README
^^^^^^

  This README file discusses the port of NuttX to the Embedded Artists
  EA3152 board.

Contents
^^^^^^^^

  o Development Environment
  o GNU Toolchain Options
  o IDEs
  o NuttX buildroot Toolchain
  o Boot Sequence
  o Image Format
  o Image Download to ISRAM
  o Using OpenOCD and GDB
  o ARM/EA3152-specific Configuration Options
  o 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.

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,
  4. The NuttX buildroot Toolchain (see below), or
  5. Any generic arm-none-eabi GNU toolchain.

  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_LPC31_CODESOURCERYW=y  : CodeSourcery under Windows
    CONFIG_LPC31_CODESOURCERYL=y  : CodeSourcery under Linux
    CONFIG_LPC31_DEVKITARM=y      : devkitARM under Windows
    CONFIG_LPC31_BUILDROOT=y      : NuttX buildroot under Linux or Cygwin (default)
    CONFIG_ARM_TOOLCHAIN_GNU_EABIL : Generic arm-none-eabi toolchain

  If you are not using CONFIG_LPC31_BUILDROOT, then you may also have to modify
  the PATH in the setenv.h file if your make cannot find the tools.

  The toolchain may also be set using the kconfig-mconf utility (make menuconfig)
  or by passing CONFIG_ARM_TOOLCHAIN=<toolchain> to make, where <toolchain> is one
  of CODESOURCERYW, CODESOURCERYL, DEVKITARM, BUILDROOT or GNU_EABI as described
  above.

  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.

       MKDEP                = $(TOPDIR)/tools/mknulldeps.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.
 
  Generic arm-none-eabi GNU Toolchain
  -----------------------------------
  There are a number of toolchain projects providing support for ARMv4/v5
  class processors, including:

    GCC ARM Embedded
      https://launchpad.net/gcc-arm-embedded

    Summon ARM Toolchain
      https://github.com/esden/summon-arm-toolchain

    Yagarto
      http://www.yagarto.de

  Others exist for various Linux distributions, MacPorts, etc.  Any version
  based on GCC 4.6.3 or later should work.

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/lpc31xx,
     arch/arm/src/common, arch/arm/src/arm, 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/lpc31xx/lpc31_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/projects/nuttx/files/buildroot/).
  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 ea3152/<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/arm926t-defconfig-4.2.4 .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.

Boot Sequence
^^^^^^^^^^^^^
  LPC315x has on chip bootrom which loads properly formatted images from multiple
  sources into SRAM.  These sources include including SPI Flash, NOR Flash, UART,
  USB, SD Card, and NAND Flash.

  In all configurations, NuttX is loaded directly into ISRAM.  NuttX is linked
  to execute from ISRAM, regardless of the boot source.

Image Format
^^^^^^^^^^^^

  In order to use the bootrom bootloader, a special header must be added to the
  beginning of the binary image that includes information about the binary (things
  like the entry point, the size, and CRC's to verify the image.

  NXP provides a Windows program to append such a header to the binary image.
  However, (1) that program won't run under Linux, and (2) when I try it under
  WinXP, Symantec immediately claims that the program is misbehaving and deletes
  it!

  To work around both of these issues, I have created a small program under
  configs/ea3152/tools to add the header.  This program can be built under
  either Linux or Cygwin (and probably other tool environments as well).  That
  tool can be built as follows:

  - cd configs/ea3152/tools
  - make

  Then, to build the NuttX binary ready to load with the bootloader, just
  following these steps:

  - cd tools/                     # Configure Nuttx
  - ./configure.sh ea3152/ostest  # (using the ostest configuration for this example)
  - cd ..                         # Set up environment
  - . ./setenv.sh                 # (see notes below)
  - make                          # Make NuttX.  This will produce nuttx.bin
  - mklpc.sh                      # Make the bootloader binary (nuttx.lpc)

  NOTES:
  
    1. setenv.sh just sets up pathes to the toolchain and also to
       configs/ea3152/tools where mklpc.sh resides. Use of setenv.sh is optional.
       If you don't use setenv.sh, then just set your PATH variable appropriately or
       use the full path to mklpc.sh in the final step.
    2. You can instruct Symantec to ignore the errors and it will stop quarantining
       the NXP program.
    3. The CRC32 logic in configs/ea3152/tools doesn't seem to work.  As a result,
       the CRC is currently disabled in the header:

       RCS file: /cvsroot/nuttx/nuttx/configs/ea3152/tools/lpchdr.c,v
       retrieving revision 1.2
       diff -r1.2 lpchdr.c
       264c264
       <   g_hdr.imageType       = 0x0000000b;
       ---
       >   g_hdr.imageType       = 0x0000000a;

Image Download to ISRAM
^^^^^^^^^^^^^^^^^^^^^^^

Assuming that you already have the FTDI driver installed*, then here is the
are the steps that I use for loading new code into the EA3152:

- Create the bootloader binary, nuttx.lpc, as described above.
- Connected the EA3152 using the FTDI USB port (not the lpc3152 USB port)
  This will power up the EA3152 and start the bootloader.
- Start a terminal emulator (such as TeraTerm) at 115200 8NI.
- Reset the EA3152 and you should see:
  LPC31xx READY FOR PLAIN IMAGE>
- Send the nuttx.lpc file and you should see:
  Download finished

That will load the NuttX binary into ISRAM and attempt to execute it.

*See the LPC315x documentation if you do not have the FTDI driver installed.

