SD snd SDHC card differences

Regards, Chris Burrows

Armaide: ARM Oberon-07 Development System

Yes, but what are the technical "executive summary" between the two standards?

What are the physical differences?

What are the protocol differences?

Could a software derived SD controller be re-written if the software and hardware was fast enough meet SDHC speed requirements?

I ask these questions becuase

doesn't go in to protocol detail - as I asked in my original question.

Joe

The executive summary is a PowerPoint presentation that says "SDHC newer, different logo fees apply". Right under that is a second bullet point that says "SDXC obsoletes SDHC".

Mainly addressing mode changes so that larger cards can be supported.

Yes in general an SD implementation can be upgraded to SDHC by software only.

Also microSD to SD adapters are passive, so yes they are identical apart from form factor (no write protect switch on microSD)

Great thanks.

I see the short form version of the SD specification has been released but not the SDHC, as I could not find it anywhere.

Joe

Un bel giorno Joe G (Home) digitò:

The only remarkable difference that I know is that the support of SPI mode (which is very handy for small microprocessors applications) is only optional for microSD.

This is true but in practice I have never seen one that took advantage of this. They appear to be identical dice in different packages. Some of the Chinese SDHC cards I've bought are in fact bonded onto a PCB that can be cut in one place as microSD and one place as SD form factor :)

SD (all flavors) is a buyware spec, gotta pay to join the club. But of course you can find everything you need by browsing around the Internet, it's just a matter of collating it all.

Un bel giorno larwe digitò:

Then I must be very unlucky, I tried with a single microSD and it didn't work. :)

I don't remember the brand now. It could be Sandisk but I may be mistaken.

mode

SanDisk MicroSD does support SPI mode. I was not able to get SPI=20 mode to work reliably with a Kingston MicroSD.

--Gene

I am using a Lexar 2GB microSD on this board:

don