James Newton, Host wrote:
> BillW said:
>   
>> I've been adding miniSD cards to ARM-based media players recently:
>> http://www.elinux.org/wiki/JuiceBoxMMCHack
>>     
>
> Cool!
>
>   
>> There's a problem with SD cards in general in that they're 
>> heavily licensed, and in theory you can't get specs, or use 
>> them, or buy sockets for them, without paying $$$$ in 
>> SD-assoc membership fees.
>>     
>
> Huh? My understanding was that the card /makers/ had to pay the fees not the
> card /users/. Are they seriously saying that if you make a device that uses
> their product (and therefore sells more of their product) that you have to
> pay them a fee? The sockets are available from a number of sources. The
> piclist.com page references some from mouser and jameco.
>
>   
>> (people get around this by using them in MMC/SPI mode, but 
>> there's some question as to whether SD cards in general, and 
>> especially the newer packages, always support that.)  
>>     
>
>   
No, that was a few years ago, and revolved around Sony's Memory stick 
products. The SD cards
info is available everywhere free.

> Huh? Where did you hear that doubt expressed? Everything I have read says
> that the serial modes are required...
>
>   
>> (Sparkfun apparently sells microSD sockets.  And someone 
>> pointed out that if you're careful you can use the "adaptors" 
>> that usually come with the microSD cards as
>> sockets...)
>>     
>
> With sockets at a few dollars there is no need, but if you get the adapters
> for free, it's a cool hack.
>
>   
>> MicroSD and miniSD are still somewhat more expensive than 
>> full-sized SD, and IMHO, the "sweet point" for cheap microSD 
>> cards is almost too large for typical embedded use.  Gimme 
>> those $4 32M (full sized) MMC cards instead...
>>     
>
> Good point. This is probably my main concern: In 5 years, will you be able
> to purchase a 1GB microSD card or will they all be 20GB or more?
>
> On the other hand, I wonder if you will be able to purchase any size MMC
> card. They don't seem to have that large an install base...
>   
The MMC card is just an SD card with an unlock feature missing, which 
also drops a pin.

--Bob
> ---
> James.
>  
>
>   

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