README ====== This README discusses issues unique to NuttX configurations for the STMicro STM32F746G-DISCO development board featuring the STM32F746NGH6 MCU. The STM32F746NGH6 is a 216MHz Cortex-M7 operation with 1024Kb Flash memory and 300Kb SRAM. The board features: - On-board ST-LINK/V2 for programming and debugging, - Mbed-enabled (mbed.org) - 4.3-inch 480x272 color LCD-TFT with capacitive touch screen - Camera connector - SAI audio codec - Audio line in and line out jack - Stereo speaker outputs - Two ST MEMS microphones - SPDIF RCA input connector - Two pushbuttons (user and reset) - 128-Mbit Quad-SPI Flash memory - 128-Mbit SDRAM (64 Mbits accessible) - Connector for microSD card - RF-EEPROM daughterboard connector - USB OTG HS with Micro-AB connectors - USB OTG FS with Micro-AB connectors - Ethernet connector compliant with IEEE-802.3-2002 Refer to the http://www.st.com website for further information about this board (search keyword: stm32f746g-disco) Contents ======== - Development Environment - LEDs and Buttons - Serial Console - FPU - STM32F746G-DISCO-specific Configuration Options - Configurations Development Environment ======================= The Development environments for the STM32F746G-DISCO board are identical to the environments for other STM32F boards. For full details on the environment options and setup, see the README.txt file in the config/stm32f746g-disco directory. LEDs and Buttons ================ LEDs ---- The STM32F746G-DISCO board has numerous LEDs but only one, LD1 located near the reset button, that can be controlled by software (LD2 is a power indicator, LD3-6 indicate USB status, LD7 is controlled by the ST-Link). LD1 is controlled by PI1 which is also the SPI2_SCK at the Arduino interface. One end of LD1 is grounded so a high output on PI1 will illuminate the LED. This LED is not used by the board port unless CONFIG_ARCH_LEDS is defined. In that case, the usage by the board port is defined in include/board.h and src/stm32_leds.c. The LEDs are used to encode OS-related events as follows: SYMBOL Meaning LD1 ------------------- ----------------------- ------ LED_STARTED NuttX has been started OFF LED_HEAPALLOCATE Heap has been allocated OFF LED_IRQSENABLED Interrupts enabled OFF LED_STACKCREATED Idle stack created ON LED_INIRQ In an interrupt N/C LED_SIGNAL In a signal handler N/C LED_ASSERTION An assertion failed N/C LED_PANIC The system has crashed FLASH Thus is LD1 is statically on, NuttX has successfully booted and is, apparently, running normally. If LD1 is flashing at approximately 2Hz, then a fatal error has been detected and the system has halted. Buttons ------- Pushbutton B1, labelled "User", is connected to GPIO PI11. A high value will be sensed when the button is depressed. Serial Console ============== These configurations assume that you are using a standard Arduio RS-232 shield with the serial interface with RX on pin D0 and TX on pin D1: -------- --------------- STM32F7 ARDUIONO FUNCTION GPIO -- ----- --------- ----- DO RX USART6_RX PC7 D1 TX USART6_TX PC6 -- ----- --------- ----- FPU === FPU Configuration Options ------------------------- There are two version of the FPU support built into the STM32 port. 1. Lazy Floating Point Register Save. This is an implementation that saves and restores FPU registers only on context switches. This means: (1) floating point registers are not stored on each context switch and, hence, possibly better interrupt performance. But, (2) since floating point registers are not saved, you cannot use floating point operations within interrupt handlers. This logic can be enabled by simply adding the following to your .config file: CONFIG_ARCH_FPU=y CONFIG_ARMV7M_CMNVECTOR=y