The 1000-traces-puzzle

Discussion in 'Pyra News' started by EvilDragon, Jul 7, 2015.

  1. _wb_

    _wb_ Microbe Staff Member

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    What is the difference between a host port and a console port? How do you use a console port? Can you connect it to some other computer and somehow get a Pyra tty? (if so, what would be the command to "telnet" into the Pyra like that?)
     
  2. hns

    hns Very Active Member

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    The console port provides an FT232 USB to serial converter connected to /dev/ttyO2 of the Linux running on the Pyra. This allows to watch boot messages from MLO, U-Boot and the Kernel. So the external device must be an USB host and this port is just an USB slave. But you might need some FTDI driver to access the FT232 as a serial port (/dev/tty$something) on your host.To "telnet" into the Pyra you just have to answer the login: and passwd: prompts presented by getty.

    The reason to choose this solution is that we wanted to have a separate charger input (to allow the USB3 port to be switched to host mode). Therefore we already had a need for a standard socket (micro-USB).This allows to connect the Pyra to some off-the-shelf charger or notebook.

    Adding the FT232 chip and connecting it to the UART port of the OMAP was quite obvious to do. Basically it replaces an external RS232 converter for the expansion port of the OpenPandora.
     
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  3. _wb_

    _wb_ Microbe Staff Member

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    Thanks for the details. Does this mean that this charging/debug µUSB port is not a USB port from the OMAP5 point of view, but connected to its "Multichannel Buffered Serial Port" (http://www.ti.com/product/omap5432) ?

    What kind of transfer rate could theoretically be achieved through this port?

    Also, a completely unrelated question: what is the current status regarding software support for the 2D graphics core, Vivante GC320?
     
  4. Grench

    Grench Forum Addict!

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    Array speed isn't really the bottleneck on a NAS box though. RAID5 is essentially for data protection so that the array can survive single drive failures.

    In this scenario the Pyra NAS throughput capability limit is actually the networking. That either happens through a USB 2 or USB 3 dongle or WiFi. Either of those are going to max out far, far less than the 300 MB/s that the single port SATA array. Even if the SATA array topped out at 100 MB/s it would still be faster than the network connection.

    The fastest commercial NAS boxes on the market have very fancy network connections in them capable of maxing out the gigabit wired port. Even under ideal conditions with a fancy router/switch or direct connection to clients they top out between 70 and 80 MB/s.

    Although the Pyra as NAS scenario might be entertaining to build as a hobby project, the end result is likely to be more expensive than simply building a home server with one or two old AMD 2419ee CPUs, an old hot swap SATA/SAS server case, a hardware SATA RAID controller and a few 2TB or so drives.

    Just because it can be done - doesn't mean that it should be done. Cool concept though.
     
  5. _wb_

    _wb_ Microbe Staff Member

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    I'm not talking about using a Pyra as a NAS, that would be quite expensive indeed. I'm talking about a Pyra-CPU-board based NAS.

    OMAP5 could do Ethernet via USB. Since USB 3.0 can do 5Gbit/s (625MB/s), it should easily be able to max out Gigabit Ethernet, and theoretically I guess it could be connected to 10 Gigabit Ethernet.

    So the 300MB/s SATA connection could still be the bottleneck if everything else is sufficiently fast.

    Anyway, sure, you can get a cheap home server based on any desktop PC. But I'm interested in something low-power (after all it's going to be running 24/7), without any moving parts that produce noise. Desktop PCs tend to be relatively power-hungry, with CPU fans and spinning disks that produce noise.

    How much would a Pyra without screen, without keyboard etc cost? If ED could sell a full Pyra for, say, 600 EUR, then I would estimate that he could sell a significantly simplified Pyra-like home server for less than half of that price. Perhaps the simplification could even be done by taking the Pyra main PCB and not populating the non-used parts (wifi/3G/rumble/battery gauge chip/backlight leds/whatever), adding a small extra PCB for Ethernet and SATA, and designing a case around it (it does not have to be as tight and strong as the Pyra, so designing such a case should be easier).
     
  6. Eight Bit

    Eight Bit Advanced Member

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    I would consider getting something like that, if only as htpc media player/game console/nas. Some extra usb ports or an integrated hub would be nice though.
     
  7. hns

    hns Very Active Member

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    It is connected to an UART port of the OMAP5. That one can up to 3 MBit/s but one has to check the speed options of the FT232. During boot, it runs at 115200 bit/s.
     
  8. Grench

    Grench Forum Addict!

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    Must... refrain... from building microUSB to RS232 adapter to run old school modem that is physically larger than the Pyra ON a Pyra...

    Seriously - that serial port could be very handy if someone wanted to run laboratory automation equipment or holiday light shows off of the Pyra. Having it shaped like a microUSB simply makes it compact enough to exist - which is good.
     
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  9. Binky

    Binky Death's Steed Staff Member

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    How symetric is the connection logically?

    Presumably the pyra thinks its on the slave end of the serial (as well as of the USB) conection, if there is one.

    Anyway, why aren't your christmas lights Cloud Enabled? :p
     
  10. rygD

    rygD Nihilistic Mystic

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    You are not alone.
     
  11. Zink

    Zink Member

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    http://www.eurocircuits.com/can make 10-layer within 3 days, or so they say in their price calculator.
     
  12. rygD

    rygD Nihilistic Mystic

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    If it isn't too much trouble, can we get those pictures while we wait for the poll to finish up?
     
  13. levi

    levi Still fresh, damnit!

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    ED's already found a supplier who can make 10 layer boards with a rapid turnaround, which is why he's hopefully able to demo something at the next expo in August.
     
  14. Zink

    Zink Member

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    Yes, I saw the other topic only after posting that :) .
     
  15. EvilDragon

    EvilDragon Administrator Staff Member

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    And 10 layer is not 10 layer.


    The company we use doubled the production time and even had to send it outwards, because the PCB was too complex for them (MicroVias, etc.)


    My guess is that they can produce simple 10 layer boards within the 3 days and use it just for advertising :)
     
  16. fusion_power

    fusion_power Advanced Member

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    Sounds indeed more like markeing brabble then, right? :D Well why are actualy so many traces onto this little board? Is it normal to connect an OMAP5 soc to the environment or do other parts need so many wires on the CPU board?
     
  17. TrashyMG

    TrashyMG Sarcasm Dispenser Staff Member

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    The CPU module is essentially a complete computing device everything except peripherals like the keyboard, audio amplifier and such... So the SoC itself, eMMC memory, 4 SDRAM modules, supporting circuitry the two connectors that interfaces the large main board with what appears to be 80+ connectors each... so yeah a lot of traces. 
     
    Last edited by a moderator: Jul 21, 2015
  18. Natsu

    Natsu Advanced Member

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    I'm liking the look of the (back side of) case. Lol
     
    Last edited by a moderator: Jul 23, 2015

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