我正在处理来自NXP的新型微控制器LPC4088。我需要两周时间研究和编写外设的工作示例:IOCONFIG、GPIO、TIMERS、PWM和ADC。请查看我的存储库here。这是您了解我的工作方式和技能水平的方式。
到目前为止,我可以简单地禁用中断并在没有中断的情况下工作。现在我想处理需要中断的UART外设设备。我从未编写过中断程序,但对ARM中断有一些了解。目前我正在学习这两个文档:
- LPC4088用户指南(NVIC p.80 & UART1 p.461), - Cortex-M4设备通用用户手册。
我正在考虑使用Segger Jlink对启动代码进行反向工程,并在那里修复异常向量,但除了编写自己的开源启动代码之外,一定还有其他方法...因此,您有任何建议或示例会更好。
到目前为止,我可以简单地禁用中断并在没有中断的情况下工作。现在我想处理需要中断的UART外设设备。我从未编写过中断程序,但对ARM中断有一些了解。目前我正在学习这两个文档:
- LPC4088用户指南(NVIC p.80 & UART1 p.461), - Cortex-M4设备通用用户手册。
我意识到需要学习 ARM Cortex-M4 微处理器,除了已经掌握的 LPC4088 微控制器。我知道应该将 ARM 异常向量放在程序的开头,通常是在启动代码中。但是我不知道如何做到这一点,因为我得到的是已编译的启动代码(目标文件),其中可能定义了异常向量和复位处理程序, 将 C 栈设置并跳转到用户编写的 C 源代码中的 main() 函数。
使用 GCC ARM 编译器编译我的程序后,我总是得到以下提示,这也必须是我不理解的关键,因为我没有直接使用 ARM mcpu 的经验:
*****
***** You must modify vector checksum value in *.bin and *.hex files.
*****
我正在考虑使用Segger Jlink对启动代码进行反向工程,并在那里修复异常向量,但除了编写自己的开源启动代码之外,一定还有其他方法...因此,您有任何建议或示例会更好。
添加:我真的很努力地寻找了启动代码的源代码,但是没有找到。这就是我得到的内容:
/* Linker script for mbed LPC1768 */
/* Linker script to configure memory regions. */
MEMORY
{
FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 512K
RAM (rwx) : ORIGIN = 0x100000E8, LENGTH = (64K - 0xE8)
USB_RAM(rwx) : ORIGIN = 0x20000000, LENGTH = 16K
ETH_RAM(rwx) : ORIGIN = 0x20004000, LENGTH = 16K
}
/* Linker script to place sections and symbol values. Should be used together
* with other linker script that defines memory regions FLASH and RAM.
* It references following symbols, which must be defined in code:
* Reset_Handler : Entry of reset handler
*
* It defines following symbols, which code can use without definition:
* __exidx_start
* __exidx_end
* __etext
* __data_start__
* __preinit_array_start
* __preinit_array_end
* __init_array_start
* __init_array_end
* __fini_array_start
* __fini_array_end
* __data_end__
* __bss_start__
* __bss_end__
* __end__
* end
* __HeapLimit
* __StackLimit
* __StackTop
* __stack
*/
ENTRY(Reset_Handler)
SECTIONS
{
.text :
{
KEEP(*(.isr_vector))
*(.text*)
KEEP(*(.init))
KEEP(*(.fini))
/* .ctors */
*crtbegin.o(.ctors)
*crtbegin?.o(.ctors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors)
*(SORT(.ctors.*))
*(.ctors)
/* .dtors */
*crtbegin.o(.dtors)
*crtbegin?.o(.dtors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors)
*(SORT(.dtors.*))
*(.dtors)
*(.rodata*)
KEEP(*(.eh_frame*))
} > FLASH
.ARM.extab :
{
*(.ARM.extab* .gnu.linkonce.armextab.*)
} > FLASH
__exidx_start = .;
.ARM.exidx :
{
*(.ARM.exidx* .gnu.linkonce.armexidx.*)
} > FLASH
__exidx_end = .;
__etext = .;
.data : AT (__etext)
{
__data_start__ = .;
Image$$RW_IRAM1$$Base = .;
*(vtable)
*(.data*)
. = ALIGN(4);
/* preinit data */
PROVIDE (__preinit_array_start = .);
KEEP(*(.preinit_array))
PROVIDE (__preinit_array_end = .);
. = ALIGN(4);
/* init data */
PROVIDE (__init_array_start = .);
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE (__init_array_end = .);
. = ALIGN(4);
/* finit data */
PROVIDE (__fini_array_start = .);
KEEP(*(SORT(.fini_array.*)))
KEEP(*(.fini_array))
PROVIDE (__fini_array_end = .);
. = ALIGN(4);
/* All data end */
__data_end__ = .;
} > RAM
.bss :
{
__bss_start__ = .;
*(.bss*)
*(COMMON)
__bss_end__ = .;
Image$$RW_IRAM1$$ZI$$Limit = . ;
} > RAM
.heap :
{
__end__ = .;
end = __end__;
*(.heap*)
__HeapLimit = .;
} > RAM
/* .stack_dummy section doesn't contains any symbols. It is only
* used for linker to calculate size of stack sections, and assign
* values to stack symbols later */
.stack_dummy :
{
*(.stack)
} > RAM
/* Set stack top to end of RAM, and stack limit move down by
* size of stack_dummy section */
__StackTop = ORIGIN(RAM) + LENGTH(RAM);
__StackLimit = __StackTop - SIZEOF(.stack_dummy);
PROVIDE(__stack = __StackTop);
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed with stack")
/* Code can explicitly ask for data to be
placed in these higher RAM banks where
they will be left uninitialized.