CONFIG_ARMV7M_LAZYFPU=y 2. Non-Lazy Floating Point Register Save Mike Smith has contributed an extensive re-write of the ARMv7-M exception handling logic. This includes verified support for the FPU. These changes have not yet been incorporated into the mainline and are still considered experimental. These FPU logic can be enabled with: CONFIG_ARCH_FPU=y CONFIG_ARMV7M_CMNVECTOR=y You will probably also changes to the ld.script in if this option is selected. This should work: -ENTRY(_stext) +ENTRY(__start) /* Treat __start as the anchor for dead code stripping */ +EXTERN(_vectors) /* Force the vectors to be included in the output */ STM32F746G-DISCO-specific Configuration Options =============================================== CONFIG_ARCH - Identifies the arch/ subdirectory. This should be set to: CONFIG_ARCH=arm CONFIG_ARCH_family - For use in C code: CONFIG_ARCH_ARM=y CONFIG_ARCH_architecture - For use in C code: CONFIG_ARCH_CORTEXM4=y CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory CONFIG_ARCH_CHIP=stm32 CONFIG_ARCH_CHIP_name - For use in C code to identify the exact chip: CONFIG_ARCH_CHIP_STM32F746=y CONFIG_ARCH_BOARD_STM32_CUSTOM_CLOCKCONFIG - Enables special STM32 clock configuration features. CONFIG_ARCH_BOARD_STM32_CUSTOM_CLOCKCONFIG=n CONFIG_ARCH_BOARD - Identifies the configs subdirectory and hence, the board that supports the particular chip or SoC. CONFIG_ARCH_BOARD=STM32F746G-DISCO (for the STM32F746G-DISCO development board) CONFIG_ARCH_BOARD_name - For use in C code CONFIG_ARCH_BOARD_STM32F746G_DISCO=y CONFIG_ARCH_LOOPSPERMSEC - Must be calibrated for correct operation of delay loops CONFIG_ENDIAN_BIG - define if big endian (default is little endian) CONFIG_RAM_SIZE - Describes the installed DRAM (SRAM in this case): CONFIG_RAM_SIZE=0x00010000 (64Kb) CONFIG_RAM_START - The start address of installed DRAM CONFIG_RAM_START=0x20000000 In order to use FSMC SRAM, the following additional things need to be present in the NuttX configuration file: CONFIG_STM32F7_FSMC_SRAM - Indicates that SRAM is available via the FSMC (as opposed to an LCD or FLASH). CONFIG_HEAP2_BASE - The base address of the SRAM in the FSMC address space (hex) CONFIG_HEAP2_SIZE - The size of the SRAM in the FSMC address space (decimal) CONFIG_ARCH_FPU - The STM32F746G-DISCO supports a floating point unit (FPU) CONFIG_ARCH_FPU=y CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to boards that have LEDs CONFIG_ARCH_INTERRUPTSTACK - This architecture supports an interrupt stack. If defined, this symbol is the size of the interrupt stack in bytes. If not defined, the user task stacks will be used during interrupt handling. CONFIG_ARCH_STACKDUMP - Do stack dumps after assertions CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to board architecture. CONFIG_ARCH_CALIBRATION - Enables some build in instrumentation that cause a 100 second delay during boot-up. This 100 second delay serves no purpose other than it allows you to calibratre CONFIG_ARCH_LOOPSPERMSEC. You simply use a stop watch to measure the 100 second delay then adjust CONFIG_ARCH_LOOPSPERMSEC until the delay actually is 100 seconds. Individual subsystems can be enabled: APB1 ---- CONFIG_STM32F7_TIM2 TIM2 CONFIG_STM32F7_TIM3 TIM3 CONFIG_STM32F7_TIM4 TIM4 CONFIG_STM32F7_TIM5 TIM5 CONFIG_STM32F7_TIM6 TIM6 CONFIG_STM32F7_TIM7 TIM7 CONFIG_STM32F7_TIM12 TIM12 CONFIG_STM32F7_TIM13 TIM13 CONFIG_STM32F7_TIM14 TIM14 CONFIG_STM32F7_LPTIM1 LPTIM1 CONFIG_STM32F7_RTC RTC CONFIG_STM32F7_BKP BKP Registers CONFIG_STM32F7_WWDG WWDG CONFIG_STM32F7_IWDG IWDG CONFIG_STM32F7_SPI2 SPI2 CONFIG_STM32F7_I2S2 I2S2 CONFIG_STM32F7_SPI3 SPI3 CONFIG_STM32F7_I2S3 I2S3 CONFIG_STM32F7_SPDIFRX SPDIFRX CONFIG_STM32F7_USART2 