Nios II中Flash的使用|Nios II

Nios II中Flash的使用

2012-06-02

在嵌入式系统中，Flash是最常用组件之一。许多使用过flash的朋友都了解，Flash的特点是“读来容易写来难”。通常，可以直接读出Flash的内容；但如果要写入数据，就要发送一长串命令，比如像：555 ，AA，2AA，55，555，A0 ，PA，PD就表示对PA地址写入数据PD,实际情况还要复杂一点，因为通常还要包含许多查询操作。

哎呀，这真是好繁琐呀，有没有省力的方法呢？现在好了，NiosII的开发环境提供了对符合CFI标准的Flash的支持，使用几个简单的函数，就可以操作Flash,真是方便了许多。

在这里，我粗略得介绍一下nios 中flash的使用；更加详细的帮助信息请您参考Altera公司提供的文档。如果本文能对您有一点点帮助，我都会感到非常高兴。

1 准备工作：

在使用Flash之前，有几个准备工作要做：

开发板上至少要有一片符合CFI标准的Flash。

设计好对应目标板的Flash编程器（Flash Programmer）。

下面我以本站设计的开发板ezNiosDKC6B为目标板，来介绍如何使用Flash，你可以举一反三，在自己的系统中使用Flash.

2 为SOPC系统中添加Flash接口：

双击在Memory中的Flash Memory(Common Flash Interface)，即可为系统添加Flash接口。

对于ezNiosDK的用户，Address Width可以选择 20 Bits,Data Width 可以选择 16 Bits,这样总的容量是2M Bytes

Timing选项卡中，可以如下添写：

完成后，选择Finish，即可为系统添加Flash接口。

增加三态总线桥。Flash 接口必须通过三态总线桥接到实际的芯片上。双击Bridges下的Avalon Tri-State Bridge,请按照下图设置，为系统增加三态总线桥。

为Flash接口分配引脚。

注意，如果Data Width是16Bits，那么tri_state_bridge_0_address[0]不必接到Flash上，tri_state_bridge_0_address[1]对应Flash的A[0],tri_state_bridge_0_address[2]对应Flash的A[1]，以此类推。

3 在Nios IDE中使用Flash编程器：

3-1 配置Component/Kit Library Search Path。

目的是在系统中增加本站设计的Flash编程器目录，请把光盘CD1上的/Example/ezNiosC6 拷贝到您的电脑的硬盘上。比如，我把他放在h:/DB2005/project/niosDK/CD/CD1/Example/中，然后在Altera SOPC Builder中，选择File -> SOPC Builder Setup，增加如下搜索路径：+h:/DB2005/project/niosDK/CD/CD1/Example/ezNiosC6

ezNiosC3的用户如下操作：请把光盘CD1上的/Example/ezNiosC3 拷贝到您的电脑的硬盘上。比如，我把他放在h:/DB2005/project/niosDK/CD/CD1/Example/中，然后在Altera SOPC Builder中，选择File -> SOPC Builder Setup，增加如下搜索路径：+h:/DB2005/project/niosDK/CD/CD1/Example/ezNiosC3

并顺便检察Modelsim Directory是否正确：比如，我的是 g:/w2k/eda/fpga/altera/modeltech_6.0/win32

然后，你需要关闭Altera SOPC Builder,然后再重新通过QuartusII的Tools ->SOPC Builder来开启SOPC Builder，这样上述修改才能生效。

常见错误：有许多朋友往往在设置路径的时候，犯与下图类似的错误。错误在于第一个路径前面是不需要 + 号的！要去掉第一个路径前面的 + 号

3-2:使用Flash编程器。

我使用项目：ezC6Be_StdF50_zip_filesystem_0（在CD1ExampleezNiosC6BezC6Be_StdF50softwareezC6Be_StdF50_zip_filesystem_0下，请使用Nios IDE中的File-Import来导入这个项目），来说明如何使用Flash编程器。

首先为系统上电，并连接好下载电缆。

选择Tools -> Flash Programmer,启动 Flash 编程器

选择New,可以看到增加了一个名为 ezC6Be_StdF50_zip_filesystem_0 programmer的flash 编程器

选择Program software project into flash memory，然后选择Apply,在选择Program Flash，就启动了Flash 编程器！如果顺利的话，可以看到如下的提示:

如果看到如上提示，OK,小功告成，我们已经可以正常使用Flash编程器啦！

下面我来介绍如何在程序中引用Flash。

使用NiosII提供的系统函数，可以方便得使用Flash,免除了通常操作Flash 的繁琐，这对用户来说，真是方便多了。

Altera 提供了两种类型的函数，提供给客户：Simple Flash Access（简单的Flash访问），以及Fine-Grained Flash Access（细粒度Flash访问）。

