Forum Discussion
Honored ContributorHow to use Compact Flash in eCos?
Hi. I'm having problems accessing the compact flash card in eCos. I tried a program that mount the filesystem to / and write a file to it. But the program hangs when I try to open a file. I have run the cf_ide_test that comes with the compact flash ip from this forum. The card is recognised properly. I have also tried to run the fileio1.c test program that is in eCos. I get a -1 error when it tries to mount the FAT fs that's on the CF card. I can read and write to and from it in Windows. It's a brand new card, Kingston Elite Pro High Speed 512 MB.
I have read that I need to remove and insert the card again in some cases. I have tried this, but it does not work. Does anyone have some tip to what I might do? Ole17 Replies
Altera_ForumThe most common cause of error when accessing compact flash from eCos is with using the correct device name. If you have called your device "my_cf" in sopc builder, then you would normally need to use the device name: "/dev/my_cfa/1" (Note the extra "a") in the call to mount(). However it is possible that you have a compact flash card which does not contain a master boot record, particularly if you have had to reformat it after running the cf_ide_test's. In this case you should access the device as "/dev/my_cfa/0".
- Altera_Forum
I have called the compact flash component for cf in SOPC. I have tried to access /dev/cfa/1, /dev/cfa/0, /dev/cfb/0 and /dev/cfb/1. No luck. I just get these errors:
I have made my eCos library with JFFS2 also, could there be a confilct there? I can't see how that might be. I also get this error when I try to access the CF-card that came with the Nios Development Kit. Any ideas? Ole<FAIL>: mount() returned -1 Unknown error <FAIL>: chdir() returned -1 No such entity - Altera_Forum
One other important thing to be aware of is that the compact flash and LCD share pins on the Nios II development boards. If you want to access compact flash, you need to ensure that the LCD is not connected to the board. It doesn't sound like this is your problem, since you were able to access the compact flash using other software.
To help debug the problem, you could enable the debug macros in altera_avalon_cf.c and disk.c. The information these produce may help shed light on the problem. I wouldn't expect JFFS2 to cause any issues. However to be certain that it's not something like that which is causing things to come unstuck, I'd recommend that you create a new project in configtool and follow the steps outlined in the getting stated guide, i.e. just add in the packages listed there. Hopefully that'll get you to a working system, and help you diagnose the problem that you've currently got. - Altera_Forum
I think I have found out what the problem was. But not how to solve it. When I use program_flash to program the flash with my program, and the upload the .sof file again from Quartus, then compact flash don't start. But when I use Nios IDE to upload the program into RAM, then the compact flash component starts and I can read and write from the cf. What could be wrong here? I really want to have the hardware design and program in flash so it starts up when I turn on the dev. kit. How do I do this?
Ole - Altera_Forum
Did you get any further with this?
I've just tried it on a modified version of the standard 1c20 example on a 1c20 dev. board, and I've been able to succesfully access the compact flash even when booting from flash. One thing that I'm doing different from you is that I did this using the pending 5.0 release of the Nios II kit/eCos. However I'm not aware of anything that has changed that would relate to your problem. If you have no other ideas, then you may want to try this again with version 5.0 of Quartus/the Nios II kit/eCos when they are released (which will be soon). - Altera_Forum
I get it to work succesfully when I run it from Nios IDE. We haven't had any need for it to boot from flash lately ,but I will look into it later.
- Altera_Forum
I have tried some more from flash now. One of the problems is that the compact flash isn't power cycled I think. When I run it from flash I can't mount the compact flash. When I run it from Nios IDE, I just take out the card and insert it again and it works.
A couple of other issues: What kind of performance have you got with reading from and writing to the compact flash? With the compact flash card I'm using I should be able to get up to 8 MB/s write speed. I get nowhere near this. I need to have 512 kbit/s writing speed, but I can't get this either. This is used in a datalogger, so I write a couple of bytes at the time. Actually 2 bytes * 8 channels * 4 kHz = 64 kB/s. I basically have a loop that write 2 byte to the spi and read 2 bytes from it. The spi slave is a ADC that can deliever 125 ksamples/s so it is not the bottelneck I think. These 2 bytes are written to a file. Is the fprintf function too slow to make this work? Is there any way to speed this up? How many files can you have open? I have seen the setting in nios2configtool and it is set to 16 files. But when I try to open 4 files and writing to them, the program just hangs. I would like to have 8 files open and writing to each of them a stream of 8 kB/s. I don't feel this is such a large stream of data, but the program just don't work. I use only 1MB of RAM, but I didn't think that could have anything to do with it. A couple of no-so-related issues: Sometimes when I run the program from Nios IDE and out on the dev. kit, the program runs once, and after it is finished, it runs a second time. The realtime clock just keeps ticking a the second run. How do I get rid of this? I run eCos from ROMRAM and I have tried to get around the performance problem described above by writing the samples to a array and then flushing it to the disk. But I can't seem to be able to get the program functioning with a array of 8000 unsigned chars and above. I would like to have 32000 cyg_uint16 preferably, but this doesn't seem to work. I thought I had enough RAM with 1 MB of it, but maybe I should use the 16 MB more that I could access? Ole - Altera_Forum
Your multiple file descriptor problem may be due to re-entrancy. Under eCos, if you try and access the same device simultaneously from multiple threads - you can run into re-entrancy issues. If you are trying to read/write multiple files from different threads at the same time, then you will need to protect the filesystem accesses with a semaphore (or similar) to ensure that the file system does not become corrupted.
With your clock problem, how are you reststarting your code? If you are just brancing back to _start, then you need to make sure that you disable interrupts first. - Altera_Forum
I have just used a standard main() as my program and none threads. I just want the program to run main() and then quit, but usually it starts again a second time.
Just before I read this I tried to use a cyg_uint16 array of 16000 elements and the program can't deal with this. It runs through a couple of printfs and then restarts again. It does this as long as I has bothered to look at it. I does the same under debug. Does it run out of memory? Ole - Altera_Forum
Could be. You can use nios2-elf-size from the comand line to see how much space your elf file requires.