USART2 CONFIG_STM32F7_USART3 USART3 CONFIG_STM32F7_UART4 UART4 CONFIG_STM32F7_UART5 UART5 CONFIG_STM32F7_I2C1 I2C1 CONFIG_STM32F7_I2C2 I2C2 CONFIG_STM32F7_I2C3 I2C3 CONFIG_STM32F7_I2C4 I2C4 CONFIG_STM32F7_CAN1 CAN1 CONFIG_STM32F7_CAN2 CAN2 CONFIG_STM32F7_HDMICEC HDMI-CEC CONFIG_STM32F7_PWR PWR CONFIG_STM32F7_DAC DAC CONFIG_STM32F7_UART7 UART7 CONFIG_STM32F7_UART8 UART8 APB2 ---- CONFIG_STM32F7_TIM1 TIM1 CONFIG_STM32F7_TIM8 TIM8 CONFIG_STM32F7_USART1 USART1 CONFIG_STM32F7_USART6 USART6 CONFIG_STM32F7_ADC ADC1 - ADC2 - ADC3 CONFIG_STM32F7_SDMMC1 SDMMC1 CONFIG_STM32F7_SPI1 SPI1 CONFIG_STM32F7_SPI4 SPI4 CONFIG_STM32F7_SYSCFG SYSCFG CONFIG_STM32F7_EXTI EXTI CONFIG_STM32F7_TIM9 TIM9 CONFIG_STM32F7_TIM10 TIM10 CONFIG_STM32F7_TIM11 TIM11 CONFIG_STM32F7_SPI5 SPI5 CONFIG_STM32F7_SPI6 SPI6 CONFIG_STM32F7_SAI1 SAI1 CONFIG_STM32F7_SAI2 SAI2 CONFIG_STM32F7_LTDC LCD-TFT AHB1 ---- CONFIG_STM32F7_CRC CRC CONFIG_STM32F7_BKPSRAM BKPSRAM CONFIG_STM32F7_DMA1 DMA1 CONFIG_STM32F7_DMA2 DMA2 CONFIG_STM32F7_ETHMAC Ethernet MAC CONFIG_STM32F7_DMA2D Chrom-ART (DMA2D) CONFIG_STM32F7_USBOTGHS USB OTG HS AHB2 ---- CONFIG_STM32F7_USBOTGFS USB OTG FS CONFIG_STM32F7_DCMI DCMI CONFIG_STM32F7_CRYP CRYP CONFIG_STM32F7_HASH HASH CONFIG_STM32F7_RNG RNG AHB3 ---- CONFIG_STM32F7_FSMC FSMC control registers CONFIG_STM32F7_QUADSPI QuadSPI Control Timer devices may be used for different purposes. One special purpose is to generate modulated outputs for such things as motor control. If CONFIG_STM32F7_TIMn is defined (as above) then the following may also be defined to indicate that the timer is intended to be used for pulsed output modulation, ADC conversion, or DAC conversion. Note that ADC/DAC require two definition: Not only do you have to assign the timer (n) for used by the ADC or DAC, but then you also have to configure which ADC or DAC (m) it is assigned to. CONFIG_STM32F7_TIMn_PWM Reserve timer n for use by PWM, n=1,..,14 CONFIG_STM32F7_TIMn_ADC Reserve timer n for use by ADC, n=1,..,14 CONFIG_STM32F7_TIMn_ADCm Reserve timer n to trigger ADCm, n=1,..,14, m=1,..,3 CONFIG_STM32F7_TIMn_DAC Reserve timer n for use by DAC, n=1,..,14 CONFIG_STM32F7_TIMn_DACm Reserve timer n to trigger DACm, n=1,..,14, m=1,..,2 For each timer that is enabled for PWM usage, we need the following additional configuration settings: CONFIG_STM32F7_TIMx_CHANNEL - Specifies the timer output channel {1,..,4} NOTE: The STM32 timers are each capable of generating different signals on each of the four channels with different duty cycles. That capability is not supported by this driver: Only one output channel per timer. JTAG Enable settings (by default only SW-DP is enabled): CONFIG_STM32F7_JTAG_FULL_ENABLE - Enables full SWJ (JTAG-DP + SW-DP) CONFIG_STM32F7_JTAG_NOJNTRST_ENABLE - Enables full SWJ (JTAG-DP + SW-DP) but without JNTRST. CONFIG_STM32F7_JTAG_SW_ENABLE - Set JTAG-DP disabled and SW-DP enabled STM32F746G-DISCO specific device driver settings CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the USARTn (n=1,2,3) or UART m (m=4,5) for the console and ttys0 (default is the USART1). CONFIG_U[S]ARTn_RXBUFSIZE - Characters are buffered as received. This specific the size of the receive buffer CONFIG_U[S]ARTn_TXBUFSIZE - Characters are buffered before being sent. This specific the size of the transmit buffer CONFIG_U[S]ARTn_BAUD - The configure BAUD of the UART. Must be CONFIG_U[S]ARTn_BITS - The number of bits. Must be either 7 or 8. CONFIG_U[S]ARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity CONFIG_U[S]ARTn_2STOP - Two stop bits STM32F746G-DISCO CAN Configuration CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32F7_CAN1 or CONFIG_STM32F7_CAN2 must also be defined) CONFIG_CAN_EXTID - Enables