px4-firmware/nuttx/configs/hymini-stm32v

README
======

This README discusses issues unique to NuttX configurations for the
HY-MiniSTM32V development board.

Contents
========

  - Development Environment
  - GNU Toolchain Options
  - IDEs
  - NuttX buildroot Toolchain
  - DFU
  - LEDs
  - RTC
  - HY-Mini specific Configuration Options
  - Configurations

Development Environment
=======================

  Either Linux or Cygwin on Windows can be used for the development environment.
  The source has been built only using the GNU toolchain (see below).  Other
  toolchains will likely cause problems. Testing was performed using the Cygwin
  environment because the Raisonance R-Link emulatator and some RIDE7 development tools
  were used and those tools works only under Windows.

GNU Toolchain Options
=====================

  The NuttX make system has been modified to support the following different
  toolchain options.

  1. The CodeSourcery GNU toolchain,
  2. The devkitARM GNU toolchain,
  3. Raisonance GNU toolchain, or
  4. The NuttX buildroot Toolchain (see below).

  All testing has been conducted using the NuttX buildroot toolchain.  However,
  the make system is setup to default to use the devkitARM toolchain.  To use
  the CodeSourcery, devkitARM or Raisonance GNU toolchain, you simply need to
  add one of the following configuration options to your .config (or defconfig)
  file:

    CONFIG_STM32_CODESOURCERYW=y  : CodeSourcery under Windows
    CONFIG_STM32_CODESOURCERYL=y  : CodeSourcery under Linux
    CONFIG_STM32_DEVKITARM=y      : devkitARM under Windows
    CONFIG_STM32_RAISONANCE=y     : Raisonance RIDE7 under Windows
    CONFIG_STM32_BUILDROOT=y	  : NuttX buildroot under Linux or Cygwin (default)

  If you are not using CONFIG_STM32_BUILDROOT, then you may also have to modify
  the PATH in the setenv.h file if your make cannot find the tools.

  NOTE: the CodeSourcery (for Windows), devkitARM, and Raisonance toolchains are
  Windows native toolchains.  The CodeSourcey (for Linux) and NuttX buildroot
  toolchains are Cygwin and/or Linux native toolchains. There are several limitations
  to using a Windows based toolchain in a Cygwin environment.  The three biggest are:

  1. The Windows toolchain cannot follow Cygwin paths.  Path conversions are
     performed automatically in the Cygwin makefiles using the 'cygpath' utility
     but you might easily find some new path problems.  If so, check out 'cygpath -w'

  2. Windows toolchains cannot follow Cygwin symbolic links.  Many symbolic links
     are used in Nuttx (e.g., include/arch).  The make system works around these
     problems for the Windows tools by copying directories instead of linking them.
     But this can also cause some confusion for you:  For example, you may edit
     a file in a "linked" directory and find that your changes had no effect.
     That is because you are building the copy of the file in the "fake" symbolic
     directory.  If you use a Windows toolchain, you should get in the habit of
     making like this:

       make clean_context all

     An alias in your .bashrc file might make that less painful.

  3. Dependencies are not made when using Windows versions of the GCC.  This is
     because the dependencies are generated using Windows pathes which do not
     work with the Cygwin make.

     Support has been added for making dependencies with the windows-native toolchains.
     That support can be enabled by modifying your Make.defs file as follows:

    -  MKDEP                = $(TOPDIR)/tools/mknulldeps.sh
    +  MKDEP                = $(TOPDIR)/tools/mkdeps.sh --winpaths "$(TOPDIR)"

     If you have problems with the dependency build (for example, if you are not
     building on C:), then you may need to modify tools/mkdeps.sh

  NOTE 1: The CodeSourcery toolchain (2009q1) does not work with default optimization
  level of -Os (See Make.defs).  It will work with -O0, -O1, or -O2, but not with
  -Os.

  NOTE 2: The devkitARM toolchain includes a version of MSYS make.  Make sure that
  the paths to Cygwin's /bin and /usr/bin directories appear BEFORE the devkitARM
  path or will get the wrong version of make.

