fs_mount fatfs in RAM not working -- "fs mount error (-5)"

[douglas.malnati]

Hi, I'm using NCS v2 building on VSCode and failing to mount a RAM-backed fatfs instance.

I looked at the code for the usb mass storage example (link) for the code.

The error I get is: [00:00:00.770,233] <err> fs: fs_mount: fs mount error (-5)

My prj.conf is:

CONFIG_DISK_DRIVER_RAM=y
CONFIG_FILE_SYSTEM=y
CONFIG_FAT_FILESYSTEM_ELM=y
CONFIG_DISK_RAM_VOLUME_SIZE=32

My code is:

static void setup_disk(void)
{
    static FATFS fat_fs;
    static struct fs_mount_t fs_mnt;
    memset(&fat_fs, 0, sizeof(fat_fs));
    memset(&fs_mnt, 0, sizeof(fs_mnt));

    fs_mnt.type = FS_FATFS;
    fs_mnt.fs_data = &fat_fs;
    fs_mnt.mnt_point = "/RAM:";

    int rc = fs_mount(&fs_mnt);
}

Can you help me understand what I need to do to get this to work?

Thanks.

[Hakon]

Hello,

are you using a DK? What is the hardware setup? Do you have any overlay files?

[douglas.malnati]

Hi, it's not a DK, it's a custom board.  The overlay file is from the adafruit_feather_nrf52840, which my project is forked from (since I started development on that board and later moved to a custom board).  I've tweaked some UART settings and pin mappings, but nothing else.

Thanks.

[Hakon]

Can I see what you have done in the overlay file?

[douglas.malnati]

&pinctrl {
	uart0_custom: uart0 {
		group1 {
			// psels = <NRF_PSEL(UART_TX, 0, 25)>,  // old custom board
			psels = <NRF_PSEL(UART_TX, 0, 16)>,   // new custom board
                    <NRF_PSEL(UART_RX, 0, 24)>;
		};
	};
};


&uart0 {
    status = "okay";
    current-speed = <9600>;
    // current-speed = <38400>;
    pinctrl-0 = <&uart0_custom>;
    label = "UART_0";
};

&pinctrl {
	pwm0PinList: pwm0-pin-list {
		group1 {
			psels = <NRF_PSEL(PWM_OUT0, 0, 6)>,
				    <NRF_PSEL(PWM_OUT1, 1, 8)>,
					<NRF_PSEL(PWM_OUT2, 1, 9)>;

		};
	};
};


&pwm0 {
	// enable
	status = "okay";

	// set the pin for given channel
	pinctrl-0 = <&pwm0PinList>;
	pinctrl-names = "default";
};


/ {
	pwm0-channels {
		compatible = "pwm-leds";

		// period specified in ns, so Xms scaled out to ns
		pwm0_0: pwm0-0 {
			pwms = <&pwm0 0 (1 * 1000 * 1000) PWM_POLARITY_NORMAL>;
		};
		pwm0_1: pwm0-1 {
			pwms = <&pwm0 1 (1 * 1000 * 1000) PWM_POLARITY_NORMAL>;
		};
		pwm0_2: pwm0-2 {
			pwms = <&pwm0 2 (1 * 1000 * 1000) PWM_POLARITY_NORMAL>;
		};
	};
};

[Hakon]

The documentation says; "If more than 96KiB are available, FAT files system can be used with a RAM-disk."

Perhaps you should consider changing this line then,

CONFIG_DISK_RAM_VOLUME_SIZE=32