support for the 29-bit extended ID. Default Standard 11-bit IDs. CONFIG_CAN_FIFOSIZE - The size of the circular buffer of CAN messages. Default: 8 CONFIG_CAN_NPENDINGRTR - The size of the list of pending RTR requests. Default: 4 CONFIG_CAN_LOOPBACK - A CAN driver may or may not support a loopback mode for testing. The STM32 CAN driver does support loopback mode. CONFIG_CAN1_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32F7_CAN1 is defined. CONFIG_CAN2_BAUD - CAN1 BAUD rate. Required if CONFIG_STM32F7_CAN2 is defined. CONFIG_CAN_TSEG1 - The number of CAN time quanta in segment 1. Default: 6 CONFIG_CAN_TSEG2 - the number of CAN time quanta in segment 2. Default: 7 CONFIG_CAN_REGDEBUG - If CONFIG_DEBUG is set, this will generate an dump of all CAN registers. STM32F746G-DISCO SPI Configuration CONFIG_STM32F7_SPI_INTERRUPTS - Select to enable interrupt driven SPI support. Non-interrupt-driven, poll-waiting is recommended if the interrupt rate would be to high in the interrupt driven case. CONFIG_STM32F7_SPI_DMA - Use DMA to improve SPI transfer performance. Cannot be used with CONFIG_STM32F7_SPI_INTERRUPT. STM32F746G-DISCO DMA Configuration CONFIG_SDIO_DMA - Support DMA data transfers. Requires CONFIG_STM32F7_SDIO and CONFIG_STM32F7_DMA2. CONFIG_SDIO_PRI - Select SDIO interrupt prority. Default: 128 CONFIG_SDIO_DMAPRIO - Select SDIO DMA interrupt priority. Default: Medium CONFIG_SDIO_WIDTH_D1_ONLY - Select 1-bit transfer mode. Default: 4-bit transfer mode. STM32 USB OTG FS Host Driver Support Pre-requisites CONFIG_USBDEV - Enable USB device support CONFIG_USBHOST - Enable USB host support CONFIG_STM32F7_OTGFS - Enable the STM32 USB OTG FS block CONFIG_STM32F7_SYSCFG - Needed CONFIG_SCHED_WORKQUEUE - Worker thread support is required Options: CONFIG_STM32F7_OTGFS_RXFIFO_SIZE - Size of the RX FIFO in 32-bit words. Default 128 (512 bytes) CONFIG_STM32F7_OTGFS_NPTXFIFO_SIZE - Size of the non-periodic Tx FIFO in 32-bit words. Default 96 (384 bytes) CONFIG_STM32F7_OTGFS_PTXFIFO_SIZE - Size of the periodic Tx FIFO in 32-bit words. Default 96 (384 bytes) CONFIG_STM32F7_OTGFS_DESCSIZE - Maximum size of a descriptor. Default: 128 CONFIG_STM32F7_OTGFS_SOFINTR - Enable SOF interrupts. Why would you ever want to do that? CONFIG_STM32F7_USBHOST_REGDEBUG - Enable very low-level register access debug. Depends on CONFIG_DEBUG. CONFIG_STM32F7_USBHOST_PKTDUMP - Dump all incoming and outgoing USB packets. Depends on CONFIG_DEBUG. Configurations ============== Each STM32F746G-DISCO configuration is maintained in a sub-directory and can be selected as follow: cd tools ./configure.sh stm32f746g-disco/ cd - . ./setenv.sh If this is a Windows native build, then configure.bat should be used instead of configure.sh: configure.bat STM32F746G-DISCO\ Where is one of the following: nsh: --- Configures the NuttShell (nsh) located at apps/examples/nsh. The Configuration enables the serial interfaces on UART2. Support for builtin applications is enabled, but in the base configuration no builtin applications are selected (see NOTES below). NOTES: 1. This configuration uses the mconf-based configuration tool. To change this configuration using that tool, you should: a. Build and install the kconfig-mconf tool. See nuttx/README.txt see additional README.txt files in the NuttX tools repository. b. Execute 'make menuconfig' in nuttx/ in order to start the reconfiguration process. 