alt_read_flash()

Thanks! No, it is a good explanation! i will give it a try and if cant, i will leave a msg here again.

Flash is structured not as one large memory but as 1-N regions and each region has 1-N blocks of a paticular size. You can not usually erase just a single byte of flash, so you have to erase the whole block, and then make any changes you need. I know, poor explanation, but google may have a better one, or altera. Either way, you have to take that into account when making a change as you may inadvertently corrupt part of a block if you try and do a partial write. But, per your other thread, if you are just doing a single write then reading back and it is failing that should not be a corruption problem. But, try only writing a block at a time, and looping until you have written all of your data. The code to get the block size is above.

yes, i tried for smaller value n it works fine. i dont quite understand regarding writing in block. please help. sorry, i am new. thanks!

What is the error code? Have you tried writing a smaller value? is there a boundry that it appears to not write on? In all my use of it i write only block_size chunks at a time. Don't know if you have to do that or not, but all my code does. So, you would have to read the regions data structure, which

alt_flash_fd* fd;
int number_of_regions;
flash_region *regions;
    fd = alt_flash_open_dev(flashName);
    if (!fd)
        return -EACCES;
    retval = alt_get_flash_info(fd, &regions, &number_of_regions);
    if (retval) {
        alt_flash_close_dev(fd);
        return errno;
    }

my code is here: http://www.alteraforum.com/forum/showthread.php?t=28345

Yes, i put that before but the return value for alt_write_flash is an error. cannot write.

1048576, or 0x100000

Hi, mmTsuchi. I am transferring 1MB (1 Mega Byte) of data into flash. I am using alt_write_flash. So, what should be the length in alt_write_flash. pls help. I have been debugging the whole day but still cannot understand. Thanks!

Correct. You write however many bytes you would like to read out in that field. You can look at some of the memtest examples for their usage of it as well.