第一步：atmega128的片内flash分区描述
在atmega128 datasheet的275页中有分区描述
对应的在284页中，有具体的应用区与boot区的大小设置
注意：Byte address = word address * 2
这里的BOOT区首地址，$F000 = 0x1E000
根据手册中的描述，我们使用JTAG MKII 烧写器通过软件 Avr Studio 4，配置熔丝位 BOOTSZ为00
注意：这里面的4096 words = 8K bytes
第二步：说明一下linker(.xcl)文件的作用
好了，怎么让我们的程序烧写到flash中是在指定的0x1E000处呢？这就需要在link文件中指定CODE区的位置了。
适用于atmega128 bootloader程序的.xcl文件如下：
/* - lnkm128.xcl -
*
* XLINK command file for the ICCAVR C-compiler using the --cpu=m128, -ms
* options. Segments are defined for an ATmega128 whithout external
* memory. It is also possible to "add" external SRAM, EPROM and EEPROM.
*
* Usage: xlink your_file(s) -f lnkm128
*
* File version: $Name: $
*/
/*========================================================================*/
/* NOTE: This file has been modified to be used with the code example in: */
/* AVR106: C functions for reading and writing to Flash memory */
/* Se comments further down in this file, and the application note for */
/* more information. */
/*========================================================================*/
/*====================================================*/
/*
* Constants used down below,
* Do not change these lines,
* if it is not stated otherwise
*/
/* Code (flash) segments */
-D_..X_INTVEC_SIZE=8C /* 4 bytes * 35 vectors */
-D_..X_FLASH_TEND=FF /* End of tiny flash memory */
-D_..X_FLASH_NEND=FFFF /* End of near flash memory */
-D_..X_FLASH_END=1FFFF /* End of flash memory */
/* Internal data memory */
/*
* Change the two lines below to 60(BASE) and FF(TEND)
* if you are running in "mega103 mode"
*/
-D_..X_SRAM_BASE=100 /* Start of ram memory */
-D_..X_SRAM_TEND=100 /* End of tiny ram memory */
-D_..X_SRAM_END=10FF /* End of ram memory */
/* Internal EEPROM */
-D_..X_EEPROM_END=FFF /* End of eeprom memory */
/*====================================================*/
/*
* Modify the lines below to alter the size of the RSTACK, CSTACK and HEAP
* segments. These need to be fine tuned to suit your specific application.
* The ‘_..X_‘ prefix is used by C-SPY as an indication that the label should
* not be displayed in the dissassembly window.
*/
//-D_..X_CSTACK_SIZE=200 /* 512 bytes for auto variables and saved registers. */
//-D_..X_RSTACK_SIZE=40 /* 64 bytes for return addresses, equivalent to 32 */
/* levels of calls, including interrupts. */
//-D_..X_HEAP_SIZE=100 /* 256 bytes of heap. */
-D_..X_CSTACK_SIZE=300 /* 512 bytes for auto variables and saved registers. */
-D_..X_RSTACK_SIZE=40 /* 64 bytes for return addresses, equivalent to 32 */
/* levels of calls, including interrupts. */
-D_..X_HEAP_SIZE=100 /* 256 bytes of heap. */
/*
* Modify these lines if you have an external SRAM connected to the system.
*
* Note: Remember to turn on the external data and address busses in
* __low_level_init if external memory is used.
*/
-D_..X_EXT_SRAM_BASE=_..X_SRAM_BASE
-D_..X_EXT_SRAM_END=_..X_SRAM_END
/*
* Modify these lines if you have an external EPROM connected to the system.
*
* Note: Remember to turn on the external data and address busses in
* __low_level_init if external memory is used.
*/
-D_..X_EXT_EPROM_BASE=_..X_SRAM_BASE
-D_..X_EXT_EPROM_END=_..X_SRAM_END
/*
* Modify these lines if you have an external EEPROM connected to the system.