2. By default, this configuration uses the CodeSourcery toolchain for Windows and builds under Cygwin (or probably MSYS). That can easily be reconfigured, of course. CONFIG_HOST_WINDOWS=y : Builds under Windows CONFIG_WINDOWS_CYGWIN=y : Using Cygwin CONFIG_ARMV7M_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery for Windows 3. This example supports the PWM test (apps/examples/pwm) but this must be manually enabled by selecting: CONFIG_PWM=y : Enable the generic PWM infrastructure CONFIG_STM32F7_TIM4=y : Enable TIM4 CONFIG_STM32F7_TIM4_PWM=y : Use TIM4 to generate PWM output See also apps/examples/README.txt Special PWM-only debug options: CONFIG_DEBUG_PWM 5. This example supports the Quadrature Encode test (apps/examples/qencoder) but this must be manually enabled by selecting: CONFIG_EXAMPLES_QENCODER=y : Enable the apps/examples/qencoder CONFIG_SENSORS=y : Enable support for sensors CONFIG_QENCODER=y : Enable the generic Quadrature Encoder infrastructure CONFIG_STM32F7_TIM8=y : Enable TIM8 CONFIG_STM32F7_TIM2=n : (Or optionally TIM2) CONFIG_STM32F7_TIM8_QE=y : Use TIM8 as the quadrature encoder CONFIG_STM32F7_TIM2_QE=y : (Or optionally TIM2) See also apps/examples/README.txt. Special debug options: CONFIG_DEBUG_SENSORS 6. This example supports the watchdog timer test (apps/examples/watchdog) but this must be manually enabled by selecting: CONFIG_EXAMPLES_WATCHDOG=y : Enable the apps/examples/watchdog CONFIG_WATCHDOG=y : Enables watchdog timer driver support CONFIG_STM32F7_WWDG=y : Enables the WWDG timer facility, OR CONFIG_STM32F7_IWDG=y : Enables the IWDG timer facility (but not both) The WWDG watchdog is driven off the (fast) 42MHz PCLK1 and, as result, has a maximum timeout value of 49 milliseconds. for WWDG watchdog, you should also add the fillowing to the configuration file: CONFIG_EXAMPLES_WATCHDOG_PINGDELAY=20 CONFIG_EXAMPLES_WATCHDOG_TIMEOUT=49 The IWDG timer has a range of about 35 seconds and should not be an issue. 7. USB Support (CDC/ACM device) CONFIG_STM32F7_OTGFS=y : STM32 OTG FS support CONFIG_USBDEV=y : USB device support must be enabled CONFIG_CDCACM=y : The CDC/ACM driver must be built CONFIG_NSH_BUILTIN_APPS=y : NSH built-in application support must be enabled CONFIG_NSH_ARCHINIT=y : To perform USB initialization 8. Using the USB console. The STM32F746G-DISCO NSH configuration can be set up to use a USB CDC/ACM (or PL2303) USB console. The normal way that you would configure the the USB console would be to change the .config file like this: CONFIG_STM32F7_OTGFS=y : STM32 OTG FS support CONFIG_USART2_SERIAL_CONSOLE=n : Disable the USART2 console CONFIG_DEV_CONSOLE=n : Inhibit use of /dev/console by other logic CONFIG_USBDEV=y : USB device support must be enabled CONFIG_CDCACM=y : The CDC/ACM driver must be built CONFIG_CDCACM_CONSOLE=y : Enable the CDC/ACM USB console. NOTE: When you first start the USB console, you have hit ENTER a few times before NSH starts. The logic does this to prevent sending USB data before there is anything on the host side listening for USB serial input. 9. Here is an alternative USB console configuration. The following configuration will also create a NSH USB console but this version will use /dev/console. Instead, it will use the normal /dev/ttyACM0 USB serial device for the console: CONFIG_STM32F7_OTGFS=y : STM32 OTG FS support CONFIG_USART2_SERIAL_CONSOLE=y : Keep the USART2 console CONFIG_DEV_CONSOLE=y : /dev/console exists (but NSH won't use it) CONFIG_USBDEV=y : USB device support must be enabled CONFIG_CDCACM=y : The CDC/ACM driver must be built CONFIG_CDCACM_CONSOLE=n : Don't use the CDC/ACM USB console. CONFIG_NSH_USBCONSOLE=y : Instead use some other USB device for the console The particular USB device that is used is: CONFIG_NSH_USBCONDEV="/dev/ttyACM0" The advantage of this configuration is only that it is easier to bet working. This alternative does has some side effects: - When any other device other than /dev/console is used for a user interface, linefeeds (\n) will not be expanded