Hi,

I'm using an SD card with MCI/SDIO interface with FatFs.
Everything works fine, I can read files, write files and so on.
Most of this work has been done by Chan (FatFs) and Atmel, so thanks to you guys!

There's just one problem:
I want to write to a file every now and then (f_open, then successive f_write's), but inbetween writes the SD card (actually microSDHC) should sleep automatically to cut power consumption.
But it doesn't, because after one f_write it stays in "data state" (last disk action of f_write is a disk_read), for auto sleep it has to be in "tran state".
I can get it into "tran state" with CMD12, but here comes the problem: I don't know how to get it back into "data state". If I just continue with f_write after CMD12, I get a disk error.

So how can I get f_write to work again from "tran state" / sleep?

Pleeeease help!

Thanks,
IBE

Hi!
The simplest, brute force solution is to reinitialize the card from scratch. That is what I did when wanted a quick solution.

Thanks, I found the solution.

In the Atmel example (which I used for a great part), the function MovetoTranState (or so) sends the stop command (CMD12) to stop continuous transfers and sets the card to "tran" state, but it doesn't reset the Sd-drivers state (pSd->state) variable back to "ready" from read or write. So I just needed to update this function and call it whenever I think the SD should enter auto-sleep. Waking up is done with the next command automatically.