*
* Note: Remember to turn on the external data and address busses in
* __low_level_init if external memory is used.
*/
-D_..X_EXT_EEPROM_BASE=_..X_SRAM_BASE
-D_..X_EXT_EEPROM_END=_..X_SRAM_END
/*
* The following segments are located in the internal memory of
* the ATmega128. Do not change these lines.
*/
/* Define CPU */
-ca90
/*========================================================================*/
/* How to move the complete project and interrupt table to a Boot Sector. */
/*========================================================================*/
/* This method can be used on any device with boot sectors. */
/* It presumes these defines are predefined: */
/* _..X_INTVEC_SIZE, _..X_FLASH_TEND, */
/* _..X_FLASH_NEND, _..X_FLASH_END */
/*========================================================================*/
/* -1- Find and remove (/comment out) the following section from the */
/* original XCL file. */
/*========================================================================*/
/* Code memory */
//-Z(CODE)INTVEC=0-(_..X_INTVEC_SIZE-1)
/* Fill unused interrupt vector‘s with RETI */
/*
-H1895
-h(CODE)0-_..X_INTVEC_SIZE
-Z(CODE)TINY_F=_..X_INTVEC_SIZE-_..X_FLASH_TEND
-Z(CODE)NEAR_F,SWITCH,DIFUNCT=_..X_INTVEC_SIZE-_..X_FLASH_NEND
-Z(CODE)CODE=_..X_INTVEC_SIZE-_..X_FLASH_END
-Z(FARCODE)FAR_F=_..X_INTVEC_SIZE-_..X_FLASH_END
-Z(CODE)HUGE_F,INITTAB=_..X_INTVEC_SIZE-_..X_FLASH_END
-Z(CODE)TINY_ID,NEAR_ID,CHECKSUM=_..X_INTVEC_SIZE-_..X_FLASH_END
*/
/*========================================================================*/
/* -2- Paste in the following section as a replacement. */
/* -3- Remove the comment marking on the used Boot Sector Size */
/*========================================================================*/
/* Boot Sector Size */
-D_..X_BOOTSEC_SIZE=2000 /* 4096 words */
//-D_..X_BOOTSEC_SIZE=1000 /* 2048 words */
//-D_..X_BOOTSEC_SIZE= 800 /* 1024 words */
//-D_..X_BOOTSEC_SIZE= 400 /* 512 words */
//-D_..X_BOOTSEC_SIZE= 200 /* 256 words */
//-D_..X_BOOTSEC_SIZE= 100 /* 128 words */
-D_..X_DEFSEC_POS=1000
/* Code memory */
-Z(CODE)INTVEC=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+1)-(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE)
-Z(CODE)DEFSEC=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+1+_..X_DEFSEC_POS)-_..X_FLASH_END
/* Fill unused interrupt vector‘s with RETI */
-H1895
-h(CODE)(_..X_FLASH_END-_..X_BOOTSEC_SIZE+1)-(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE)
/*========================================================================*/
/* -4- If the flash size is 32kB or less then; */
/* - Remove the comment marking on following line: */
/*========================================================================*/
//-Z(CODE)NEAR_F,SWITCH,DIFUNCT=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE+1)-_..X_FLASH_NEND
/*========================================================================*/
/* -5- If the flash size is 32kB or less then; */
/* - Remove the SWITCH segment from the following line: */
/*========================================================================*/
-Z(CODE)CODE,SWITCH=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE+1)-_..X_FLASH_END
-Z(FARCODE)FAR_F=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE+1)-_..X_FLASH_END
-Z(CODE)HUGE_F,INITTAB=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE+1)-_..X_FLASH_END
-Z(CODE)TINY_ID,NEAR_ID,CHECKSUM=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE+1)-_..X_FLASH_END
/*========================================================================*/
/*========================================================================*/
/* Internal data memory */
-Z(DATA)TINY_I,TINY_Z,TINY_N=_..X_SRAM_BASE-_..X_SRAM_TEND
-Z(DATA)NEAR_I,NEAR_Z=_..X_SRAM_BASE-_..X_SRAM_END,_..X_EXT_SRAM_BASE-_..X_EXT_SRAM_END
/*
* If external SRAM is available it is possible to place the stacks there.