IDEs
====

  NuttX is built using command-line make.  It can be used with an IDE, but some
  effort will be required to create the project (There is a simple RIDE project
  in the RIDE subdirectory).
  
  Makefile Build
  --------------
  Under Eclipse, it is pretty easy to set up an "empty makefile project" and
  simply use the NuttX makefile to build the system.  That is almost for free
  under Linux.  Under Windows, you will need to set up the "Cygwin GCC" empty
  makefile project in order to work with Windows (Google for "Eclipse Cygwin" -
  there is a lot of help on the internet).

  Native Build
  ------------
  Here are a few tips before you start that effort:

  1) Select the toolchain that you will be using in your .config file
  2) Start the NuttX build at least one time from the Cygwin command line
     before trying to create your project.  This is necessary to create
     certain auto-generated files and directories that will be needed.
  3) Set up include pathes:  You will need include/, arch/arm/src/stm32,
     arch/arm/src/common, arch/arm/src/armv7-m, and sched/.
  4) All assembly files need to have the definition option -D __ASSEMBLY__
     on the command line.

  Startup files will probably cause you some headaches.  The NuttX startup file
  is arch/arm/src/stm32/stm32_vectors.S.  With RIDE, I have to build NuttX
  one time from the Cygwin command line in order to obtain the pre-built
  startup object needed by RIDE.

NuttX buildroot Toolchain
=========================

  A GNU GCC-based toolchain is assumed.  The files */setenv.sh should
  be modified to point to the correct path to the Cortex-M3 GCC toolchain (if
  different from the default in your PATH variable).

  If you have no Cortex-M3 toolchain, one can be downloaded from the NuttX
  SourceForge download site (https://sourceforge.net/project/showfiles.php?group_id=189573).
  This GNU toolchain builds and executes in the Linux or Cygwin environment.

  1. You must have already configured Nuttx in <some-dir>/nuttx.

     cd tools
     ./configure.sh hymini-stm32v/<sub-dir>

  2. Download the latest buildroot package into <some-dir>

  3. unpack the buildroot tarball.  The resulting directory may
     have versioning information on it like buildroot-x.y.z.  If so,
     rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot.

  4. cd <some-dir>/buildroot

  5. cp configs/cortexm3-defconfig-4.3.3 .config

  6. make oldconfig

  7. make

  8. Edit setenv.h, if necessary, so that the PATH variable includes
     the path to the newly built binaries.

  See the file configs/README.txt in the buildroot source tree.  That has more
  detailed PLUS some special instructions that you will need to follow if you are
  building a Cortex-M3 toolchain for Cygwin under Windows.

DFU
===

  The linker files in these projects can be configured to indicate that you
  will be loading code using STMicro built-in USB Device Firmware Upgrade (DFU)
  loader or via some JTAG emulator.  You can specify the DFU bootloader by
  adding the following line:

    CONFIG_STM32_DFU=y

  to your .config file. Most of the configurations in this directory are set
  up to use the DFU loader.

  If CONFIG_STM32_DFU is defined, the code will not be positioned at the beginning
  of FLASH (0x08000000) but will be offset to 0x08003000.  This offset is needed
  to make space for the DFU loader and 0x08003000 is where the DFU loader expects
  to find new applications at boot time.  If you need to change that origin for some
  other bootloader, you will need to edit the file(s) ld.script.dfu for each
  configuration.

  The DFU SE PC-based software is available from the STMicro website,
  http://www.st.com.  General usage instructions:
  
  1. Convert the NuttX Intel Hex file (nuttx.hex) into a special DFU
     file (nuttx.dfu)... see below for details.
  2. Connect the Hy-Mini STM32v board to your computer using a USB
     cable.
  3. Start the DFU loader on the Hy-Mini STM32v board.  You do this by
     resetting the board while holding the "Key" button.  Windows should
     recognize that the DFU loader has been installed.
  3. Run the DFU SE program to load nuttx.dfu into FLASH.

  What if the DFU loader is not in FLASH?  The loader code is available
  inside of the Demo dirctory of the USBLib ZIP file that can be downloaded
  from the STMicro Website.  You can build it using RIDE (or other toolchains);
  you will need a JTAG emulator to burn it into FLASH the first time.

