memory access

This topic contains 9 replies, has 3 voices, and was last updated by  Gà Rừng Mạnh Mẽ 3 years, 4 months ago.

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  • #31356

    renee
    Member

    Hi, I am doing some image processing with Minimorph. As you may know, I need to use a lot of arrays to achieve this.Thus, my plan is store some matrix to the board memory and read it when running the program. What is more, I will connect a camera at the HDMI port, and read the image file whenever the camera takes a picture. My problem is, I can’t find the way to access the memory and read data from memory. I also need to know the method of listening and reading data from HDMI port (or other ports). Is there any commands to support this requirements?

    #37733

    alastair
    Moderator

    The HDMI connector on the Minimorph is driven by a Silicon Image SiI9022A HDMI transmitter, which is output-only. So it will not be possible to connect a camera to the HDMI connector and receive data from the camera.

    However, it is possible to connect a camera to the USB port and receive data from the camera. You will need to power the board via the DC in socket.

    The reading of data from a camera can be done by a Linux userland application. The programming methods for doing this are the same on a Minimorph as they would be for any other Linux-based device and will depend partly on the driver for the specific camera that you use.

    #37734

    renee
    Member

    Dear Alastair,

    Some things to be confirmed.
    Firstly, could you please offer me a way to access to the memory of the board? I want to write and read data from the memory during the progress of my application.
    Sencondly, did you mean the only port support input is the Mini USB port (except audio in) ?
    Tirdly, to my knowladge, the only way of runing an userland application is via the codescape debugger. Which means, I have to load the program to the board during the debugger and run it by clicking the run button of the debugger. Thus, the minimorph board can not run the userland without the help of host PC. Is that right?
    Thank you in advance.

    #37735

    alastair
    Moderator

    Any userland application can be added to your Linux filesystem as explained in the Reference Manual. You can also place a program on an SD card and run it from there, by starting it from Linux. If the program needs libraries contained in the main Linux filesystem then it must be copied into the main Linux filesystem then run from there.

    Why do you want to access the RAM on the board? To do so would require altering the bootloader (to change the area of RAM reserved for the OS).

    There are other ports on the Minimorph that can operate as input ports, but the most sensible one to use for input from a camera is the USB port.

    #37736

    renee
    Member

    I plan to store some data in the memory and use read it duing the progress of the application. The data is too big so it is not very suitable to write inside my code. (a very big matrix)

    After rereading the Reference Manual, I found it explianed it in very short words. The manual only tells me I can load the userland application to the filesystem or the SD card but hasn’t offer any details. Could you please tell me how to run the application after I loading it to the SD card or filesystem? How to control them or chose which one to be run when there are more than one application loaded in the card or silesystem? (In this case, I need two applcations. One for reading data from camera and transform the formate, one to do the facial recognition processing)

    #37737

    renee
    Member

    Another question is, if I connect the camera via USB port, where can I find the data send by the camera ? I mean, if I connect the camera to my host PC, I go to the filesystem and find the folder of my camera device , then I get the data. Where should I go to looking for the data in the minimorph system?

    #37738

    alastair
    Moderator

    You would use a Linux driver to control the camera from the Minimorph.

    #37739

    renee
    Member

    Hey, sorry to trouble you but I want ask a following question. If I need to load a file into the minimorph filesystem, firstly, I need to add it to the “buildroot/output/target” folder , then rebuilt the kernel and load the “metag-linux/arch/metag/boot/vmlinux.bin” file to my SD card. Finally, using U-Boot to realize it. Am I right? Is there any other way to put files into Minimorph filesystem ? It will be better to me if I don’t need a SD card.

    #37740

    alastair
    Moderator

    You would need to convert the metag-linux/arch/metag/boot/vmlinux.bin file to a vmlinux.ub file (using the U-Boot tools) before copying the vmlinux.ub file to an SD card.

    If you can use an SD card then it is simplest to copy the file onto the SD card. The card will be automatically mounted when Linux boots. You can then access the SD card from Linux running on the Minimorph.

    #37741

    thank to poster

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