Slow USB MSC transfer speed on nRF5340 with SD card

[Shuhao Dong]

In our design, we wired the SD card in SPI mode on SPI bus 4 wich a maximum SPI frequency of 50 MHz or 25 MHz as these are supported by the SD card. We used FAT32 file system, but later enabled support for exFAT and formated the SD card with exFAT. For internal logging from our device to the SD card, there is no issue. However, when we try to offload the data from SD card to a host machine, we are having an extremely slow transfer speed: When offloading a 10.5 MB binary file, it takes around 420 seconds, which effectively is only 90 KB/s. We have tried both 25 and 50 MHz SPI frequency but the result is very similar.

We are using USB legacy stack with NCS 3.0.2. I attached here our Kconfigs related to USB.

# Configure USB device
CONFIG_USB_DEVICE_STACK=y
CONFIG_USB_DEVICE_PRODUCT="BORUS"
CONFIG_USB_DEVICE_PID=0x0001
CONFIG_USB_DEVICE_VID=0x0001
CONFIG_USB_DRIVER_LOG_LEVEL_ERR=y
CONFIG_USB_DEVICE_LOG_LEVEL_ERR=y
CONFIG_SERIAL=n
CONFIG_USB_CDC_ACM=n
CONFIG_UART_INTERRUPT_DRIVEN=n
CONFIG_UART_LINE_CTRL=n
CONFIG_BOARD_SERIAL_BACKEND_CDC_ACM=n
CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n

# Configure USB device to appear as DFU class
# Configure DFU autoupdate and reset
CONFIG_USB_DFU_CLASS=y
CONFIG_USB_REQUEST_BUFFER_SIZE=128
CONFIG_USB_DFU_ENABLE_UPLOAD=y
CONFIG_USB_DFU_PERMANENT_DOWNLOAD=y
CONFIG_USB_DFU_REBOOT=y
CONFIG_IMG_MANAGER=y
CONFIG_STREAM_FLASH=y
CONFIG_BOOTLOADER_MCUBOOT=y

# Configure file system 
CONFIG_FLASH_MAP=y
CONFIG_FLASH=y
CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_LITTLEFS=n
CONFIG_FAT_FILESYSTEM_ELM=y
CONFIG_FS_FATFS_LFN=y
CONFIG_FS_FATFS_EXFAT=y
CONFIG_FS_LOG_LEVEL_INF=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_MPU_ALLOW_FLASH_WRITE=y
CONFIG_NORDIC_QSPI_NOR=y
CONFIG_NORDIC_QSPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

# Configure mass storage
CONFIG_USB_MASS_STORAGE=y
CONFIG_DISK_ACCESS=y
CONFIG_USB_MASS_STORAGE_LOG_LEVEL_ERR=y
CONFIG_DISK_LOG_LEVEL_DBG=y
CONFIG_DISK_DRIVERS=y
CONFIG_DISK_DRIVER_SDMMC=y
CONFIG_DISK_DRIVER_FLASH=y
CONFIG_MASS_STORAGE_DISK_NAME="SD"

[dejans]

Hi,

Which SD card do you use?

Can you show your SPI related configuration?

You can try to increase the value of CONFIG_SPI_NRFX_RAM_BUFFER_SIZE. What is the result?

Best regards,
Dejan

[Shuhao Dong]

Hi,

We are using the ZDSD32 (this one here). It is basically a SD card without being able to plug in or out. 

Below is our current SPI configuration on the SPI4 bus in device tree

&spi4 {
    compatible = "nordic,nrf-spim";
    status = "okay";
    pinctrl-0 = <&spi4_default>;
    pinctrl-1 = <&spi4_sleep>;
    pinctrl-names = "default", "sleep";
    cs-gpios = <&gpio0 11 GPIO_ACTIVE_LOW>;

    sdhc0: sdhc@0 {
        compatible = "zephyr,sdhc-spi-slot";
        reg = <0>;
        status = "okay";
        mmc {
            compatible = "zephyr,sdmmc-disk";
            status = "okay";
            disk-name = "SD"; 
        };
        spi-max-frequency = <50000000>;
    };
};

and the pin control 

	spi4_default: spi4_default {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 8)>,
				<NRF_PSEL(SPIM_MOSI, 0, 9)>,
				<NRF_PSEL(SPIM_MISO, 0, 10)>;
			nordic,drive-mode = <NRF_DRIVE_H0H1>;
		};
	};

	spi4_sleep: spi4_sleep {
		group1 {
			psels = <NRF_PSEL(SPIM_SCK, 0, 8)>,
				<NRF_PSEL(SPIM_MOSI, 0, 9)>,
				<NRF_PSEL(SPIM_MISO, 0, 10)>;
			low-power-enable;
		};
	};

 

We will try to increase the buffer size as you recommended tmr to test the result.

