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_ARM_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery under Windows
CONFIG_ARM_TOOLCHAIN_CODESOURCERYL=y : CodeSourcery under Linux
CONFIG_ARM_TOOLCHAIN_DEVKITARM=y : devkitARM under Windows
CONFIG_ARM_TOOLCHAIN_BUILDROOT=y : NuttX buildroot under Linux or Cygwin (default)
CONFIG_ARM_TOOLCHAIN_GNU_EABIL : Generic arm-none-eabi toolchain

You may also have to modify the PATH environment variable 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= to make, where 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.

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://developer.arm.com/open-source/gnu-toolchain/gnu-rm

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

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. You may have to build NuttX
one time from the Cygwin command line in order to obtain the pre-built
startup object needed by an IDE.

NuttX buildroot Toolchain
^^^^^^^^^^^^^^^^^^^^^^^^^

A GNU GCC-based toolchain is assumed. The PATH environment variable 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
Bitbucket download site (https://bitbucket.org/nuttx/buildroot/downloads/).
This GNU toolchain builds and executes in the Linux or Cygwin environment.

1. You must have already configured Nuttx in /nuttx.

tools/configure.sh ea3152/

2. Download the latest buildroot package into

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

4. cd /buildroot

5. cp configs/arm926t-defconfig-4.2.4 .config

6. make oldconfig

7. make

8. Make sure 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:

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

NOTES:

1. You will need to 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_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_BUTTONS - Enable support for buttons. Unique to board architecture.

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:

tools/configure.sh ea3152/

Where 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.