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

All testing has been conducted using the NuttX buildroot toolchain. To use a different toolchain, you simply need to modify the configuration. As an example:

CONFIG_ARM_TOOLCHAIN_GNU_EABI : Generic arm-none-eabi toolchain

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

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 paths: 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 <some-dir>/nuttx.

   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 boards/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 boards/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 boards/arm/lpc31xx/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 boards/arm/lpc31xx/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 boards/arm/lpc31xx/ea3152/tools doesn't seem to work.  As a result,
   the CRC is currently disabled in the header:

   RCS file: /cvsroot/nuttx/nuttx/boards/arm/lpc31xx/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
  occurrences of `cygpath -w blablabla` to just blablabla

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

boards/arm/lpc31xx/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 boards/ 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
  determine 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:<subdir>

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.