Best

Shuhao

[Shuhao Dong]

Hello,

I have tried to increase the buffer size to 128 or 1024. I can confirm this has limited help on increasing transfer speed. Specifically, when copy 10.5 MB file, the time is decreased from previous 131 seconds to now 125 seconds (buffer size = 1024). There is an increase here but not a game changer. Can you suggest other posibilities to debug this issue?

[dejans]

Hi,

Can you share your complete project configuration?

Best regards,
Dejan

[Shuhao Dong]

Hi, 

Please find the complete one here

# Enable GPIO
CONFIG_GPIO=y
# Enable I2C
CONFIG_I2C=y
# Enable SPI
CONFIG_SPI=y

# Enable log and use it via Jlink RTT rather than CDC ACM 
CONFIG_LOG=y
CONFIG_USE_SEGGER_RTT=y
CONFIG_LOG_BACKEND_RTT=y    
CONFIG_LOG_BACKEND_UART=n
CONFIG_RTT_CONSOLE=n    
CONFIG_STDOUT_CONSOLE=n 
CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096  
CONFIG_LOG_BUFFER_SIZE=8192
CONFIG_UART_CONSOLE=n
CONFIG_CONSOLE=n

# Enable Bluetooth LE
CONFIG_BT=y
CONFIG_BT_PERIPHERAL=y
CONFIG_BT_DEVICE_NAME="BORUS"
CONFIG_BT_BROADCASTER=y
CONFIG_BT_OBSERVER=y
CONFIG_BT_FILTER_ACCEPT_LIST=y
# Extended BLE 
CONFIG_BT_EXT_ADV=y
CONFIG_BT_EXT_ADV_MAX_ADV_SET=2

# Enale floating point unit for float point calculation 
CONFIG_FPU=y
CONFIG_CBPRINTF_FP_SUPPORT=y

# Enable debugging 
CONFIG_DEBUG_THREAD_INFO=y
CONFIG_DEBUG_OPTIMIZATIONS=y

# Enable multithread
CONFIG_MULTITHREADING=y

# Enable battery voltage monitoring
CONFIG_SENSOR=y
CONFIG_PWM=n
CONFIG_ADC=y
CONFIG_VOLTAGE_DIVIDER=y
CONFIG_NRFX_SAADC=y

# Configure USB device
CONFIG_USB_DEVICE_STACK=y
CONFIG_USB_DEVICE_PRODUCT="BORUS"
CONFIG_USB_DEVICE_PID=0x0001
CONFIG_USB_DEVICE_VID=0x0001
CONFIG_USB_DRIVER_LOG_LEVEL_ERR=y
CONFIG_USB_DEVICE_LOG_LEVEL_ERR=y
CONFIG_SERIAL=n
CONFIG_USB_CDC_ACM=n
CONFIG_UART_INTERRUPT_DRIVEN=n
CONFIG_UART_LINE_CTRL=n
CONFIG_BOARD_SERIAL_BACKEND_CDC_ACM=n
CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n

# Configure USB device to appear as DFU class
# Configure DFU autoupdate and reset
CONFIG_USB_DFU_CLASS=y
CONFIG_USB_REQUEST_BUFFER_SIZE=128
CONFIG_USB_DFU_ENABLE_UPLOAD=y
CONFIG_USB_DFU_PERMANENT_DOWNLOAD=y
CONFIG_USB_DFU_REBOOT=y
CONFIG_IMG_MANAGER=y
CONFIG_STREAM_FLASH=y
CONFIG_BOOTLOADER_MCUBOOT=y

