Raspberry Pi write cycles

[Chuck Guzis]

On 8/14/19 8:04 PM, dwight via cctalk wrote:
> Some of the newer larger SD cards use a different write voltage than 3.3V. There is a ways of asking the card what voltage it likes during the init.
> Using the full 3.3V on these parts can damage them.
> They are all required to init with 3.3V but the voltage for writing may be different.
> I've only played with the ones smaller than 2GB. But any time I get a new one, I check the voltage.
> Dwight

Does the Pi use the spi interface or the SD 4 bit interface?  The latter
is faster and I'd expect the Pi to use it.

I've modified the bootloader on my OPi systems to use USB pen drives.
Seems to work just fine.

FWIW, SD, SDHC and SDXC cards work fine (per spec) at 3.3V.   I use 16
and 32GB ones at 3.3V and they work flawlessly.  You *can* command SDHC
and SDXC to 1.8V, but the conversation is usually started at 3.3V.

--Chuck