SD Card 4 bit mode license

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slash2

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I need to use the fast 4-bit mode on a Teensy 4.0 and the example code seems to work fine. However, I was under the impression that the 4 bit mode was regulated by the SD Association and required a license. Is the Arduino fast SD code different somehow so that it skirts around this requirement?

I did try to search this in the forum, but did not find any previous topics covering it.
 
This is really a question for the SD Association. I can't give you "legal advice" and I certainly can't speak for the SD Association. But I can give you some facts.

PJRC has not paid anything to the SD Association.

I'm pretty sure Bill Greiman (author of the SdFat library) probably has not either.

NXP publishes their own code SDIO code as part of their SDK, which anyone can download for free (website registration might be required). You might ask NXP. I have not seen any documentation from NXP about licensing required, and I have read a lot of their documentation!

I believe all the SDIO commands SdFat uses were documented in the original SD Memory Card Specification (version 1.0) published in March 2000. Much of the tech (definitely 4 bit mode) came from earlier MMC cards, which were sold as early as 1997.

Again, this is not legal advice, but generally patent rights last 20 or 21 years. However, before late-2000 a practice known as submarine patent was possible, so the situation can be complicated. Since the original SDIO spec is now more than 24 years old and MMC is even older, it's difficult to imagine patent rights could still apply. There are other aspects of IP law than patents, so your best approach would be to consult with an IP attorney.

But this is really a question for the SD Association. If anyone gives you a clear answer, I hope you'll share.
 
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Thanks Paul,
This is an important issue for me as I am part of a team that builds custom lab equipment for scientific research (we have used many many Teensys over the years). We have a mandate to open source our designs. A license requirement would seriously hamper this project as I would assume each outside research institute that builds our design would need to get a license. We do have a legal department - maybe I can get them to look into it. I will pursue this and report back. Of course the last thing I would want is for the SD Association to decide to go after existing code.
 
Unfortunately, the SD specifications say:
Notice is also hereby provided that notwithstanding any
rights granted by the Terms, any implementation of the Simplified Specifications or any portions thereof may
require a separate license from the SDA, SD Group, SD-3C, LLC or other third parties.
Click to expand...

What triggers a license requirement? I don't know. Maybe it is hiding in one of those documents or somewhere else on the web site.
But people have been writing code to these specs for a couple of decades.
 
Yeah, I ran across that too...
I also saw a mention somewhere online that one only had to have a license if they wanted to use the SD Card logo, etc.
I'm trying to see if our legal group can look into it.
 
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