!!!