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Open source USB Type-C to HDMI Adapter
- vsampath 12y agoFor what it's worth, this appears to be an active dongle using a MegaChips device to do the DisplayPort to HDMI 2.0 conversion. USB Type-C alternate mode handles the passing of DisplayPort audio/video data from the GPU over the USB pins (ML0-3), and the MegaChips device converts that to HDMI 2.0 TMDS signaling.
- lsaferite 12y agoDo you have a link to the datasheet for the DP-HDMI2 chip? I tried searching based on the part number and apparently my google-fu was weak.
- vsampath 12y agoNo, my Google-fu also failed me. There's also an SPI ROM that is an input into the DP-HDMI2 chip, so there's likely firmware there that is not part of Google's open-sourcing.
- tdicola 12y agoIs there a layout yet or is it just a schematic? From what I understand USB 3.0 is so crazy fast it requires quite a bit of RF magic/knowledge to even just route from the connector to a chip on a board.
- platinum1 12y agoYep, not to mention the manufacturing technologies required to meet the length matching and impedance targets. It's probably not realistic for hobbyist projects. I think this is mostly useful as a reference for making other types of adapters that might only need to use USB 2.0, but still need the microcontroller to negotiate the Type C stuff. edit: There are two other open source Type C projects (and they stick with the Hostess snack theme): http://www.chromium.org/chromium-os/twinkie http://www.chromium.org/chromium-os/twinkie http://www.chromium.org/chromium-os/dingdong http://www.chromium.org/chromium-os/dingdong
- nknighthb 12y agoAt what point do consumer devices start using internal optical interconnects?
- thrownaway2424 12y agoNever? Why do you think this would help anyone?
- nknighthb 12y agoEase of routing. I know optical on-chip networks have been the subject of research for many years, and I've heard rumblings of optical interconnects between chips. I don't know their current status, nor whether they look to be useful in practice. Hence my question.
- reportingsjr 12y agoIf you mean directly from an IC then there is a long way to go on that. They are still trying to figure out how to make lasers on an IC in the same CMOS process as normal ICs.
- rcfox 12y agoWhile not usually meant for carrying high-speed signals, there are optical isolators[0] that are used to communicate between circuits that are not connected electrically. I'd guess that fiber optics is only a net win over large enough distances that you make up the latency from converting electrics signals to optical and back. [0] http://en.wikipedia.org/wiki/Opto-isolator http://en.wikipedia.org/wiki/Opto-isolator
- raverbashing 12y agoThese are most for electrical insulation, not high speed (most probably aren't made for high speed) It's a whole different problem to have even a short distance connection go up to GHz speeds.
- retroencabulato 12y agoWho do you expect to be able to use this information? Yes, basic high-speed electronics experience is required.
- tdicola 12y agoAnyone who wants to actually build the board. USB 3.0 is a whole new ball game and has lots of gotchas with board layout & design. Check out Jared Boon's Daisho talk for some good background on USB 3.0 challenges: https://www.youtube.com/watch?v=eTDBFpLYcGA&t=1059 https://www.youtube.com/watch?v=eTDBFpLYcGA&t=1059
- fnordfnordfnord 12y agoWith such a small pcb and so few external components, even an amateur with a little luck might get this to work.
- cnvogel 12y agoPlease note that this adapter does NOT use USB3.0 signalling. The only USB signalling going on is USB2.0 to the STM32 micro which seems to configure the actual Display-Port to HDMI-Bridge chip. The "High Speed Lanes" (on which normally USB3.0 data is transferred) is re-purposed as a displayport connection. (in the block diagram ML(0…3)± are the differential display-port "lanes", they are connected to the USB "C" plug SSD(p/n)(1…4) shielded differential pairs)
- j_m_f 12y agoThere are both schematics as well as board layout gerber files posted on the site.
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- rcfox 12y agoWhile the firmware may be open source, the hardware is not. It's not enough to be able to see the schematic in a PDF; it's important to have proper, machine-readable, design files. Nobody would consider a print-out of the Linux kernel's source code to be an acceptable means of distributing it.
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- thrownaway2424 12y agoI think these are designed to be used with developer boards like http://www.digikey.com/product-detail/en/STM32072B-EVAL/497-14097-ND/4502080 http://www.digikey.com/product-detail/en/STM32072B-EVAL/497-...
- makomk 12y agoDoubt it, they require a special DP to HDMI converter IC, and you basically have to build a custom PCB in order to route the high-frequency DisplayPort and HDMI signals properly. May as well stick the microcontroller on the board too because that's easy to lay out compared to everything else.
- GuamPirate 12y agoI do not actually think that is incredibly important.
- retroencabulato 12y agoI disagree. Standalone gerbers aren't terribly useful for hobbyists, and you'd have no luck opening an Allegro project even if they released that (which they wouldn't due to in-house component libraries containing supply leads etc.) This remains an excellent reference design to build upon. The world of PCB design is more labor intensive, but this would be perfectly simple to reimplement using hobby-level PCB software.
- tlb 12y agoThis is interesting, because lots of cheap clones of the adapter will appear and quickly drive the market price below $5. There has been a dichotomy for several years: generic adapters are $2-$5, while proprietary adapters are $20-$50. It's not due to the BOM cost of the chip, which is probably less than the cost of the copper. This might be the first mainstream adapter with a chip, other than PL2302-based USB-serial adapters, that are cheap.
- lucaspiller 12y agoYou can already get a wide range of Chinese clones of proprietary Apple adapters for under $3: http://m.ebay.com/itm/131250380700 http://m.ebay.com/itm/131250380700 http://m.ebay.com/itm/111573913018 http://m.ebay.com/itm/111573913018 Some are actually better than Apple, the braided lightning cables are a lot harder to break. You can even get them with LEDs if that's you thing. In my experience they work just as well, but quality can sometimes really vary. I hope this leads to cheap clones from reputable manufacturers who have high quality standards.
- 13 12y agoMost Chinese lightning cables tend to get blocked by apple or just generally fail on their own.
- lucaspiller 12y agoThe cables have advanced a lot since this article: http://gizmodo.com/5954542/china-finally-cracks-apples-secret-iphone-5-cable-here-come-the-cheap-clones http://gizmodo.com/5954542/china-finally-cracks-apples-secre... I'm using a cable now that looks exactly the same as an official Apple one and works just as well (iPhone 5S iOS 8.2).
- coldpie 12y agoI had some generic DP->HDMI adapter fail out of the box while setting up our booth at GDC last week. Luckily we had a spare, and the other five adapters worked fine. I do wonder if official Apple adapters have the same failure rate; maybe we just got unlucky.
- jammyrose 12y agogreat articel, the point you made are apt.
- swamp40 12y agoSo, why do these guys design things and then just give all the files away on the internet? Or is my midwestern-ness showing?
- gima 12y agoI'm quite a newbie with electronics, but the workhorse of this device seems to be a chip named "MCDP2850", and I can't seem to find this chip anywhere. I've also encountered this kind of "failure to find chips pertaining to DisplayPort/HDMI/DVI" before. How do people find these chips - both when designing - and as hobbyist who needs the chip?