eepromflashfpgavhdl
For applications that require design on FPGA which shall make use of several image files, sound files or other forms of files, can they be simply included in the FPGA design configuration file? In any case if these things are stored in an external flash or EEPROM memory, is there a reference design that:
Firstly, hex file are text files. Secondly, I have found it easier to write scripts to parse the external files in VHDL, than to use VHDLs limited text processing capabilities.
Another option you have is to use some of the RAM of the FPGA. You can configure the RAM using your hex file. This is perfect if you are testing internal memory.
A cautionary note: text IO is not supported by many IDEs for synthesis, even though it is in the VHDL spec. I once lost a few hours parsing text in VHDL only to find it will not synthesize.
Edit I know this is not an answer to the original question, but I wanted to point out that there are better tools for the task. You can save yourself a lot of headaches by using a parsing library.
Loading directly from an external ram is probably going to be more trouble than its worth, it may require hacking, I have not tried this and probably never will, I believe it is possible. Here we go:
You need to get the compiled code using one of the methods listed in the "Generic Nios II Booting Methods User Guide" document I think the .hex file looks the most promising.
Load the memory from the JTAG, this document describes how to write to memory and other avalon MM devices.
Point your reset memory vector in the NOIS processor to the boot address in your external ram.
Then your going to have to trigger a reset without resetting the external ram. This is the hack part, since I don't know your setup, your going to have to do this.
Good luck, sounds like a fun project. I'd try it out if I had the time, maybe I will someday (I've also ran into this problem, for me it was much less time consuming and cheaper to upgrade the FPGA, in fact if your developing you should almost always use the biggest fpga possible)
Here is another cool article on booting from an external processor
Best Answer
Well, it really depends on how big your data is, how often you need access to it, and what sort of bandwidth you need. There is no good 'one size fits all' solution to this.
For small data, on-FPGA block RAM is a good option. The on-chip block RAM can be initialized from the bitstream data, so it can be used as a ROM. The on-chip location of the block RAM also provides the highest possible bandwidth. No external pins are required. However, the block RAM is very limited in size, so don't waste this resource unless absolutely necessary. It is also not really possible for the FPGA to edit the ROM entries as it would have to edit the initialization data for the block RAM in the bitstream (a far from trivial operation), so they are really only useful for constant storage or volatile storage.
Now, as for external nonvolatile memory, this is a bit more difficult. There are many different types of memory that could be used, with many different protocols. This could range from a simple I2C or SPI flash chip or SD card, to a parallel NOR flash or NAND flash, to an SSD or HDD connected via SATA or PATA, to accessing a file server or SAN over Ethernet. What makes sense depends on how big your data is, the access latency required, and the access bandwidth required. Connections over I2C or SPI will be very slow, perhaps up to a couple of MB per second. However, the protocols are very simple. So if you just need to stream 48 ksps audio data, this could be a good option. However, this will not work for something that requires a lot of bandwidth like full HD video. For something like that, you would need an interface with a lot more bandwidth. This is where the engineering can get a bit challenging - large, fast storage is not easy to interface with. One option might be to bring up a SATA interface and connect a large SSD. There will be some latency requesting the data, but you'll be able to stream many gigabytes of data off of the device at several hundred Mbps.
Also, don't forget that you will probably need some way to write to the nonvolatile storage as well. If this needs to be done at high bandwidth, then that means you will need some other interface to the outside world. Ethernet and USB 3 are reasonable options.