  In order to use STMicro's built-in DFU loader, you will have to get
  the NuttX binary into a special format with a .dfu extension.  The
  DFU SE PC_based software installation includes a file "DFU File Manager"
  conversion program that a file in Intel Hex format to the special DFU
  format.  When you successfully build NuttX, you will find a file called
  nutt.hex in the top-level directory.  That is the file that you should
  provide to the DFU File Manager. You will end up with a file called
  nuttx.dfu that you can use with the STMicro DFU SE program.

LEDs
====

The HY-MiniSTM32 board provides only two controlable LEDs labeled LED1 and LED2.
Usage of these LEDs is defined in include/board.h and src/up_leds.c.
They are encoded as follows:

	SYMBOL				Meaning					LED1*	LED2	
	-------------------	-----------------------	-------	-------	
	LED_STARTED			NuttX has been started	OFF		OFF		
	LED_HEAPALLOCATE	Heap has been allocated	ON		OFF		
	LED_IRQSENABLED		Interrupts enabled		OFF		ON		
	LED_STACKCREATED	Idle stack created		ON		OFF		
	LED_INIRQ			In an interrupt**		OFF		N/C		
	LED_SIGNAL			In a signal handler***  N/C		ON		
	LED_ASSERTION		An assertion failed		ON		ON		
	LED_PANIC			The system has crashed	BLINK	BLINK		
    LED_IDLE            STM32 is is sleep mode  (Optional, not used)

  * If Nuttx starts correctly, normal state is to have LED1 on and LED2 off.
 ** LED1 is turned off during interrrupt.
*** LED2 is turned on during signal handler.

RTC
===

  The STM32 RTC may configured using the following settings.

    CONFIG_RTC - Enables general support for a hardware RTC. Specific
      architectures may require other specific settings.
    CONFIG_RTC_HIRES - The typical RTC keeps time to resolution of 1
      second, usually supporting a 32-bit time_t value.  In this case,
      the RTC is used to &quot;seed&quot; the normal NuttX timer and the
      NuttX timer provides for higher resoution time. If CONFIG_RTC_HIRES
      is enabled in the NuttX configuration, then the RTC provides higher
      resolution time and completely replaces the system timer for purpose of
      date and time.
      CONFIG_RTC_FREQUENCY - If CONFIG_RTC_HIRES is defined, then the
      frequency of the high resolution RTC must be provided.  If CONFIG_RTC_HIRES
      is not defined, CONFIG_RTC_FREQUENCY is assumed to be one.
    CONFIG_RTC_ALARM - Enable if the RTC hardware supports setting of an alarm. 
      A callback function will be executed when the alarm goes off

  In hi-res mode, the STM32 RTC operates only at 16384Hz.  Overflow interrupts
  are handled when the 32-bit RTC counter overflows every 3 days and 43 minutes.
  A BKP register is incremented on each overflow interrupt creating, effectively,
  a 48-bit RTC counter.

  In the lo-res mode, the RTC operates at 1Hz.  Overflow interrupts are not handled
  (because the next overflow is not expected until the year 2106.

   WARNING:  Overflow interrupts are lost whenever the STM32 is powered down.  The
   overflow interrupt may be lost even if the STM32 is powered down only momentarily.
   Therefore hi-res solution is only useful in systems where the power is always on.

HY-Mini 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_CORTEXM3=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_STM32F103VCT6

    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=hymini-stm32v (for the HY-Mini development board)

	CONFIG_ARCH_BOARD_name - For use in C code

	   CONFIG_ARCH_BOARD_HYMINI_STM32V=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_DRAM_SIZE - Describes the installed DRAM (SRAM in this case):

	   CONFIG_DRAM_SIZE=0x0000C000 (48Kb)

	CONFIG_DRAM_START - The start address of installed DRAM

	   CONFIG_DRAM_START=0x20000000

	CONFIG_DRAM_END - Last address+1 of installed RAM

	   CONFIG_DRAM_END=(CONFIG_DRAM_START+CONFIG_DRAM_SIZE)

