Flash EPCS access problem

[Altera_Forum]

Hi, 

 I&#39;m trying to write my FPGA configuration file on its EPCS16 flash using Nios processor. The final goal is to use Uart/Usb/Ethernet communication to download the FPGA configuration file on the board. I have implemented an EPCS_Controller on my Nios CPU using SOPC builder, and I&#39;m using &#39;alt_flash_dev&#39; drivers to access to it. I success to read flash datas. But I have some problems concerning write access : I can&#39;t write a block entirely (65536 bytes, I don&#39;t have enough memory to store such amount of datas), so I would like to write only part of a block, like this way :   my_epcs = alt_flash_open_dev(epcs_controller_name);  if(my_epcs) {  printf ("epcs opened successfully!");  ptr = 0;  while (ptr<3146000) { // fichier 3mo maxi  my_data = .. // store 0x2000 datas  ret_code = alt_write_flash(my_epcs, ptr, my_data, 0x2000);  ptr = ptr + 0x2000;  }  alt_flash_close_dev(my_epcs);  }  The problem is that each access with &#39;alt_write_flash&#39; function seems to erase the entire block/sector of the flash (which represent 0x10000 datas). Is there a solution to my problem ?  Thanks,  Jérôme

[Altera_Forum]

Hi Jérôme, 

 > I can&#39;t write a block entirely (65536 bytes, I don&#39;t have enough memory to store such amount of > datas), so I would like to write only part of a block,  You can write as little as you like -- but no more than the page size.  > The problem is that each access with &#39;alt_write_flash&#39; function seems to erase the entire > block/sector of the flash  Correct. You can either erase a single sector, or the entire device. There&#39;s no way to erase anything smaller than a sector.  > Is there a solution to my problem ?  If you need to preserve some data in the sector, you need to: read--modify--erase sector--write sector. If you don&#39;t have enough memory (RAM) to read an entire sector, you&#39;ll need to be creative. You could try reserving a sector to hold a copy of the original sector while you perform the update. It&#39;s very not pretty -- but it can work.  Regards, --Scott

[Altera_Forum]

--- Quote Start ---  originally posted by jérôme@Apr 28 2006, 04:19 AM the problem is that each access with &#39;alt_write_flash&#39;[/b] function seems to erase the entire block/sector of the flash (which represent 0x10000 datas). Is there a solution to my problem ?  Thanks,  Jérôme <div align='right'><{post_snapback}> (index.php?act=findpost&pid=14815)  --- Quote End ---  [/b]  --- Quote End ---    This is the nature of using most any flash device.  For your situation, it makes sense to use the alt_write_flash_block() function. It won&#39;t automatically erase the flash....like alt_write_flash() does. In this way you could write to the flash in whatever data size you want and detect when a sector erase is necessary yourself.  Something like the following should work if you implement it in a loop passing new "data" in with each pass:  if(new_flash_block != current_flash_block)    {      printf("\nFlash Block %d", new_flash_block);      alt_erase_flash_block(fd, (new_flash_block * regions->block_size),                                      regions->block_size);      current_flash_block = new_flash_block;    }    alt_write_flash_block(fd, (current_flash_block * regions->block_size),                                   target_addr, data, data_len);  Cheers,  - slacker