Using OpenOCD and GDB
^^^^^^^^^^^^^^^^^^^^^

  I have been using the Olimex ARM-USB-OCD JTAG debugger with the EA3152
  (http://www.olimex.com).  The OpenOCD configuration file is here:
  tools/armusbocb.cfg.  There is also a script on the tools directory that
  I used to start the OpenOCD daemon on my system called oocd.sh.  That
  script would probably require some modifications to work in another
  environment:
  
    - possibly the value of OPENOCD_PATH
    - If you are working under Linux you will need to change any
      occurances of `cygpath -w blablabla` to just blablabla

  Then you should be able to start the OpenOCD daemon like:

    configs/ea3152/tools/oocd.sh $PWD

  Where it is assumed that you are executing oocd.sh from the top level
  directory where NuttX is installed.

  Once the OpenOCD daemon has been started, you can connect to it via
  GDB using the following GDB command:

   arm-nuttx-elf-gdb
   (gdb) target remote localhost:3333

  And you can load the NuttX ELF file:

   (gdb) symbol-file nuttx
   (gdb) load nuttx

ARM/EA3152-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_ARM926EJS=y

    CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory

       CONFIG_ARCH_CHIP=lpc31xx

    CONFIG_ARCH_CHIP_name - For use in C code

       CONFIG_ARCH_CHIP_LPC3152

    CONFIG_ARCH_BOARD - Identifies the configs subdirectory and
       hence, the board that supports the particular chip or SoC.

       CONFIG_ARCH_BOARD=ea3152

    CONFIG_ARCH_BOARD_name - For use in C code

       CONFIG_ARCH_BOARD_EA3152

    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 - For most ARM9 architectures, this describes the
      size of installed DRAM.  For the LPC315X, it is used only to
      deterimine how to map the executable regions.  It is SDRAM size
      only if you are executing out of the external SDRAM; or it could
      be NOR FLASH size, external SRAM size, or internal SRAM size.

    CONFIG_RAM_START - The start address of installed DRAM (physical)

    CONFIG_RAM_VSTART - The startaddress of DRAM (virtual)

    CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to boards that
       have LEDs

    CONFIG_ARCH_IRQPRIO - The LPC315x supports interrupt prioritization

    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_BOOTLOADER - Set if you are using a bootloader.

    CONFIG_ARCH_LEDS -  Use LEDs to show state. Unique to board architecture.

    CONFIG_ARCH_BUTTONS -  Enable support for buttons. 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.
    CONFIG_ARCH_DMA - Support DMA initialization
    CONFIG_ARCH_LOWVECTORS - define if vectors reside at address 0x0000:00000
      Undefine if vectors reside at address 0xffff:0000
    CONFIG_ARCH_ROMPGTABLE - A pre-initialized, read-only page table is available.
      If defined, then board-specific logic must also define PGTABLE_BASE_PADDR,
      PGTABLE_BASE_VADDR, and all memory section mapping in a file named
      board_memorymap.h.

  Individual subsystems can be enabled:

    CONFIG_LPC31_MCI, CONFIG_LPC31_SPI, CONFIG_LPC31_UART

  External memory available on the board (see also CONFIG_MM_REGIONS)

    CONFIG_LPC31_EXTSRAM0 - Select if external SRAM0 is present
    CONFIG_LPC31_EXTSRAM0HEAP - Select if external SRAM0 should be
      configured as part of the NuttX heap.
    CONFIG_LPC31_EXTSRAM0SIZE - Size (in bytes) of the installed
      external SRAM0 memory
    CONFIG_LPC31_EXTSRAM1 - Select if external SRAM1 is present
    CONFIG_LPC31_EXTSRAM1HEAP - Select if external SRAM1 should be
      configured as part of the NuttX heap.
    CONFIG_LPC31_EXTSRAM1SIZE - Size (in bytes) of the installed
      external SRAM1 memory
    CONFIG_LPC31_EXTDRAM - Select if external SDRAM is present
    CONFIG_LPC31_EXTDRAMHEAP - Select if external SDRAM should be
      configured as part of the NuttX heap.
    CONFIG_LPC31_EXTDRAMSIZE - Size (in bytes) of the installed
      external SDRAM memory
    CONFIG_LPC31_EXTNAND - Select if external NAND is present
    CONFIG_LPC31_EXTNANDSIZE - Size (in bytes) of the installed
      external NAND memory

  LPC315X specific device driver settings

    CONFIG_UART_SERIAL_CONSOLE - selects the UART for the
      console and ttys0
    CONFIG_UART_RXBUFSIZE - Characters are buffered as received.
      This specific the size of the receive buffer
    CONFIG_UART_TXBUFSIZE - Characters are buffered before
      being sent.  This specific the size of the transmit buffer
    CONFIG_UART_BAUD - The configure BAUD of the UART.  Must be
    CONFIG_UART_BITS - The number of bits.  Must be either 7 or 8.
    CONFIG_UART_PARTIY - 0=no parity, 1=odd parity, 2=even parity
    CONFIG_UART_2STOP - Two stop bits

Configurations
^^^^^^^^^^^^^^

Each EA3152 configuration is maintained in a sub-directory and can be
selected as follow:

    cd tools
    ./configure.sh ea3152/<subdir>
    cd -
    . ./setenv.sh

Where <subdir> is one of the following:

  ostest:
    This configuration directory, performs a simple OS test using
    examples/ostest.  By default, this project assumes that you are
    using the DFU bootloader.