to carriage return / linefeeds (\r\n). You will need to set your terminal program to account for this. - /dev/console still exists and still refers to the serial port. So you can still use certain kinds of debug output (see include/debug.h, all of the interfaces based on lowsyslog will work in this configuration). - But don't enable USB debug output! Since USB is console is used for USB debug output and you are using a USB console, there will be infinite loops and deadlocks: Debug output generates USB debug output which generatates USB debug output, etc. If you want USB debug output, you should consider enabling USB trace (CONFIG_USBDEV_TRACE) and perhaps the USB monitor (CONFIG_SYSTEM_USBMONITOR). See the usbnsh configuration below for more information on configuring USB trace output and the USB monitor. 10. USB OTG FS Host Support. The following changes will enable support for a USB host on the STM32F746G-DISCO, including support for a mass storage class driver: Device Drivers -> CONFIG_USBDEV=n : Make sure tht USB device support is disabled CONFIG_USBHOST=y : Enable USB host support CONFIG_USBHOST_ISOC_DISABLE=y Device Drivers -> USB Host Driver Support CONFIG_USBHOST_MSC=y : Enable the mass storage class System Type -> STM32 Peripheral Support CONFIG_STM32F7_OTGHS=y : Enable the STM32 USB OTG FH block (FS mode) CONFIG_STM32F7_SYSCFG=y : Needed for all USB OTF HS support RTOS Features -> Work Queue Support CONFIG_SCHED_WORKQUEUE=y : High priority worker thread support is required CONFIG_SCHED_HPWORK=y : for the mass storage class driver. File Systems -> CONFIG_FS_FAT=y : Needed by the USB host mass storage class. Board Selection -> CONFIG_LIB_BOARDCTL=y : Needed for CONFIG_NSH_ARCHINIT Application Configuration -> NSH Library CONFIG_NSH_ARCHINIT=y : Architecture specific USB initialization : is needed for NSH With those changes, you can use NSH with a FLASH pen driver as shown belong. Here NSH is started with nothing in the USB host slot: NuttShell (NSH) NuttX-x.yy nsh> ls /dev /dev: console null ttyS0 After inserting the FLASH drive, the /dev/sda appears and can be mounted like this: nsh> ls /dev /dev: console null sda ttyS0 nsh> mount -t vfat /dev/sda /mnt/stuff nsh> ls /mnt/stuff /mnt/stuff: -rw-rw-rw- 16236 filea.c And files on the FLASH can be manipulated to standard interfaces: nsh> echo "This is a test" >/mnt/stuff/atest.txt nsh> ls /mnt/stuff /mnt/stuff: -rw-rw-rw- 16236 filea.c -rw-rw-rw- 16 atest.txt nsh> cat /mnt/stuff/atest.txt This is a test nsh> cp /mnt/stuff/filea.c fileb.c nsh> ls /mnt/stuff /mnt/stuff: -rw-rw-rw- 16236 filea.c -rw-rw-rw- 16 atest.txt -rw-rw-rw- 16236 fileb.c To prevent data loss, don't forget to un-mount the FLASH drive before removing it: nsh> umount /mnt/stuff 11. I used this configuration to test the USB hub class. I did this testing with the following changes to the configuration (in addition to those listed above for base USB host/mass storage class support): Drivers -> USB Host Driver Support CONFIG_USBHOST_HUB=y : Enable the hub class CONFIG_USBHOST_ASYNCH=y : Asynchonous I/O supported needed for hubs Board Selection -> CONFIG_STM32F746GDISCO_USBHOST_STACKSIZE=2048 (bigger than it needs to be) RTOS Features -> Work Queue Support CONFIG_SCHED_LPWORK=y : Low priority queue support is needed CONFIG_SCHED_LPNTHREADS=1 CONFIG_SCHED_LPWORKSTACKSIZE=1024 NOTES: 1. It is necessary to perform work on the low-priority work queue (vs. the high priority work queue) because deferred hub-related work requires some delays and waiting that is not appropriate on the high priority work queue. 2. Stack usage make increase when USB hub support is enabled because the nesting depth of certain USB host class logic can increase.