DSP程序Flash程序下载到RAM中运行

 基于DSP的嵌入式系统开发中，存储资源特别是片内高速存储资源有限，在算法系统集成时Memory的管理对于提高整个系统的优化是非常重要的。

程序区：最大原则是将经常调度使用的算法模块放片内,TI的CCS中提供了#pragma CODE_SECTION，可以把需要单独控制存放的函数段从.text段中独立出来，从而在.cmd文件中对这些函数段进行单独物理地址映射。

程序烧到flash中后可以运行但是速度慢，如何将程序从flash中下载到RAM中运行？

 

1.先在cmd文件中进行配置

secureRamFuncs : LOAD = FLASH_E, PAGE = 0 /* Used by InitFlash() in SysCtrl.c */

RUN = PRAMH0, PAGE = 0

LOAD_START(_secureRamFuncs_loadstart),

LOAD_END(_secureRamFuncs_loadend),

RUN_START(_secureRamFuncs_runstart)

 

2.实现函数处,可以找demo参考

/**********************************************************************

* Function: InitFlash()

* Description: Initializes the F281x flash timing registers.

* Notes:

* 1) This function MUST be executed out of RAM. Executing it out of

* OTP/FLASH will produce unpredictable results.

* 2) The flash registers are code security module protected. Therefore,

* you must either run this function from L0/L1 RAM, or you must

* first unlock the CSM. Note that unlocking the CSM as part of

* the program flow can compromise the code security.

* 3) Final flash characterization needs to be performed by TI. The

* below settings may not meet final specifications, and are for

* example purposes only. Check the latest device datasheet for

* TMS qualified specifications.

**********************************************************************/

#pragma CODE_SECTION(InitFlash, "secureRamFuncs")

void InitFlash(void)

{

asm(" EALLOW"); // Enable EALLOW protected register access

FlashRegs.FPWR.bit.PWR = 3; // Pump and bank set to active mode

FlashRegs.FSTATUS.bit.V3STAT = 1; // Clear the 3VSTAT bit

FlashRegs.FSTDBYWAIT.bit.STDBYWAIT = 0x01FF; // Sleep to standby transition cycles

FlashRegs.FACTIVEWAIT.bit.ACTIVEWAIT = 0x01FF; // Standby to active transition cycles

FlashRegs.FBANKWAIT.bit.RANDWAIT = 5; // Random access waitstates

FlashRegs.FBANKWAIT.bit.PAGEWAIT = 5; // Paged access waitstates

FlashRegs.FOTPWAIT.bit.OPTWAIT = 5; // Random access waitstates

FlashRegs.FOPT.bit.ENPIPE = 1; // Enable the flash pipeline

asm(" EDIS"); // Disable EALLOW protected register access

 

/*** Force a complete pipeline flush to ensure that the write to the last register

configured occurs before returning. Safest thing is to wait 8 full cycles. ***/

 

asm(" RPT #7 || NOP");

}

 

3.主程序开始调用函数之前,就可以了

memcpy( &secureRamFuncs_runstart,

&secureRamFuncs_loadstart,

&secureRamFuncs_loadend - &secureRamFuncs_loadstart);

InitFlash();