一般情况下，我还是推荐使用Fine-Grained Flash Access（细粒度Flash访问）函数，比Simple Flash Access也复杂不了多少，但可以避免通常的跨块擦除问题。因为Flash是按照Block组织起来的，通常一次擦除一整个块。如果写Flash的地址于Flash块的组织结构不吻合，比如跨越了Flash块的边缘，那么可能会擦除掉其余的数据。比如，即使要写入1Byte,也要擦除掉4Kbyte,也许这4Kbyte里面还有许多有用的数据，就会被抹掉。

我们下面介绍几个常用的函数，关于更详细的内容，请参考Altera提供的文档。

首先介绍第一步：打开Flash，就像c程序打开硬盘中的数据文件一样，使用之前要打开Flash.我们使用alt_flash_open_dev()打开Flash,它返回一个句柄。比如，下面是使用这个函数的片断：

alt_flash_fd* fd;

fd = alt_flash_open_dev(EXT_FLASH_NAME);

其中，EXT_FLASH_NAME是预先定义的Flash的名字（#defineEXT_FLASH_NAME"/dev/ext_flash"），接下来的操作，都是通过该句柄：fd,来访问Flash的。

读出Flash使用函数：alt_read_flash,原型如下：

int alt_read_flash( alt_flash_fd* fd,

int offset,

void* dest_addr,

int length )

使用完了，也别忘记关闭该Flash,就象读写完硬盘中的数据文件后要关闭一样。其原型如下：

void alt_flash_close_dev(alt_flash_fd* fd )

Fine-Grained Flash Access机制提供了如下几个函数：alt_get_flash_info(), alt_erase_flash_block(), alt_write_flash_block()。

alt_get_flash_info()可以提取Flash的信息，比如包含几个区域，每个区域有几个块，每个块的大小等等。它的原型如下：

int alt_get_flash_info( alt_flash_fd* fd,flash_region** info,int* number_of_regions)

比如，如下就是一个调用该函数的程序片断：

intret_code = 0;

intnumber_of_regions=0;

flash_region* regions;

ret_code = alt_get_flash_info(fd, &regions, &number_of_regions

这里涉及到一个结构：flash_region,原型如下：

typedef struct flash_region

{int offset;/* Offset of this region from start of the flash */

int region_size;/* Size of this erase region */

int number_of_blocks;/* Number of blocks in this region */

int block_size;/* Size of each block in this erase region */

}flash_region;

擦除一个块使用函数：alt_flash_fd,函数原型如下：

int alt_erase_flash_block( alt_flash_fd* fd,int offset,int length)

写入一个块使用函数：alt_write_flash_block,函数原型如下：

int alt_write_flash_block( alt_flash_fd* fd,

int block_offset,

int data_offset,

const void *data,

int length)

罗罗嗦嗦说了这么多，下面我们来看一个实际的范例；这个范例是我使用来测试flash的，相信大家可以从中获益良多。

#include

#include"alt_types.h"

#include"sys/alt_flash.h"

#include"sys/alt_flash_dev.h"

#defineNUM_BYTES_TO_WRITE 512

//#define NUM_BYTES_TO_WRITE 64

* test_programming() is called by main to test a range of flash by

* writing incrementing patterns, then reading them back and comparing

* the result

* The start of the range to be tested is defined by test_offset, and

* the size of the range to be tested is defined by NUM_BYTES_TO_WRITE

inttest_programming( alt_flash_fd* fd,inttest_offset)

{

inti,j;

alt_u8 data_written[NUM_BYTES_TO_WRITE];

alt_u8 data_read[NUM_BYTES_TO_WRITE];

intret_code = 0;

inttest_length =sizeof(data_written);

* 30 iterations takes about 60 seconds

for(j=0;j<7;j++)

{

for(i=0;i

data_written[i] = j*0x15;

for(i=sizeof(data_written)/2;i

data_written[i] = (j*0x15)+1;　

ret_code = alt_write_flash(fd, test_offset, data_written, test_length);

if(!ret_code)

{

ret_code = alt_read_flash(fd, test_offset, data_read, test_length);

if(!ret_code)

{

if(memcmp(data_written, data_read, test_length))

{

printf(" ERROR: compare failed sector offset %#x iteration%#x ",

test_offset, j);

returnret_code;

}

printf("*");

if(ret_code)

{

printf(" ERROR: function alt_write_flash failed. ret_code %d ",

ret_code);

returnret_code;

}

returnret_code;

}

inttest_flash_erase( alt_flash_fd* fd)