* However, the external memory is slower than the internal so moving the
* stacks to the external memory will degrade the system performance.
*/
-Z(DATA)RSTACK+_..X_RSTACK_SIZE=_..X_SRAM_BASE-_..X_SRAM_END /* ,_..X_EXT_SRAM_BASE-_..X_EXT_SRAM_END */
-Z(DATA)CSTACK+_..X_CSTACK_SIZE=_..X_SRAM_BASE-_..X_SRAM_END /* ,_..X_EXT_SRAM_BASE-_..X_EXT_SRAM_END */
/*
* If external SRAM is available it might be a good idea to move the
* heap segment there, i.e. remove the _..X_SRAM_BASE-_..X_SRAM_END range.
*/
-Z(DATA)HEAP+_..X_HEAP_SIZE=_..X_SRAM_BASE-_..X_SRAM_END,_..X_EXT_SRAM_BASE-_..X_EXT_SRAM_END
/* Internal eeprom memory */
-Z(XDATA)EEPROM_I,EEPROM_N=0-_..X_EEPROM_END
/*
* The following segment definitions are only used if external memory is
* connected to the AVR controller.
*/
/* External EPROM */
-Z(CONST)NEAR_C=_..X_EXT_EPROM_BASE-_..X_EXT_EPROM_END
/* External EEPROM */
-Z(DATA)NEAR_N=_..X_EXT_EEPROM_BASE-_..X_EXT_EEPROM_END
/* Select reduced "printf" support to reduce library size.
See configuration section in manual concerning printf/sprintf. */
/*Dlib*/
-e_Printf_1=_Printf
/*Clib*/
-e_small_write=_formatted_write
-e_small_write_P=_formatted_write_P
/* Disable floating-point support in "scanf" to reduce library size.
See configuration section in manual concerning scanf/sscanf */
/*Dlib*/
-e_Scanf_1=_Scanf
/*Clib*/
-e_medium_read=_formatted_read
-e_medium_read_P=_formatted_read_P
/* Suppress one warning which is not relevant for this processor */
-w29
/* Code will now reside in file aout.a90 or aout.d90, unless -o is specified */
/* .d90 is the default if debug system is linked (option -r) */
/* .a90 is the default without debugging. Default format is -Fmotorola */
其中
-D_..X_BOOTSEC_SIZE=2000 /* 4096 words */
确定了BOOT区的大小为4096字，与我们设置的BOOTSZ = 00正好吻合。
然后
-Z(CODE)INTVEC=(_..X_FLASH_END-_..X_BOOTSEC_SIZE+1)-(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE) -h(CODE)(_..X_FLASH_END-_..X_BOOTSEC_SIZE+1)-(_..X_FLASH_END-_..X_BOOTSEC_SIZE+_..X_INTVEC_SIZE)
表示中断向量区的范围从0x1E000 ~ 0x1E08B，并将其填充
具体参数项，可以参考AVR的帮助文档 Linker and library Tools reference guide.
参考：ATMEL的官方应用文档的AVR106号应用笔记
http://www.atmel.com/dyn/products/app_notes.asp?family_id=607
第三步：bootloader程序，linker文件加载
1）将以上代码保存为lnkm128.xcl，并放于工程目录下
2）通过配置工程 Linker->Config->Override default将该文件加载进来
第四步：验证生成的hex文件是否将代码编译到了片内flash的0x1E000地址处
021000 -> 确定偏移段地址为0x1000
10E000 -> 确定段内地址从 0xE000开始
经计算实际地址为 0x10000 + 0xE000 = 0x1E000
时间： 2024-10-19 00:14:29