sd card problem / GPIO drive

RE: sd card problem / GPIO drive

haakonsh — Tue, 25 Sep 2018 11:05:31 GMT

I can take a look at your layout if you want. You can set this case as 'private' and anything you post will be confidential from that point on.

Do you have datasheets for the SD cards?

RE: sd card problem / GPIO drive

Michal — Tue, 25 Sep 2018 09:09:59 GMT

Yes.

Symptoms are that (usually) card is able to initilize and prints capacity but then fails on mounting. I tested 3 different cards and on my pcb none of these was working. When I am trying with nrf52 dk and SD slot then usually 2 working and only one fails with the same behaviour (fail on mounting, however sometimes it works).

RE: sd card problem / GPIO drive

haakonsh — Mon, 24 Sep 2018 11:02:16 GMT

Do you have more information on the nature of your problem, like what are the actual symptoms, how many different cards have you tried and how many of the works?

RE: sd card problem / GPIO drive

Michal — Sat, 22 Sep 2018 08:52:07 GMT

Thank you :) I tried applying H0H1 to all lines but did not get better result in compare to what you proposed in previous thread.

RE: sd card problem / GPIO drive

hmolesworth — Sat, 22 Sep 2018 00:55:53 GMT

/CS should probably be H0H1 as well (its not mentioned above) ..

RE: sd card problem / GPIO drive

haakonsh — Fri, 21 Sep 2018 13:35:00 GMT

"I am wondering if because of too weak drive of gpios nrf may not be able to drive some of SD cards over SPI?"
One way to test that hypothesis is to drive the I/O lines by external MOSFETs.

"Or may it be that current peak caused by SD card have introduced some noise to power lines and to SPI lines?"
Try decoupling the SD card supply with 4,7µF in parallell with 100nF, and 1nF.

RE: sd card problem / GPIO drive

Michal — Fri, 21 Sep 2018 12:54:10 GMT

Thanks, I tried it all. I lowered CLK speed to lowest and did not get better results. Also I was checking lines with logic analyzer and I saw that sometimes lines go high or low for microseconds when they should not.

I am wondering if because of too weak drive of gpios nrf may not be able to drive some of SD cards over SPI?

RE: sd card problem / GPIO drive

haakonsh — Fri, 21 Sep 2018 12:35:22 GMT

I'd try to lower the CLK speed incrementally and see if that helps. I would also scope the IO lines with both a digital analyzer and a regular oscilloscope to see if there's something out of place.