{

intret_code = 0;

intnumber_of_regions=0;

flash_region* regions;

inti,j,k;

inttest_offset;

inttest_length;

alt_u8 read_data[200] ;

ret_code = alt_get_flash_info(fd, &regions, &number_of_regions);

if(ret_code)

{

printf(" ERROR: function alt_get_flash_info failed. ret_code %d ",

ret_code);

}

* If this is the development board check the number of regions etc.

printf(" This is AMD29LV160DB ");

printf("Flash name %s ",fd->name);　

printf("This flash has %d erase regions ", number_of_regions);

for(i=0;i

{

printf("Start 0x%8x End 0x%8x Number of Blocks %3d Block Size 0x%8x ",

(regions+i)->offset,

(regions+i)->region_size+(regions+i)->offset,

(regions+i)->number_of_blocks,

(regions+i)->block_size);

}　

for(j=0;j

{

for(i=0;i<((regions+j)->number_of_blocks);i++)

{ test_offset = (regions+j)->offset + i*(regions+j)->block_size;

test_length = (regions+j)->block_size;

printf(" ---Testing flash block erase...@ 0x%8x length= 0x%8x

",test_offset,test_length);

ret_code = alt_erase_flash_block(fd, (regions+j)->offset + i*(regions+j)-

>block_size, (regions+j)->block_size);

if(ret_code)

{

printf(" ERROR: function alt_erase_flash_block failed. ret_code %d ",

ret_code);

break;

}

else

{

ret_code = alt_read_flash(fd, test_offset, read_data, 100);

for(k=0;k<100;k++)

{

if(read_data[k] != 0xff)

{

printf(" ERROR: erase compare failed. %d %#x ", k, read_data[k]);

break;

}

}//@for(i=1

}//@for(j=1)

printf(" passed. ");

returnret_code;

}

inttest_flash_write( alt_flash_fd* fd)

{

intret_code = 0;

intnumber_of_regions=0;

flash_region* regions;

inti,j,k;

inttest_offset;

inttest_length;

alt_u8 read_data[200] ;

alt_u8 write_data[200];

ret_code = alt_get_flash_info(fd, &regions, &number_of_regions);

if(ret_code)

{

printf(" ERROR: function alt_get_flash_info failed. ret_code %d ",

ret_code);

}

* If this is the development board check the number of regions etc.

printf(" This is AMD29LV160DB ");

printf("Flash name %s ",fd->name);　

printf("This flash has %d erase regions ", number_of_regions);

for(i=0;i

{

printf("Start 0x%8x End 0x%8x Number of Blocks %3d Block Size 0x%8x ",

(regions+i)->offset,

(regions+i)->region_size+(regions+i)->offset,

(regions+i)->number_of_blocks,

(regions+i)->block_size);

}　

for(j=0;j

{

for(i=0;i<((regions+j)->number_of_blocks);i++)

{ test_offset = (regions+j)->offset + i*(regions+j)->block_size;

test_length = (regions+j)->block_size;

printf(" ---Testing flash block erase...@ 0x%8x length= 0x%8x

",test_offset,test_length);

ret_code = alt_erase_flash_block(fd, (regions+j)->offset + i*(regions+j)-

>block_size, (regions+j)->block_size);

if(ret_code)

{

printf(" ERROR: function alt_erase_flash_block failed. ret_code %d ",

ret_code);

break;

}

else

{

ret_code = alt_read_flash(fd, test_offset, read_data, 100);

for(k=0;k<100;k++)

{

if(read_data[k] != 0xff)

{

printf(" ERROR: erase compare failed. %d %#x ", k, read_data[k]);

break;

}

}//@for (k=0)　

printf(" -----------Now Testing flash block write...@ 0x%8x ",test_offset);　

for(k=0;k<100;k++)

write_data[k] = k;　

ret_code = alt_write_flash_block( fd, (regions+j)->offset + i*(regions+j)-

>block_size,

test_offset + i, write_data, 100);

if(ret_code)

{

printf(" ERROR: function aXlt_write_flash_block failed. ret_code %d ",

ret_code);

break;

}

else

{ ret_code = alt_read_flash(fd, test_offset + i, read_data, 100);

for(k=0;k<100;k++)

{

if(read_data[k] != write_data[k])

{printf(" ERROR: compare failed, expected %#x read %#x ",write_data[i],

read_data[i]);

break;

}

}//@ else　

}

}//@for(i=1

}//@for(j=1)

printf(" passed. ");

returnret_code;

}

* test_get_info() is called by main to test that the regions, sector

* size, block size and number of blocks can be correctly read from

* the flash

inttest_get_info( alt_flash_fd* fd)

{

intret_code = 0;

intnumber_of_regions=0;

flash_region* regions;

inti;

ret_code = alt_get_flash_info(fd, &regions, &number_of_regions);

if(ret_code)

