1. Home
  2. Embedded Programming
  3. SD card in 4-bit mode

SD card in 4-bit mode

Hello all,

I'm in a need for the higher transfer speeds with SD card, I'm running the card at 25 MHz via SPI and it works well, but I still need higher transfer speed.

I would like to use the 4-bit (parallel) mode of the communication with the SD card, and I know that to do that one has to be the member of some SD association and that only SPI mode is free... But since this is just a hobby project for myself, I wouldn't mind breaking a small copyright for my project or experiments.

So what is the problem? Is the 4-bit mode documented on the web, but you can't use it legaly without paying the SD association, or there is no public documentation and you need to pay a fee to get that documentation?

Regards, Jookie

Reply to
Jookie
Loading thread data ...

Nowadays you can download a simplified SD card spec for free, which should be enough to use the cards in 4-bit mode. The spec omits some hardware details, I guess so that you can't implement a controller without a license.

If you need to implement the controller yourself, you can now download the complete MMC system specification for free. AFAIK the two standards aren't 100% compatible, at least when it comes to the high capacity modes. Hopefully someone will correct me on that if I'm wrong.

-a

Reply to
Anders.Montonen

you set the the bus width via a few commands, I think sandiks docos have full details:

formatting link

Reply to
MisterE

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.