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