# Configure file system 
CONFIG_FLASH_MAP=y
CONFIG_FLASH=y
CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_LITTLEFS=n
CONFIG_FAT_FILESYSTEM_ELM=y
CONFIG_FS_FATFS_LFN=y
CONFIG_FS_FATFS_EXFAT=y
CONFIG_FS_LOG_LEVEL_INF=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_MPU_ALLOW_FLASH_WRITE=y
CONFIG_NORDIC_QSPI_NOR=y
CONFIG_NORDIC_QSPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096

# Configure SPI RAM buffer size
CONFIG_SPI_NRFX_RAM_BUFFER_SIZE=128

# Configure mass storage
CONFIG_USB_MASS_STORAGE=y
CONFIG_DISK_ACCESS=y
CONFIG_USB_MASS_STORAGE_LOG_LEVEL_ERR=y
CONFIG_DISK_LOG_LEVEL_DBG=y
CONFIG_DISK_DRIVERS=y
CONFIG_DISK_DRIVER_SDMMC=y
CONFIG_DISK_DRIVER_FLASH=y
CONFIG_MASS_STORAGE_DISK_NAME="SD"

# Configure BLE encryption
CONFIG_NRF_SECURITY=y
CONFIG_MBEDTLS_PSA_CRYPTO_C=y
CONFIG_PSA_CRYPTO_DRIVER_CC3XX=y
CONFIG_PSA_CRYPTO_DRIVER_OBERON=n
CONFIG_PSA_WANT_KEY_TYPE_AES=y
CONFIG_PSA_WANT_ALG_CTR=y
CONFIG_HEAP_MEM_POOL_SIZE=4096
CONFIG_MBEDTLS_ENABLE_HEAP=y
CONFIG_MBEDTLS_HEAP_SIZE=8192
CONFIG_TEST_RANDOM_GENERATOR=y

# Configure Settings subsystem
CONFIG_SETTINGS=y
CONFIG_SETTINGS_RUNTIME=y
CONFIG_NVS=y
CONFIG_SETTINGS_NVS=y
CONFIG_MPU_ALLOW_FLASH_WRITE=y

# Configure Watchdog
CONFIG_WATCHDOG=y
CONFIG_WDT_DISABLE_AT_BOOT=n

# Enable State Machine Framework
CONFIG_SMF=y

# Enable DSP
CONFIG_CMSIS_DSP=y
CONFIG_CMSIS_DSP_FILTERING=y
CONFIG_CMSIS_DSP_TRANSFORM=y
CONFIG_CMSIS_DSP_STATISTICS=y
CONFIG_CMSIS_DSP_FASTMATH=y
CONFIG_REQUIRES_FULL_LIBC=y
CONFIG_RING_BUFFER=y

# Power management
CONFIG_PM_DEVICE=y
CONFIG_RAM_POWER_DOWN_LIBRARY=y
CONFIG_POWEROFF=y

CONFIG_BMI270=y
CONFIG_BMI270_TRIGGER_GLOBAL_THREAD=y
CONFIG_BMP388=y
CONFIG_BMP388_TRIGGER_GLOBAL_THREAD=y
CONFIG_BMP388_ODR_RUNTIME=y
CONFIG_BMP388_OSR_RUNTIME=y 

# ------------------- Edge ML -------------------
CONFIG_CPP=y                
CONFIG_STD_CPP11=y
CONFIG_FP16=n
CONFIG_EDGE_IMPULSE=y
CONFIG_EDGE_IMPULSE_URI="/Users/gw23523/Downloads/test-cpp-mcu-v3.zip"
CONFIG_EI_WRAPPER=y

# ------------------- Turn below ON for Optimisation -------------------
# Stack sizes (This needs to be optimised using the thread analyzer below)
# CONFIG_MAIN_STACK_SIZE=1024
# CONFIG_ISR_STACK_SIZE=1536
# CONFIG_IDLE_STACK_SIZE=256
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048

# Thread analyser for debug purposes
# CONFIG_THREAD_ANALYZER=y
# CONFIG_THREAD_ANALYZER_USE_LOG=y
# CONFIG_THREAD_ANALYZER_AUTO=y
# CONFIG_THREAD_ANALYZER_AUTO_INTERVAL=10
# CONFIG_THREAD_NAME=y
# ----------------------------------------------------------------------