The execution process before executing the main function after the DSP chip is powered on

With tms320f28377d For example ：

Suppose we create a project test;

The documents to be noted in this project include （ See the picture 1）：

1、 main.c file ;

2、 DSP Used to connect to .coff（ Executable file ） Of  .cmd file ;

3、 28377 Model appropriate F2837xD_CodeStartBranch.asm file

 

chart 1

main The specific contents of the procedure are as follows （ See the picture 2）： Just one main application , Random content ;

 

chart 2

When we burn the project into dsp On chip in a chip FLASH when ,dsp How to execute the code in the chip when powered on （ Code execution process ）;

 

First , stay dsp In the online debugging state , Get into debug Interface , open view In the menu bar Disassembly Options （ See the picture 3）; Here we can view the film flash Assembly code corresponding to different addresses on ;

 

chart 3

Open as follows ： We click debug In the interface CPU Reset after ;

At this point, the chip restarts ; The running position of the code after restart is on-chip flash Address 0x3ff16a（ See the picture 4）, The code at this location is Ti Procedures that have been cured before leaving the factory , The function is to complete the bottom register , Environment configuration of stack, etc ;

 

chart 4

Next , wait for Ti At the bottom boot After the program is initialized ,DSP The chip will jump to 0x80000 To execute the user's first instruction ; We're at the address 0x80000 Set a breakpoint at ; Click continue （ See the picture 5）;

 

chart 5

here , The program stops at the set breakpoint 0x80000 It's about , This is a dsp The bottom layer is powered on after execution boot after , Address of the first user instruction executed ;DSP Default flash start-up ,dsp Start up boot After the initialization , Program PC Set to flash Address of the 0x80000 To execute the user's first instruction , namely F2837xD_CodeStartBranch.asm In the document code_start function （ See the picture 6）; Observe flash stay 0x80000 Memory contents at , There is only one jump instruction in the program 0048 201C （ The machine code means 004/ Jump to 8201C It's about ）; namely LB  _c_int00, Jump to function _c_int00;（ Be careful ： Suppose we configure cmd file ;BEGEIN:           origin=0x082000,length=0x000002; When we connect the emulator online , The program can run normally , But when we don't connect the emulator , keep dsp The chip is powered on when the emulator is not connected , here , The program has indeed been burned into dsp Of flash In the chip , But the chip will not work normally after it is powered on ; because ,dsp At the completion of boot And then I'll run 0x80000 To execute the user's first instruction , And ours cmd In file ：code_start：>BEGIN The first command of power on operation is written in flash 0x82000 It's about , and 0x80000 There is no executable code at , So our chip will not run after it is powered on ）

 

chart 6

stay Disassembly Click step by step , The next instruction the program runs is _c_int00 function ; The function address is

0x8201C, Consistent with the jump address of the machine code （ See the picture 7）; The main functions of this function are ： Initialize registers and stacks for application layer code written by users ; Continue to step down ;（_c_int00 Save in boot28.asm in , This file is a library file , Not within the scope of user creation ）

 

chart 7

You can find that the program runs to LCR __args_main This assembly instruction （ Still in _c_int00 Function ）; This Assembly statement means to jump to __args_main Function and return （ if main Function cannot return, then the function cannot return ）;

Continue to click step by step , Get into __args_main Function （ See the picture 8）;

 

chart 8

You can find ,__args_main The last instruction the function executes is written by the user main function ;（__args_main Function saved in args_main.c in , This file is a library file , Not within the scope of user creation ）（ See the picture 9）

 

chart 9

 

thus , We can DSP The process of power on operation is summarized as follows ：

 

chart 10