Microcontroller SPI mode TO SD card SD mode conversion

[kamiqash]

Hi all,
Uptill now I have only found out people working in either SPI mode to communicate with SD card or in SD mode.
What I want to do is, have microprocessor at one end working in SPI mode, on the other end SD card receives data is SD mode.
The intermediate hardware interfacing these two (microprocessor, SDCARD), is an FPGA.
I need suggestions of how you think I can achieve this goal.

At the moment I have placed five bidirectional buffers in the FPGA, and tried to make a write and read logic in Xilinx. My FPGA knows nothing about what is command or response, it only controls the enables of the bidirectional buffers using a timing diagram.
From the five, four bidirectional buffers are the ioports for parallel data in, parallel data out and the fifth one in connected to the Command pin of SD card.

Thanks in advance.

kamiqash

 

[FvM]

i guess, your objective is speed increment. I wonder however, if the expectable improvement is worth the effort.

Although SD and SPI mode are basically referring to the same command set and data structures, there are some incompatibilities, e.g the read OCR command that's exclusive to SPI mode. It needs to be emulated for a fully transparent conversion. There may be more sticking points.

 

[kamiqash]

Hello FvM,

Yes you are correct. The end result is to increase the speed.

"It needs to be emulated for a fully transparent conversion."
In the above post you mentioned this. I don't fully understand what you mean by this.

Is this project possible when all the exclusive commands have been tackled.

kamiqash

 

[kamiqash]

Hello Every one,

After such a long time my problem remains the same, is the conversion of SPI interface to SD interface possible.
I have a micro-controller which can send data on SPI protocol only, and I want my SD card to read and write on SD protocol. My success is only till simulations. On hardware I have no clue whats going on. Any advice would be appreciated.
Thanx

Kamran