Converting generic memory into an SD interface

[rollerblade]

Hi there,

I'm doing a project for my professor, which needs creating a memory interface between a generic virage memory and an SD port. So in essence, I want to make a memory on a digital chip appear as an SD memory to computer.

How feasible is this? Since I do not have much experience with such interfaces, your input would be greatly appreciated. I was reading about the uALFAT Chipset, but couldn't find information whether it can perform the task I've explained above.   

Please let me know.

Thanks,
Shrey

[SupportAdmin]

If you want to simulate SD card on memory then I doubt even your processor can do it!! If you want to simulate a USB memory reader then use a dsPIC and use the code provided from microchip

[rollerblade]

Thanks for your swift reply!

So do you mean to say that such an interface is not possible? If not, then what exactly makes it non-implementable? Sorry if the answer is obvious, but I'm not a programmer. I'm an analog designer, and this digital implementation is something totally new to me.

Also if I had to implement this using a USB interface, can dsPIC communicate with a PC through a USB connection?
I would be glad if you can tell me where exactly dsPIC resides in such a system, since I am not getting the entire picture here...

Thanks again.

--Shrey

[SupportAdmin]

SD interface required VHDL programming in an FPGA. Doing this is very difficult even for a professional with 10 year experience I think.

Now, USB is easier because the USB hardware is already implemented. If I knew exactly what kind of experience you have and what exactly you are trying to do then I can give you a better answer. You should go back to your professor and get better idea of what he wants

[rollerblade]

Now that's the problem... My professor thinks an SD interace is possible, and he needs it because then he can access things on his i-phone. 

However, if this is too much work, I might end up going with USB. I can probably convince him to do that.
Regarding my experience, I've had some experience with DE-2 board from altera, which can implement such an interface. But when I used it last time (>3 years ago), it was for totally different application, and not for memory interfaces. (In short, i'm rookie when it comes with such things. hence looking for some simpler solution)

Having said that, I'm wondering how dsPIC will be useful here?
One way I can visualize is

Memory -----> (SPI) ---> dsPIC ---> (USB) ---> PC

Is that something you were sugesting in your first message?

How easy is this approach?

I would highly appreciate your feedback, since you're experienced in such things.

Thanks again,
Shrey

[SupportAdmin]

Is there an SD on iPhone?! I am do not think there is SD on it!
If you know altera and VHDL/Verlog then you are closer from implementing an SD simulator but I doubt it is easy.
One last question, why do you want *raw memory* interface to connect to a PC? Again, once I know the application then I can tell you what to do!

Using our USBizi, many companies are recording data to SD (or micro SD) cards as a means of data logging then they plug in USBizi to a PC which simulates a card reader so the PC can then read the logged data/files. This is identical to how digital cameras work...they save files on SD cards but if they plugged into a PC they become a card reader

When logging:
inputs(analog/digital) ---> USBizi --->internal file system--->SD card
When plugged to a PC
SD card --->USBizi --->USB cable--->PC

[rollerblade]

ah. That's very interesting. This can have some good application in my case.

The reason we're implementing this on a raw memory is due to a project in our lab. There's a custom chip (made by a PhD student) which collects data for an experiment. This data is first sent through an A/D converter before dumping into this memory. We then read this using a serial interface into computer. However, this whole thing is too cumbersome to move from place to place, and we need a highly portable solution. If it could be read in SD fashion using a controller (or a USB, if that's easier), it can be put into many places for direct data access.

One added reason for using RAW memory is that it will be part of this chip, meaning a single die silicon piece will contain Data Sensing + A/D conversion + Memory. My part comes after the A/D conversion. Meaning I can decide what type of A/D converter we need for this one, since I'll be the one who reads from the memory.

So what's the easiest way to access such a memory to a computer? (I hope this is the detail you needed).
USBizi sounds very interesting, and I believe it will have to reside after A/D conversion.

Your input is greatly appreciated.

Thanks!
Shrey

[SupportAdmin]

The easiest way is to implement a serial port to a PC. USBizi (.NET Micro Framework)will open many new doors for your design
You (and your friends/professors) should take a look at this new great technology....spend sometime reading this free ebook http://www.ghielectronics.com/forum/index.php/topic,2408.0.html