426f8f0214
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5623 42af7a65-404d-4744-a932-0658087f49c3
132 lines
4.3 KiB
Plaintext
132 lines
4.3 KiB
Plaintext
README.txt
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==========
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This README file discusses the port of NuttX to the WaveShare Open1788 board:
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See http://wvshare.com/product/Open1788-Standard.htm. This board features the
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NXP LPC1788 MCU
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CONTENTS
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========
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o FPU
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o Configuration
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FPU
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===
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FPU Configuration Options
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-------------------------
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There are two version of the FPU support built into the LPC17xx port.
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1. Lazy Floating Point Register Save.
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This is an untested implementation that saves and restores FPU registers
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only on context switches. This means: (1) floating point registers are
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not stored on each context switch and, hence, possibly better interrupt
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performance. But, (2) since floating point registers are not saved,
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you cannot use floating point operations within interrupt handlers.
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This logic can be enabled by simply adding the following to your .config
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file:
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CONFIG_ARCH_FPU=y
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2. Non-Lazy Floating Point Register Save
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Mike Smith has contributed an extensive re-write of the ARMv7-M exception
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handling logic. This includes verified support for the FPU. These changes
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have not yet been incorporated into the mainline and are still considered
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experimental. These FPU logic can be enabled with:
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CONFIG_ARCH_FPU=y
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CONFIG_ARMV7M_CMNVECTOR=y
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You will probably also changes to the ld.script in if this option is selected.
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This should work:
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-ENTRY(_stext)
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+ENTRY(__start) /* Treat __start as the anchor for dead code stripping */
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+EXTERN(_vectors) /* Force the vectors to be included in the output */
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CFLAGS
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------
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Only the Atollic toolchain has built-in support for the Cortex-M4 FPU. You will see
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the following lines in each Make.defs file:
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ifeq ($(CONFIG_STM32_ATOLLIC_LITE),y)
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# Atollic toolchain under Windows
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...
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ifeq ($(CONFIG_ARCH_FPU),y)
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ARCHCPUFLAGS = -mcpu=cortex-m4 -mthumb -march=armv7e-m -mfpu=fpv4-sp-d16 -mfloat-abi=hard
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else
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ARCHCPUFLAGS = -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
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endif
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endif
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If you are using a toolchain other than the Atollic toolchain, then to use the FPU
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you will also have to modify the CFLAGS to enable compiler support for the ARMv7-M
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FPU. As of this writing, there are not many GCC toolchains that will support the
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ARMv7-M FPU.
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As a minimum you will need to add CFLAG options to (1) enable hardware floating point
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code generation, and to (2) select the FPU implementation. You might try the same
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options as used with the Atollic toolchain in the Make.defs file:
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ARCHCPUFLAGS = -mcpu=cortex-m4 -mthumb -march=armv7e-m -mfpu=fpv4-sp-d16 -mfloat-abi=hard
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Configuration Changes
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---------------------
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Below are all of the configuration changes that I had to make to configs/stm3240g-eval/nsh2
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in order to successfully build NuttX using the Atollic toolchain WITH FPU support:
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-CONFIG_ARCH_FPU=n : Enable FPU support
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+CONFIG_ARCH_FPU=y
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-CONFIG_STM32_CODESOURCERYW=y : Disable the CodeSourcery toolchain
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+CONFIG_STM32_CODESOURCERYW=n
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-CONFIG_STM32_ATOLLIC_LITE=n : Enable *one* the Atollic toolchains
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CONFIG_STM32_ATOLLIC_PRO=n
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-CONFIG_STM32_ATOLLIC_LITE=y : The "Lite" version
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CONFIG_STM32_ATOLLIC_PRO=n : The "Pro" version
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-CONFIG_INTELHEX_BINARY=y : Suppress generation FLASH download formats
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+CONFIG_INTELHEX_BINARY=n : (Only necessary with the "Lite" version)
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-CONFIG_HAVE_CXX=y : Suppress generation of C++ code
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+CONFIG_HAVE_CXX=n : (Only necessary with the "Lite" version)
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See the section above on Toolchains, NOTE 2, for explanations for some of
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the configuration settings. Some of the usual settings are just not supported
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by the "Lite" version of the Atollic toolchain.
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CONFIGURURATION
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===============
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ostest
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------
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This configuration directory, performs a simple OS test using
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apps/examples/ostest.
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NOTES:
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1. This configuration uses the mconf-based configuration tool. To
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change this configuration using that tool, you should:
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a. Build and install the kconfig-mconf tool. See nuttx/README.txt
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and misc/tools/
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b. Execute 'make menuconfig' in nuttx/ in order to start the
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reconfiguration process.
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2. Uses the older, OABI, buildroot toolchain. But that is easily
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reconfigured:
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CONFIG_ARMV7M_TOOLCHAIN_BUILDROOT=y : Buildroot toolchain
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CONFIG_ARMV7M_OABI_TOOLCHAIN=y : Older, OABI toolchain
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