*/
.AHBSRAM0 (NOLOAD):
{
Image$$RW_IRAM2$$Base = . ;
*(AHBSRAM0)
Image$$RW_IRAM2$$ZI$$Limit = .;
} > USB_RAM
.AHBSRAM1 (NOLOAD):
{
Image$$RW_IRAM3$$Base = . ;
*(AHBSRAM1)
Image$$RW_IRAM3$$ZI$$Limit = .;
} > ETH_RAM
}
还有一个Makefile文件,看起来像这样,并且贡献了我在每次编译结束时得到的提示:
# This file was automagically generated by mbed.org. For more information,
# see http://mbed.org/handbook/Exporting-to-GCC-ARM-Embedded
GCC_BIN =
PROJECT = executaable
OBJECTS = ./main.o
SYS_OBJECTS = ./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM/startup_LPC408x.o ./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM/retarget.o ./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM/system_LPC407x_8x_177x_8x.o ./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM/board.o ./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM/cmsis_nvic.o
INCLUDE_PATHS = -I. -I./mbed -I./mbed/TARGET_LPC4088 -I./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM -I./mbed/TARGET_LPC4088/TARGET_NXP -I./mbed/TARGET_LPC4088/TARGET_NXP/TARGET_LPC408X -I./mbed/TARGET_LPC4088/TARGET_NXP/TARGET_LPC408X/TARGET_LPC4088
LIBRARY_PATHS = -L./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM
LIBRARIES = -lmbed
LINKER_SCRIPT = ./mbed/TARGET_LPC4088/TOOLCHAIN_GCC_ARM/LPC4088.ld
###############################################################################
AS = $(GCC_BIN)arm-none-eabi-as
CC = $(GCC_BIN)arm-none-eabi-gcc
CPP = $(GCC_BIN)arm-none-eabi-g++
LD = $(GCC_BIN)arm-none-eabi-gcc
OBJCOPY = $(GCC_BIN)arm-none-eabi-objcopy
OBJDUMP = $(GCC_BIN)arm-none-eabi-objdump
SIZE = $(GCC_BIN)arm-none-eabi-size
CPU = -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=softfp
CC_FLAGS = $(CPU) -c -g -fno-common -fmessage-length=0 -Wall -fno-exceptions -ffunction-sections -fdata-sections -fomit-frame-pointer
CC_FLAGS += -MMD -MP
CC_SYMBOLS = -DTARGET_LPC4088 -DTARGET_M4 -DTARGET_CORTEX_M -DTARGET_NXP -DTARGET_LPC408X -DTOOLCHAIN_GCC_ARM -DTOOLCHAIN_GCC -D__CORTEX_M4 -DARM_MATH_CM4 -D__FPU_PRESENT=1 -DMBED_BUILD_TIMESTAMP=1429428454.91 -D__MBED__=1
LD_FLAGS = $(CPU) -Wl,--gc-sections --specs=nano.specs -u _printf_float -u _scanf_float -Wl,--wrap,main
LD_FLAGS += -Wl,-Map=$(PROJECT).map,--cref
LD_SYS_LIBS = -lstdc++ -lsupc++ -lm -lc -lgcc -lnosys
ifeq ($(DEBUG), 1)
CC_FLAGS += -DDEBUG -O0
else
CC_FLAGS += -DNDEBUG -Os
endif
all: $(PROJECT).bin $(PROJECT).hex
clean:
rm -f $(PROJECT).bin $(PROJECT).elf $(PROJECT).hex $(PROJECT).map $(PROJECT).lst $(OBJECTS) $(DEPS)
.s.o:
$(AS) $(CPU) -o $@ $<
.c.o:
$(CC) $(CC_FLAGS) $(CC_SYMBOLS) -std=gnu99 $(INCLUDE_PATHS) -o $@ $<
.cpp.o:
$(CPP) $(CC_FLAGS) $(CC_SYMBOLS) -std=gnu++98 -fno-rtti $(INCLUDE_PATHS) -o $@ $<
$(PROJECT).elf: $(OBJECTS) $(SYS_OBJECTS)
$(LD) $(LD_FLAGS) -T$(LINKER_SCRIPT) $(LIBRARY_PATHS) -o $@ $^ $(LIBRARIES) $(LD_SYS_LIBS) $(LIBRARIES) $(LD_SYS_LIBS)
@echo ""
@echo "*****"
@echo "***** You must modify vector checksum value in *.bin and *.hex files."
@echo "*****"
@echo ""
$(SIZE) $@
$(PROJECT).bin: $(PROJECT).elf
@$(OBJCOPY) -O binary $< $@
$(PROJECT).hex: $(PROJECT).elf
@$(OBJCOPY) -O ihex $< $@
$(PROJECT).lst: $(PROJECT).elf
@$(OBJDUMP) -Sdh $< > $@
lst: $(PROJECT).lst
size:
$(SIZE) $(PROJECT).elf
DEPS = $(OBJECTS:.o=.d) $(SYS_OBJECTS:.o=.d)
-include $(DEPS)