PC to DE2-115 USB Communication

Question

Hi,

I'm looking for information on transferring data from a PC to DE2-115 through USB for a class project that I'm working on. Specifically, I have a grayscale image that I want to transfer to the FPGA, run some processing algorithms on the FPGA and output the processed image through the onboard VGA. I've tried working through the USB_DEVICE demonstration but there is no accompanying documentation that explains what the code does and how it is structured. What are the best resources I can use to understand FPGA communication with PC host on the DE2?

Thanks!

altera_forum · Answer

You can use:

- JTAG UART (low performance but very simple with NIOS and Altera IP)

- Gigabit Ethernet (very difficult, require understanding of timings, etc.)

or for good performance (40MByte/s) you can add an external USB to FIFO module like UM232H to exploit USB 2.0 performance. This require some work.

A simpler way is to add an external USB to UART external module (typ 115.200 bps/s).

altera_forum · Answer

Thanks for the suggestions. Performance isn't a concern yet, so JTAG UART will also work for me. But so far all I've been able to use it for is to receive character data from NIOS II on a terminal. I want to be able to write a C/C++ program that will transfer the bit-array of the image to the FPGA. How can I accomplish this with JTAG UART?

Also, are these external modules that you mention (UM232H and USB to UART) additional circuitry or IP Cores that can be added in Qsys?

altera_forum · Answer

It is difficult to interface JTAG UART with a custom C/C++ program. I prefer to use USB to UART module in this case.

External modules are board that you can connect to DE2, like UM232H: http://www.ftdichip.com/support/documents/datasheets/modules/ds_um232h.pdf.

If you use USB to UART like UM232R http://www.ftdichip.com/support/documents/datasheets/modules/ds_um232r.pdf you can use "altera avalon uart" IP core after doing right connections with DE2.

With UM232H you have to write your IP core to interface module to system.

altera_forum · Answer

The DE2-115 board features a 'USB Device' port (J10) for connecting your board, via USB, to a PC (or other host). I don't think you need any additional boards/circuitry to accomplish what you're trying to do.

Look through the 'USB Device' example that comes with the DE2-115 board, covered in section 6.4 of the user manual (http://www.terasic.com.tw/cgi-bin/page/archive_download.pl?language=english&no=502&fid=cd9c7c1feaa2467c58c9aa4cc02131af). This talks you through the example - connecting the board to a PC, installing the relevant driver (for either a Philips ISP1362 or a Cypress CY7C67200, depending on the revision of your DE2-115 board) and running up the software that interacts with the example running on the FPGA. Providing your C/C++ program can interact with the driver, then you'll be able to push and pull data to/from the FPGA in a similar manner to the example.

Cheers,

Alex

altera_forum · Answer

I don't have a DE2 but using CY7C67200 I don't think is so easy but if you have a working example.. just use it. Maybe just using UART with CY7C67200 is simple, you have to check.

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PC to DE2-115 USB Communication

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