Da Xue

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About Da Xue

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  1. Neil finished u-boot UMS support for us. So, soon you will be able to flash the eMMC by exposing it as a mass storage device to your PC.
  2. The two holes are for eMMC module securement. You can use double sided stickie stuff since the heat dissipation isn't that bad at 1.2GHz.
  3. Did you turn off HDMI via the GPIO? If that's on, you get about 50-100mA more because of the video pipeline. Check the schematic on the product page of the website.
  4. 0.125A is as measured with a programmable DC power supply. This number would only apply in battery or direct DC application. If you are measuring from the wall, you have to account for the losses in that power supply you are using.
  5. What power supply are you using? ARe your numbers from a programmable DC power supply? Normally not having HDMI connected at boot will usually cause the pipeline to turn off. You can also see the schematics here: https://drive.google.com/file/d/0B1Rq7NcD_39QYnltdGtWWEFvS0U/view?usp=sharing
  6. Turning off HDMI will get you pretty big gains since the display output pipeline can be turned off. The lowest I've achieved using that basic tweak is to get it down to 125mA.
  7. See https://github.com/libre-computer-project/libretech-linux/commit/9b6b181a0700b329876b7998eb75283ce0b338cc The previous USB patches that were posted to the libre-computer-project 4.14 branch were not the final ones. All of the out-of-tree patches for 4.14 can be found here: https://github.com/libre-computer-project/libretech-linux/commits/linux-4.14/libretech-cc-master
  8. S905X and RK3328 both suffer from some issues with SD cards in UHS mode. When driving them at UHS speeds of more than 100MHz, the SoCs cannot drive enough current to bring the voltages up and down enough. You see degradation of the signal and some cards are more accommodating to this than others. S905X does not have reset lines for power cycling MicroSD cards which becomes an issue when you reboot and the board tries to go back to UHS mode from non-UHS. Samsung cards that I've tested will plain drop dead while Sandisk will not re-enter UHS mode. A board power cycle becomes necessary. The SoC was designed for SD cards to be pushed in and out and did not really consider using them as boot devices. eMMC is the way to go for these SoCs.
  9. I am seeking an resolution to all the MicroSD card issues. This is why I don't touch BSPs. They are terrible and utterly unusable. Sorry about all the wasted time.
  10. I can assure you that it would take more time to fake that video than it would be to do it for real. I'm not too happy with that video because the lighting all wrong. It would kind of destroy the reputation of everyone involved if we published a fake video. The campaign was launched before all the materials were ready because of scheduling deadlines with product delivery.
  11. There's no plans for full size PCI-E cards because that is like Pandora's box in terms of customer issues. If 20V works, we could potentially design a mezzanine to drive PoE devices and act as a terminator for PoE camera system for computer vision applications.
  12. The design is not final yet. The heatsink is sufficiently big to act as a buffer so the groves are not meant to serve as headspreading fins. They are there to reduce contact surface area should you put your hand on it and lift it when it is hot. Otherwise with higher power chips, you can burn your skin.
  13. Native *speed*. Thanks for the catch. 5V and 12V works. Still trying to get 20V working.
  14. That is some bad ass sh*t.
  15. Longevity is not the only concern. At higher frequencies, signal integrity drops. The higher the clock rate, the more likely of errors due to propagation delays, leaky transistors, and threshold voltages. The difference between 0% overclock and 25% overclock may mean the difference between 30 9's to 20 9's which is statistically significant for error propagation.