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I'm programming the FPGA on the Red Pitaya and I'm using it for gathering datas and generating images with those datas. Then, I need to transfer the images to an Android device. I so need to use the USB port (for connecting the board to an Android device) and I was wondering what transfer protocol I should use for the image transfer. UDP over USB? Serial over USB? Other?

Or maybe something already exists on the Red Pitaya?

Thanks for your answers.

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    \$\begingroup\$ Either bulk or isochronous transfers. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Jan 7, 2016 at 9:33
  • \$\begingroup\$ If you've got local storage for the images as you generate them, maybe present as a mass storage device? \$\endgroup\$
    – pjc50
    Commented Jan 7, 2016 at 9:33
  • \$\begingroup\$ Most special-purpose USB devices seem to present themselves as serial adapters, since that's a simple and well-supported protocol. I don't know if it has support on Android, though. (Another factor for them choosing this is probably the availability of FTDI USB-to-serial interface chips) \$\endgroup\$
    – Criticizing Israel not allowed
    Commented Jan 7, 2016 at 9:39
  • \$\begingroup\$ Thanks for your answers. If I'm not wrong, it's more isochronous than bulk as I would like to do a streaming... Which answers to pjc50. For the Android device part, a usb a to usb b is enough if I'm not wrong. I saw some apps to do the job. The remaining problem still on the RP side of the communication. \$\endgroup\$
    – Mouha Legrand
    Commented Jan 7, 2016 at 10:01
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    \$\begingroup\$ Do you have the ability to write your own drivers and load them onto the android device, or do you have to pretend to be a device which is already known to the kernel? \$\endgroup\$
    – pjc50
    Commented Jan 7, 2016 at 13:37

2 Answers 2

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look for FT232h ftdi converter... even if you dont have on your board , you can interface it with spare I/Os... you may find cheap breakout boards in ebay or aliexpress...

Im not 100% sure , but i think there is some driver for android...

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There is already an FTDI RS232 converter on your board, wired to one of the micro-USB sockets. If the amount of data you want to transfer is moderate, you can use that. You could expect to get 1Mbit/s through such a converted, sometimes a bit more. I don't own such a board so this is just an estimate.

If you need to transfer lots of data and 1Mbit/s is not enough, you should be using Ethernet over USB. See if you have a kernel module called g_ether available for your kernel.

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  • \$\begingroup\$ The RS422 versions of the FTDI converters I have used can get up to just about 3Mbps. \$\endgroup\$
    – user4574
    Commented Dec 29, 2016 at 4:48
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    \$\begingroup\$ FTP is a completely unsuitable protocol for streaming data. It's aimed at transferring files, not arbitrary data, and is relatively complex to implement. HTTP might be a better fit, as it at least has some provisions for streaming data. \$\endgroup\$
    – user39382
    Commented Mar 3, 2017 at 23:03
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    \$\begingroup\$ @duskwuff The OP specifically mentions transferring images to an Android device. What's wrong with transferring these as files? \$\endgroup\$
    – Dmitry Grigoryev
    Commented Mar 6, 2017 at 10:24
  • \$\begingroup\$ @DmitryGrigoryev The question title specifically asks for a solution for "streaming over USB". FTP is not a streaming protocol. \$\endgroup\$
    – user39382
    Commented Mar 6, 2017 at 15:11
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    \$\begingroup\$ @uuser39382 Images are not a suitable kind of data for streaming to begin with. It's either still images as files or video as a stream. \$\endgroup\$
    – Dmitry Grigoryev
    Commented Jul 12, 2021 at 14:20

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