{

printf(" ERROR: function alt_get_flash_info failed. ret_code %d ",

ret_code);

}

* If this is the development board check the number of regions etc.

if(0)

{

}

else

{

printf(" This is not the standard reference design ");

printf("Flash name %s ",fd->name);

printf("This flash has %d erase regions ", number_of_regions);

for(i=0;i

{

printf("Start 0x%8x End 0x%8x Number of Blocks %3d Block Size 0x%8x ",

(regions+i)->offset,

(regions+i)->region_size+(regions+i)->offset,

(regions+i)->number_of_blocks,

(regions+i)->block_size);

}

returnret_code;

}

* Run various tests on a small section of the system flash.

intmain (void)

{

intret_code;

inttest_offset;

alt_flash_fd* fd;

alt_u8 write_data[100];

alt_u8 read_data[100];

inti,j;　

fd = alt_flash_open_dev(EXT_FLASH_NAME);　

if(fd)

{

printf(" <----> Running Flash Tests <----> ");

printf("This will take approximately 1 minute ");　

printf("-Testing flash info retrieval...");

ret_code = test_get_info(fd);

if(ret_code)

{

printf(" ERROR: function test_get_info failed. ret_code %d ",

ret_code);

gotofinished;

}

printf(" passed. ");　

printf("-Testing flash block erase,write... ");

ret_code = test_flash_write(fd);

if(ret_code)

{

printf(" ERROR: test_flash_erase failed. ret_code %d ",

ret_code);

gotofinished;

}

printf(" passed. ");　

printf("-Testing flash write... ");　

test_offset = 0x0;

printf(" test_offset=0x%8x ",test_offset);

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

printf(" passed. ");　

test_offset = 0x4000;

printf(" test_offset=0x%8x ",test_offset);

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

printf(" passed. ");　

test_offset = 0x6000;

printf(" test_offset=0x%8x ",test_offset);

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

printf(" passed. ");　

test_offset = 0x8000;

printf(" test_offset=0x%8x ",test_offset);

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

printf(" passed. ");　

for(j=1;j<=31;j++)

{test_offset = 0x10000*j;

printf(" test_offset=0x%8x ",test_offset);

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

}

printf(" passed. ");　

printf(" 0x10ff00: ");

test_offset = 0x10ff00;

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

printf(" passed. ");　

printf(" 0x100100: ");

test_offset = 0x100100;

ret_code = test_programming(fd, test_offset);

if(ret_code)

gotofinished;

printf(" passed. ");

printf("-Testing flash block erase... ");

ret_code = test_flash_erase(fd);

if(ret_code)

{

printf(" ERROR: test_flash_erase failed. ret_code %d ",

ret_code);

gotofinished;

}

printf(" passed. ");

test_offset = 0x10000;

printf(" ---Testing flash block write...@ 0x%8x ",test_offset);　

for(i=0;i<100;i++)

write_data[i] = i;　

ret_code = alt_write_flash_block( fd, 0x10000,

test_offset, write_data,

100);

if(ret_code)

{

printf(" ERROR: function alt_write_flash_block failed. ret_code %d ",

ret_code);

gotofinished;

}

else

{

ret_code = alt_read_flash(fd, test_offset, read_data, 100);

for(i=0;i<100;i++)

{

if(read_data[i] != write_data[i])

{

printf(" ERROR: compare failed, expected %#x read %#x ",

write_data[i], read_data[i]);

gotofinished;

}

printf(" passed. ");　

test_offset = 0x10010;

printf("-Testing unaligned writes.....");

alt_erase_flash_block(fd, 0x10000, 0x100000);　

ret_code = alt_write_flash_block( fd, 0x10000,

test_offset, write_data,100);　

if(ret_code)

{

printf(" ERROR: function alt_write_flash_block failed. ret_code %d ",

ret_code);

gotofinished;

}

else

{

ret_code = alt_read_flash(fd, test_offset, read_data, 100);

for(i=0;i<100;i++)

{

if(read_data[i] != write_data[i])

{

printf(" ERROR: compare failed, expected %#x read %#x ",

write_data[i], read_data[i]);

gotofinished;

}

printf(" passed. ");　

printf("-Testing flash block erase... ");

ret_code = test_flash_erase(fd);

if(ret_code)

{

printf(" ERROR: test_flash_erase failed. ret_code %d ",

ret_code);

gotofinished;

}

printf(" passed. ");　

printf("All Tests Passed! ");

}

else

{

printf("Can't open the flash device ");

}

finished:

alt_flash_close_dev(fd);

printf("Exiting Flash Tests ");　

return0;

}

可能会用到的工具/仪表