	CONFIG_ARCH_IRQPRIO - The STM32F103V supports interrupt prioritization

	   CONFIG_ARCH_IRQPRIO=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:
	AHB
	---
	CONFIG_STM32_DMA1
	CONFIG_STM32_DMA2
	CONFIG_STM32_CRC
	CONFIG_STM32_FSMC
	CONFIG_STM32_SDIO

	APB1
	----
	CONFIG_STM32_TIM2
	CONFIG_STM32_TIM3    (required for PWM control of LCD backlight)
	CONFIG_STM32_TIM4
	CONFIG_STM32_TIM5
	CONFIG_STM32_TIM6
	CONFIG_STM32_TIM7
	CONFIG_STM32_IWDG
	CONFIG_STM32_WWDG
	CONFIG_STM32_IWDG
	CONFIG_STM32_SPI2
	CONFIG_STM32_SPI4
	CONFIG_STM32_USART2
	CONFIG_STM32_USART3
	CONFIG_STM32_UART4
	CONFIG_STM32_UART5
	CONFIG_STM32_I2C1
	CONFIG_STM32_I2C2
	CONFIG_STM32_USB
	CONFIG_STM32_CAN1
	CONFIG_STM32_BKP
	CONFIG_STM32_PWR
	CONFIG_STM32_DAC
	CONFIG_STM32_USB

	APB2
	----
	CONFIG_STM32_ADC1
	CONFIG_STM32_ADC2
	CONFIG_STM32_TIM1
	CONFIG_STM32_SPI1
	CONFIG_STM32_TIM8
	CONFIG_STM32_USART1
	CONFIG_STM32_ADC3

  Timer and I2C devices may need to the following to force power to be applied
  unconditionally at power up.  (Otherwise, the device is powered when it is
  initialized).

    CONFIG_STM32_FORCEPOWER

  The Timer3 alternate mapping is required for PWM control of LCD backlight
  
    CONFIG_STM32_TIM3_PARTIAL_REMAP=y
    
  Timer devices may be used for different purposes.  One special purpose is
  to generate modulated outputs for such things as motor control.  If CONFIG_STM32_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_STM32_TIMn_PWM   Reserve timer n for use by PWM, n=1,..,8
	CONFIG_STM32_TIMn_ADC   Reserve timer n for use by ADC, n=1,..,8
	CONFIG_STM32_TIMn_ADCm  Reserve timer n to trigger ADCm, n=1,..,8, m=1,..,3
	CONFIG_STM32_TIMn_DAC   Reserve timer n for use by DAC, n=1,..,8
	CONFIG_STM32_TIMn_DACm  Reserve timer n to trigger DACm, n=1,..,8, m=1,..,2

  Others alternate pin mappings available:

	CONFIG_STM32_TIM1_FULL_REMAP
	CONFIG_STM32_TIM1_PARTIAL_REMAP
	CONFIG_STM32_TIM2_FULL_REMAP
	CONFIG_STM32_TIM2_PARTIAL_REMAP_1
	CONFIG_STM32_TIM2_PARTIAL_REMAP_2
	CONFIG_STM32_TIM3_FULL_REMAP
	CONFIG_STM32_TIM3_PARTIAL_REMAP
	CONFIG_STM32_TIM4_REMAP
	CONFIG_STM32_USART1_REMAP
	CONFIG_STM32_USART2_REMAP
	CONFIG_STM32_USART3_FULL_REMAP
	CONFIG_STM32_USART3_PARTIAL_REMAP
	CONFIG_STM32_SPI1_REMAP
	CONFIG_STM32_SPI3_REMAP
	CONFIG_STM32_I2C1_REMAP
	CONFIG_STM32_CAN1_FULL_REMAP
	CONFIG_STM32_CAN1_PARTIAL_REMAP
	CONFIG_STM32_CAN2_REMAP

  STM32F103V 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).
           
           Note: USART1 is connected to a PL2303 serial to USB converter.
           So USART1 is available through USB port labeled CN3 on the board.
           
	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

	CONFIG_STM32_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_STM32_SPI_DMA - Use DMA to improve SPI transfer performance.
	  Cannot be used with CONFIG_STM32_SPI_INTERRUPT.

