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Subject: Re: SD Card BUS royalties on a new hardware

Re: SD Card BUS royalties on a new hardware

From: uhmgawa <>
Date: Thu, 09 Apr 2009 09:23:09 -0400

Casainho wrote:
> Hello :-)
> We are working on Lyre project, a Free/Open hardware audio player
> (DAP) and recorder, for use with RockBox firmware.
> We want to boot our ARM9 from SD Card, but we would like to avoid the
> need to pay royalties for using the SD BUS for communicate with card.
> Does anyone knows if this ids true?
>> I think the royalties for the SD Bus are payed by the IC
>> manufacturer.
> Or the manufacturer should pay the royalties? in this case, us, before
> selling the hardware? - we pretend to assembly and sell on Ebay...

IIRC the licensing kicks in at the point a manufacturer
uses the SD logo to advertise their device as SD compliant.
But IANAL and things may have changed since I last looked at
this so you'll need to do some legwork to verify your legal
obligations relative to your situation. Start here:

If you are adding an SD host controller to your device (or
paying for the same integrated into the SoC) it seems odd
not to use the controller -- if for nothing else than to
offload the CPU.

That said you could get by without a controller at audio
bit rates by talking to an SD card in SPI mode. This is
bit serial and only yields 25% of the theoretical maximum
bandwidth available in 4-bit SD mode. But it is cheap
and more than sufficient to transfer audio data to/from
the card. If you don't have a SPI controller you could
even bit bang an interface assuming you have sufficient
CPU bandwidth available.

Received on 2009-04-09

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