NRF52 SD card example intermittent problem initialising

RE: NRF52 SD card example intermittent problem initialising

Stian Røed Hafskjold — Fri, 08 Mar 2019 11:49:20 GMT

Hi, sorry, I've been out traveling. I'm not really sure what the difference between the module and just connecting the SD card with wires is. Except for suggesting that there's somehow a bad connection. The level converter would amplify the signals even though the voltage is the same. Further testing shows that connecting the wires directly only works if I do not attach a logic analyzer to the MISO pin. If the analyzer is connected, it's not possible to initialize the SD card after a reset. Then I need to power cycle the SD card.

I have a feeling that the capacitance on the MISO pin is too high in order for the SD card to being able to pull it up or down (even though this only applies after a reset, which is weird). I see in your schematics that you have two devices connected to the MISO pin. Can you try to cut the trace to the other device and see what happens?

I have to do some more testing to see what this really is. Sorry for taking so long, but I have some more time to look into this now.

RE: NRF52 SD card example intermittent problem initialising

bgarrood — Mon, 25 Feb 2019 13:50:56 GMT

Hello Stian. I left a message 11 days ago? Would you mind replying? Would be really helpful to confirm what you meant in your message.

Thank you.

RE: NRF52 SD card example intermittent problem initialising

bgarrood — Thu, 14 Feb 2019 06:52:28 GMT

Thank you for testing this Stian.

I do have a ground plane, it just isn't shown in the schematic I sent you.

Great news that you can replicate my problem, but I dont quite understand the difference between your two setups:

When going through the module with voltage regulator and level converter it works as expected, but when you connect the SPI lines directly (bypassing the level converter) it doesnt? Why do you think this is? What is the level converter doing as presumably you have 3.3V on both sides? You suggest a poor connection, but why would this be if the lines are connected directly?

Almost there. Thank you again so much! It really is a massive help.

RE: NRF52 SD card example intermittent problem initialising

Stian Røed Hafskjold — Wed, 13 Feb 2019 21:14:29 GMT

I tested with the SD card I got and it seems to be working fine when running your code. I'm using a module with a 3.3V regulator and level converter for the SPI lines. If I just connect the SD card with wires to the GPIOs of the chip I see some similar (random) symptoms as you mention in the original post. It suddenly stops responding and sometimes I get high current consumption. So this makes me think that what you are seeing is because of bad connection. When looking at your PCB design, I see no ground plane? Without a ground plane or proper ground signal things can get really noisy. You get cross talk between lines, voltage drops etc.

RE: NRF52 SD card example intermittent problem initialising

bgarrood — Mon, 04 Feb 2019 10:53:07 GMT

Hello,

That's great, thank you. I attach pdfs of board layout and schematic. Board pdf is a bit poor, let me know if I can send in any other format. I am using EagleCad for the design.

Cheers

Barney

devzone.nordicsemi.com/.../CB_2D00_015_5F00_3_2D00_BRD.pdf devzone.nordicsemi.com/.../CB_2D00_015_5F00_3_2D00_SCH.pdf

RE: NRF52 SD card example intermittent problem initialising

Stian Røed Hafskjold — Mon, 04 Feb 2019 10:00:58 GMT

Ok, I ordered one now. It will probably be here in a couple of days. Can you please send me the schematics and layout of your board? Thanks

RE: NRF52 SD card example intermittent problem initialising

bgarrood — Fri, 01 Feb 2019 14:54:10 GMT

Hello,

Thank you for the reply.

I am not using a module, I am interfacing the card directly from nRF GPIOs.

The card I am using is a Kingston SDC4/8GBSP (https://www.kingston.com/en/flash/microsd_cards/sdc4)

The sd card adapter is surface-mounted to my board, so not easy to see the responses directly, so hard for me to compare to what you have.

If you were able to try and replicate it would help me out a lot.

Thank you again for your time. Much appreciated!

Many thanks

Barney

RE: NRF52 SD card example intermittent problem initialising

Stian Røed Hafskjold — Thu, 31 Jan 2019 15:18:50 GMT

Sorry, I'm not able to reproduce the behavior here. When I'm running your code it re-initializes just fine, and the current consumption seems to be fine

I'll post the SPI trace, so then you can connect a logic analyzer and see if you get the same response from the SD card

devzone.nordicsemi.com/.../init_2D00_reinit.csv

I'm still worried about the voltage though. The SD card socket module I used here could not handle 3.2V, it had to be 3.3V. Are you using a module, or are you interfacing the SD card directly from the nRF GPIOs? I'm thinking that something goes wrong during uninitialization leading to the high current consumption, and then because of the high current, the voltage drop is too high to re-init, if it's already on the limit.

Are you able to give me some more info about the SD card? A link would be fine. Then I can order one to test here.

RE: NRF52 SD card example intermittent problem initialising

bgarrood — Tue, 29 Jan 2019 12:11:22 GMT

Hello Stian, are you able to give me any suggestions with this? I am still stuck.

Best regards

RE: NRF52 SD card example intermittent problem initialising

bgarrood — Mon, 21 Jan 2019 13:10:02 GMT

Hello. Thank you for the quick response!

I am powering the device with a coin cell. For development (so in the state that I am seeing these problems) I have been using a power supply at 3.2V.

Thank you.

RE: NRF52 SD card example intermittent problem initialising

Stian Røed Hafskjold — Mon, 21 Jan 2019 12:36:01 GMT

Hi, first of all I just want to check that you are powering the SD card properly. What is the voltage, and type of supply you are using? I've seen unstable behavior when the SD card is powered for the nRF5 DK (3V)