	CONFIG_SDIO_DMA - Support DMA data transfers.  Requires CONFIG_STM32_SDIO
	  and CONFIG_STM32_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.
    CONFIG_MMCSD_HAVECARDDETECT - Select if SDIO driver card detection
      is 100% accurate  (it is on the  HY-MiniSTM32V)

  HY-MiniSTM32V CAN Configuration

	CONFIG_CAN - Enables CAN support (one or both of CONFIG_STM32_CAN1 or
	  CONFIG_STM32_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_STM32_CAN1 is defined.
	CONFIG_CAN2_BAUD - CAN1 BAUD rate.  Required if CONFIG_STM32_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.

  HY-MiniSTM32V LCD Hardware Configuration  (SSD1289 controler)

    CONFIG_NX_LCDDRIVER - To be defined to include LCD driver
    CONFIG_LCD_LANDSCAPE - Define for 320x240 display "landscape"
      support. In this orientation, the HY-MiniSTM32V's
      LCD used connector is at the right of the display.
      Default is this 320x240 "landscape" orientation
    CONFIG_LCD_PORTRAIT - Define for 240x320 display "portrait"
      orientation support.  In this orientation, the HY-MiniSTM32V's
      LCD used connector is at the bottom of the display. Default is
      320x240 "landscape" orientation.
    CONFIG_LCD_RPORTRAIT - Define for 240x320 display "reverse
      portrait" orientation support.  In this orientation, the
      HY-MiniSTM32V's LCD used connector is at the top of the display.
      Default is 320x240 "landscape" orientation.
    CONFIG_LCD_BACKLIGHT - Define to support an adjustable backlight
      using timer 3.  The granularity of the settings is determined
      by CONFIG_LCD_MAXPOWER.  Requires CONFIG_STM32_TIM3.
    

Configurations
==============

Each HY-MiniSTM32V configuration is maintained in a sudirectory and
can be selected as follow:

	cd tools
	./configure.sh hymini-stm32v/<subdir>
	cd -
	. ./setenv.sh

Where <subdir> is one of the following:

  buttons:
  --------

    Uses apps/examples/buttons to exercise HY-MiniSTM32V buttons and
    button interrupts.
 
    CONFIG_STM32_CODESOURCERYL=y  : CodeSourcery under Linux

  nsh and nsh2:
  ------------
    Configure the NuttShell (nsh) located at examples/nsh.

    Differences between the two NSH configurations:

    =========== ======================= ================================
                nsh                     nsh2
    =========== ======================= ================================
    Toolchain:  Codesourcery for Linux  Codesourcery for Linux (1)
    ----------- ----------------------- --------------------------------
    Loader:     ST bootloader           ST bootloader
    ----------- ----------------------- --------------------------------
    Serial      Debug output: USART1    Debug output: USART1
    Console:    NSH output:   USART1    NSH output:   USART1 (3)
    ----------- ----------------------- --------------------------------
    microSD     Yes                     Yes
    Support
    ----------- ----------------------- --------------------------------
    FAT FS      CONFIG_FAT_LCNAME=y     CONFIG_FAT_LCNAME=y
    Config      CONFIG_FAT_LFN=n        CONFIG_FAT_LFN=y (4)
    ----------- ----------------------- --------------------------------
	LCD Driver  No                      Yes
	Support 
    ----------- ----------------------- --------------------------------
	RTC Support No                      Yes
    ----------- ----------------------- --------------------------------
    Support for No                      Yes
    Built-in
    Apps
    ----------- ----------------------- --------------------------------
    Built-in    None                    apps/examples/nx
    Apps                                apps/examples/nxhello
                                        apps/examples/usbstorage (5)
                                        apps/examples/buttons
                                        apps/examples/nximage
    =========== ======================= ================================

