Interfacing Compact Flash

[Altera_Forum]

Hi folks, 

I am Pradeep, i am a newbi in FPGA and CPLD designs. i wanted to know how can we interface compact flash with either an FPGA or a CPLD. can you suggest any relevant websites or material to start with.   Sorry if my question is little vague. i am hoping to get a reply soon thanks in advance  Regards Pradeep

[Altera_Forum]

What do you plan to do with it? Do you want to have a soft core CPU too? In that case there is a compact flash controller in SOPC builder, so you could start with some SOPC/Nios tutorials to understand how it works.

[Altera_Forum]

Hello Mr.Daixiwen 

  Thank you very much, our requirement is to just interface compact Flash(can be external device) for data storage which comes(data) after some processing from FPGA/CPLD. thats all its only to store it.   again as you said if it softcore cpu then i guess it requires more complex FPGAs where resources must be large. and i guess it will sit on the Internal of FPGA always. i feel i want an external device (CF) to be connected.  if my understanding of your reply is correct. then can you suggest me more on the way i have to proceed else can you explain me in detail.  i would be thankful to you for your valuable help, i am sorry if my queries are vague.  hope to get a reply soon Thanks in advance Pradeep

[Altera_Forum]

It depends a lot on how you want to store the data on the compact flash. If you want to use a file system, such as FAT, so that you can read back the data on a PC, you will need a CPU. 

The compact flash controller provided by Altera is meant to be used in SOPC builder with a Nios CPU. I think that you could control it directly from custom hardware, but it won't be easy. You can find the controller datasheet here (http://www.altera.com/literature/hb/nios2/qts_qii55005.pdf).

[Altera_Forum]

--- Quote Start ---  If you want to use a file system, such as FAT, so that you can read back the data on a PC, you will need a CPU.  --- Quote End ---  It's the regular way, but not absolutely required, in my opinion. You can also think of a low-level storage, that is compatible with FAT. Of course, some restrictions apply. The most basic method would assign the full media storage to a single continuous file. FAT management on the CPLD side reduces to determining the file's relative sector 0 address in this case.  Regarding CF specific handling, usually true IDE mode is utilized, which is identical to accessing an ATA/IDE hard disk. t13.org has the respective documents. There have been also good OEM CF manuals from Sandisk, describing the protocol in detail.