[参考译文] TMS320F28P550SJ：MCAN 的整个消息 RAM 的大小

韦恩、您好！

可以，只要在应用程序之前设置访问位，就可以使用这些位置存储静态、全局和执行代码。

此致、

约瑟夫

韦恩、您好！

下面是一个实现示例。  下面是为 main.c 文件中的 MCANRAMACC 配置调用外部函数的 cinit 实现。

;// TI File $Revision: /main/2 $
;// Checkin $Date: December 7, 2011   18:25:05 $
;//###########################################################################
;//
;// FILE:  F2837x_CodeStartBranch._asm	
;//
;// TITLE: Branch for redirecting code execution after boot. 
;//
;// For these examples, code_start is the first code that is executed after
;// exiting the boot ROM code. 
;//
;// The codestart section in the linker cmd file is used to physically place
;// this code at the correct memory location.  This section should be placed 
;// at the location the BOOT ROM will re-direct the code to.  For example, 
;// for boot to FLASH this code will be located at 0x3f7ff6. 
;//
;// In addition, the example F2837x projects are setup such that the codegen
;// entry point is also set to the code_start label.  This is done by linker 
;// option -e in the project build options.  When the debugger loads the code,
;// it will automatically set the PC to the "entry point" address indicated by
;// the -e linker option.  In this case the debugger is simply assigning the PC, 
;// it is not the same as a full reset of the device. 
;// 
;// The compiler may warn that the entry point for the project is other then
;//  _c_init00.  _c_init00 is the C environment setup and is run before 
;// main() is entered. The code_start code will re-direct the execution 
;// to _c_init00 and thus there is no worry and this warning can be ignored. 
;// 
;//###########################################################################
;// $TI Release: F2837x C/C++ Header Files and Peripheral Examples V100 $
;// $Release Date: November 30, 2011 $
;//###########################################################################

***********************************************************************

WD_DISABLE	.set	1		;set to 1 to disable WD, else set to 0

    .ref _c_int00
    .global code_start

***********************************************************************
* Function: codestart section
*
* Description: Branch to code starting point
***********************************************************************

    .sect "codestart"
    .ref MCANRAM_Init

code_start:
	LCR MCANRAM_Init
    .if WD_DISABLE == 1
        LB wd_disable       ;Branch to watchdog disable code
    .else
        LB _c_int00         ;Branch to start of boot._asm in RTS library
    .endif

;end codestart section

***********************************************************************
* Function: wd_disable
*
* Description: Disables the watchdog timer
***********************************************************************
    .if WD_DISABLE == 1

    .text
wd_disable:
    SETC OBJMODE        ;Set OBJMODE for 28x object code
    EALLOW              ;Enable EALLOW protected register access
    MOVZ DP, #7029h>>6  ;Set data page for WDCR register
    MOV @7029h, #0068h  ;Set WDDIS bit in WDCR to disable WD
    EDIS                ;Disable EALLOW protected register access
    LB _c_int00         ;Branch to start of boot._asm in RTS library

    .endif

;end wd_disable

	.end
	
;//===========================================================================
;// End of file.
;//===========================================================================

这是 main.c 文件：

#include "stdint.h"
#include "sysctl.h"

#define MCANA_BASE 0x00058000U
#define MCANB_BASE 0x0005A000U
#define SYSCTL_O_MCANRAMACC       0x0090U

uint32_t Uninitialized_Array[10];                           // while halted at main, you will see this array as 0
uint32_t Initialized_Array[10] = {1,2,3,4,5,6,7,8,9,10};   // while halted at main, you will see this array initialized

uint32_t MCAN_isMemInitDone_local(uint32_t baseAddr);
void MCANRAM_Init(void);

int main(void)
{

    SysCtl_disableWatchdog();

    int i = 0;

    for(i=0;i<10;i++){
        Uninitialized_Array[i] = i*2;
        Initialized_Array[i] = i*3;
    }

    done();
}

void done()
{
    asm(" ESTOP0"); // check the values updated in both array location.
    for (;;);
}


uint32_t MCAN_isMemInitDone_local(uint32_t baseAddr)
{
    uint32_t memInit;
    uint32_t state;

    memInit = ((HWREG(baseAddr + MCAN_MCANSS_STAT) & MCAN_MCANSS_STAT_MEM_INIT_DONE_MASK) >> MCAN_MCANSS_STAT_MEM_INIT_DONE_SHIFT);
    if(1U == memInit)
    {
        state = (uint32_t) 1;
    }
    else
    {
        state = (uint32_t) 0;
    }
    return state;
}

void MCANRAM_Init(){

    if(HWREG(CPUSYS_BASE + SYSCTL_O_MCANRAMACC) != 0x3){
        // PCLKCR
        SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_MCANA);
        //MCAN RAM Check
        //
        // Reset the peripheral.
        //
        SysCtl_resetPeripheral(SYSCTL_PERIPH_RES_MCANA);
        //Wait till Memory initialization is done
        while (MCAN_isMemInitDone_local(MCANA_BASE) == 0)
            ;

        SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_MCANB);
        //MCAN RAM Check
        //
        // Reset the peripheral.
        //
        SysCtl_resetPeripheral(SYSCTL_PERIPH_RES_MCANB);
        //Wait till Memory initialization is done
        while (MCAN_isMemInitDone_local(MCANB_BASE) == 0)
            ;

        EALLOW;
        HWREG(CPUSYS_BASE + SYSCTL_O_MCANRAMACC) |= 0x3U;
        EDIS;
    }
    // MCANRAMACC
}

...这里是将 MCAN 消息 RAM 用于.bss 和.data 段的链接器命令。

-stack 0x100
-heap 0x100
--retain MCANRAM_Init

MEMORY
{
PAGE 0 :
   RAMLS012           	: origin = 0x00008000, length = 0x0001800
   RESET           	: origin = 0x003FFFC0, length = 0x00000002
   BOOT_RSVD_SYSBIOS: origin = 0x00000780, length = 0x00000080
   MCANARAM			: origin = 0x00058000, length = 0x800
   MCANBRAM			: origin = 0x0005A000, length = 0x800

}



SECTIONS
{
   .text            : > RAMLS012
   .cinit           : > RAMLS012
   .reset           : > RESET,     					TYPE = DSECT /* not used, */
   codestart		: > RAMLS012
   .stack           : > RAMLS012
   .bss:.cio        : > RAMLS012
   .sysmem          : > RAMLS012
   .const			: > RAMLS012
   .rodata 			: > RAMLS012

   .data            : >> MCANARAM | MCANBRAM
   .bss             : >> MCANARAM | MCANBRAM
}

/*
//==============
=============================================================
// End of file.
//===========================================================================

此致、

约瑟夫