nRF9161 DK SPI Flash example

[nrao32]

I'm looking for a beginner's guide to setting up external flash on the nRF9161 DK. I saw nRF Cloud Multi-service as an example, but its docs did not explain what was needed hardware-wise to set up the external flash memory (I found this). Basically, I have a spare Adafruit SPI Flash SD Card XTSD 4GB, and I'm looking to connect it to the DK if possible. I assume I need to modify the board overlay but I'm not sure where to go from here. Where are the pins for gd25wb256 in the sample defined? 

[Hakon]

It is taking some time to port this sample to nrf9161, but interfacing the SD card with SPI works now. You can add the overlay to the sample and build with prj_blk.conf

&spi3 {
    gd25wb256: gd25wb256e3ir@1 {
        status = "disabled";
    };
    sdhc0: sdhc@0 {
            compatible = "zephyr,sdhc-spi-slot";
            reg = <0>;
            status = "okay";
            mmc {
                compatible = "zephyr,sdmmc-disk";
                status = "okay";
            };
            spi-max-frequency = <1000000>;
    };
};

then use the arduino pins for SPI. You can just ask if you need more help after this. I will let you know when I'm done with the sample.

[nrao32]

Perfect timing! Thank you, Hakon! Can you please let me know what you mean by "arduino pins for SPI"? Which pins are those on the board?

[Hakon]

You can check this https://docs.nordicsemi.com/bundle/ug_nrf9161_dk/page/UG/nrf91_DK/hw_description/external_memory.html

But use P0.10 for CS pin instead.

[nrao32]

Great. I will give this a go. I'm not sure if I'll be able to reformat this particular SD card chip I've got, as it comes preformatted with FAT fs, which seems to be a bit more complex to set up based on the nRF fatfs sample, however I will try. Thanks again!

[nrao32]

Hi Hakon, can you please let me know what SD card module / SD card you are using for your test? I just get the following error when I run the sample:

*** Booting nRF Connect SDK v2.9.0-7787b2649840 ***
*** Using Zephyr OS v3.7.99-1f8f3dc29142 ***
Sample program to r/w files on littlefs
I: LittleFS version 2.9, disk version 2.1
I: Card does not support CMD8, assuming legacy card
E: Storage init ERROR!
E: fs mount error (-134)

I've tried several different SD card modules and different SD cards. I tried the littlefs sample (formatted the SD card with lfs tool) and the fat_fs sample (formatted the SD card as FAT32). I have been trying for days. Any pointers would be appreciated! Thanks again.

[Hakon]

nrao32 said:

I: Card does not support CMD8, assuming legacy card

Yes, this card is probably not SDHC compatible. I had the same issue, so I changed the SD card to a newer one. I use a SanDisk Ultra 16 GB SD card.

[nrao32]

No dice. Bought this:
https://www.amazon.com/dp/B0D3WY8DR6

... which explicitly states microSDHC support, and I still get the same "Card does not support CMD8, assuming legacy card" -- I tried variations of that overlay file like:

&spi3 {
    gd25wb256: gd25wb256e3ir@1 {
        status = "disabled";
    };
    
    status = "okay";
    pinctrl-0 = <&spi3_default>;
    pinctrl-1 = <&spi3_sleep>;
    pinctrl-names = "default", "sleep";
    cs-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
    
    sdhc0: sdhc@0 {
        compatible = "zephyr,sdhc-spi-slot";
        reg = <0>;
        status = "okay";
        mmc {
            compatible = "zephyr,sdmmc-disk";
            status = "okay";
        };
        spi-max-frequency = <1000000>;
    };
};

I tried fiddling with the spi-max-frequency as well. Oddly, it works with my nRF9160 DK, but I can't for the life of me get this working on the 9161.