    (1) You will probably need to modify nsh/setenv.sh or nsh2/setenv.sh
        to set up the correct PATH variable for whichever toolchain you
        may use.
    (2) Since DfuSe is assumed, this configuration may only work under
        Cygwin without modification.
    (3) When any other device other than /dev/console is used for a user
        interface, (1) linefeeds (\n) will not be expanded to carriage return
        / linefeeds \r\n). You will need to configure your terminal program
        to account for this. And (2) input is not automatically echoed so
        you will have to turn local echo on.
    (4) Microsoft holds several patents related to the design of
        long file names in the FAT file system.  Please refer to the
        details in the top-level COPYING file.  Please do not use FAT
        long file name unless you are familiar with these patent issues.
    (5) When built as an NSH add-on command (CONFIG_EXAMPLES_USBMSC_BUILTIN=y),
        Caution should be used to assure that the SD drive is not in use when
        the USB storage device is configured.  Specifically, the SD driver
        should be unmounted like:

        nsh> mount -t vfat /dev/mmcsd0 /mnt/sdcard # Card is mounted in NSH
        ...
        nsh> umount /mnd/sdcard                    # Unmount before connecting USB!!!
        nsh> msconn                                # Connect the USB storage device
        ...
        nsh> msdis                                 # Disconnect USB storate device
        nsh> mount -t vfat /dev/mmcsd0 /mnt/sdcard # Restore the mount

        Failure to do this could result in corruption of the SD card format.

  nx:
  ---
    An example using the NuttX graphics system (NX).  This example
    focuses on general window controls, movement, mouse and keyboard
    input.

    CONFIG_STM32_CODESOURCERYW=y  : CodeSourcery under Windows
    CONFIG_LCD_RPORTRAIT=y        : 240x320 reverse portrait

  nxlines:
  ------
    Another example using the NuttX graphics system (NX).   This
    example focuses on placing lines on the background in various
    orientations.

    CONFIG_STM32_CODESOURCERYL=y  : CodeSourcery under Linux
    CONFIG_LCD_RPORTRAIT=y        : 240x320 reverse portrait

  usbserial:
  ---------
    This configuration directory exercises the USB serial class
    driver at examples/usbserial.  See examples/README.txt for
    more information.

    CONFIG_STM32_CODESOURCERYL=y  : CodeSourcery under Linux
    
    USB debug output can be enabled as by changing the following
    settings in the configuration file:

    -CONFIG_DEBUG=n
    -CONFIG_DEBUG_VERBOSE=n
    -CONFIG_DEBUG_USB=n
    +CONFIG_DEBUG=y
    +CONFIG_DEBUG_VERBOSE=y
    +CONFIG_DEBUG_USB=y

    -CONFIG_EXAMPLES_USBSERIAL_TRACEINIT=n
    -CONFIG_EXAMPLES_USBSERIAL_TRACECLASS=n
    -CONFIG_EXAMPLES_USBSERIAL_TRACETRANSFERS=n
    -CONFIG_EXAMPLES_USBSERIAL_TRACECONTROLLER=n
    -CONFIG_EXAMPLES_USBSERIAL_TRACEINTERRUPTS=n
    +CONFIG_EXAMPLES_USBSERIAL_TRACEINIT=y
    +CONFIG_EXAMPLES_USBSERIAL_TRACECLASS=y
    +CONFIG_EXAMPLES_USBSERIAL_TRACETRANSFERS=y
    +CONFIG_EXAMPLES_USBSERIAL_TRACECONTROLLER=y
    +CONFIG_EXAMPLES_USBSERIAL_TRACEINTERRUPTS=y

    By default, the usbserial example uses the Prolific PL2303
    serial/USB converter emulation.  The example can be modified
    to use the CDC/ACM serial class by making the following changes
    to the configuration file:

    -CONFIG_PL2303=y
    +CONFIG_PL2303=n

    -CONFIG_CDCACM=n
    +CONFIG_CDCACM=y

    The example can also be converted to use the alternative
    USB serial example at apps/examples/usbterm by changing the 
    following:

    -CONFIGURED_APPS += examples/usbserial
    +CONFIGURED_APPS += examples/usbterm

    In either the original appconfig file (before configuring)
    or in the final apps/.config file (after configuring).

  usbstorage:
  ----------
    This configuration directory exercises the USB mass storage
    class driver at examples/usbstorage.  See examples/README.txt for
    more information.

    CONFIG_STM32_CODESOURCERYL=y  : CodeSourcery under Linux