单片机SD卡读卡器仿真+源程序+电路原理图

ID:137190 · 发表于 2016-8-31 23:05

分享一个51单片机做的SD卡读卡器仿真带源程序，一个简单的MMC卡存储器应用。下面是电路原理图：

可以看到虚拟窗口的结果出来了.

单片机SD卡读卡器设计的源程序如下：

#include <AT89X52.H>
#define F_OSC 11059200//晶振平率Hz
#define F_BAUD 9600
#define RELOAD 256-F_OSC/12/32/F_BAUD
#define CR 0x0D //回车
//定义SD卡需要的4根信号线
sbit SD_CLK = P1^4;
sbit SD_DI = P1^6;
sbit SD_DO = P1^5;
sbit SD_CS = P1^7;
unsigned char xdata DATA[512];
//定义512字节缓冲区，注意需要使用 xdata关键字
//===========================================================
//写一字节到SD卡,模拟SPI总线方式
void SdWrite(unsigned char n)
{
unsigned char i;
for(i=8;i;i--)
{
SD_CLK=0;
SD_DI=(n&0x80);
n<<=1;
SD_CLK=1;
}
SD_DI=1;
}
//===========================================================
//从SD卡读一字节,模拟SPI总线方式
unsigned char SdRead()
{
unsigned char n,i;
for(i=8;i;i--)
{
SD_CLK=0;
SD_CLK=1;
n<<=1;
if(SD_DO) n|=1;
}
return n;
}
//============================================================
//检测SD卡的响应
unsigned char SdResponse()
{
unsigned char i=0,response;
while(i<=8)
{
response = SdRead();
if(response==0x00)
break;
if(response==0x01)
break;
i++;
}
return response;
}
//================================================================
//发命令到SD卡
void SdCommand(unsigned char command, unsigned long argument, unsigned char CRC)
{
SdWrite(command|0x40);
SdWrite(((unsigned char *)&argument)[0]);
SdWrite(((unsigned char *)&argument)[1]);
SdWrite(((unsigned char *)&argument)[2]);
SdWrite(((unsigned char *)&argument)[3]);
SdWrite(CRC);
}
//================================================================
//初始化SD卡
unsigned char SdInit(void)
{
int delay=0, trials=0;
unsigned char i;
unsigned char response=0x01;
SD_CS=1;
for(i=0;i<=9;i++)
SdWrite(0xff);
SD_CS=0;
//Send Command 0 to put MMC in SPI mode
SdCommand(0x00,0,0x95);
response=SdResponse();
if(response!=0x01)
{
return 0;
}
while(response==0x01)
{
SD_CS=1;
SdWrite(0xff);
SD_CS=0;
SdCommand(0x01,0x00ffc000,0xff);
response=SdResponse();
}
SD_CS=1;
SdWrite(0xff);
return 1;
}
//================================================================
//往SD卡指定地址写数据,一次最多512字节
unsigned char SdWriteBlock(unsigned char *Block, unsigned long address,int len)
{
unsigned int count;
unsigned char dataResp;
//Block size is 512 bytes exactly
//First Lower SS
SD_CS=0;
//Then send write command
SdCommand(0x18,address,0xff);
if(SdResponse()==00)
{
SdWrite(0xff);
SdWrite(0xff);
SdWrite(0xff);
//command was a success - now send data
//start with DATA TOKEN = 0xFE
SdWrite(0xfe);
//now send data
for(count=0;count<len;count++) SdWrite(*Block++);
for(;count<512;count++) SdWrite(0);
//data block sent - now send checksum
SdWrite(0xff); //两字节CRC校验, 为0XFFFF 表示不考虑CRC
SdWrite(0xff);
//Now read in the DATA RESPONSE token
dataResp=SdRead();
//Following the DATA RESPONSE token
//are a number of BUSY bytes
//a zero byte indicates the MMC is busy
while(SdRead()==0);
dataResp=dataResp&0x0f; //mask the high byte of the DATA RESPONSE token
SD_CS=1;
SdWrite(0xff);
if(dataResp==0x0b)
{
//printf("DATA WAS NOT ACCEPTED BY CARD -- CRC ERROR\n");
return 0;
}
if(dataResp==0x05)
return 1;
//printf("Invalid data Response token.\n");
return 0;
}
//printf("Command 0x18 (Write) was not received by the MMC.\n");
return 0;
}
//=======================================================================
//从SD卡指定地址读取数据,一次最多512字节
unsigned char SdReadBlock(unsigned char *Block, unsigned long address,int len)
{
unsigned int count;
//Block size is 512 bytes exactly
//First Lower SS
//printf("MMC_read_block\n");
SD_CS=0;
//Then send write command
SdCommand(0x11,address,0xff);
if(SdResponse()==00)
{
//command was a success - now send data
//start with DATA TOKEN = 0xFE
while(SdRead()!=0xfe);
for(count=0;count<len;count++) *Block++=SdRead();
for(;count<512;count++) SdRead();
//data block sent - now send checksum
SdRead();
SdRead();
//Now read in the DATA RESPONSE token
SD_CS=1;
SdRead();
return 1;
}
//printf("Command 0x11 (Read) was not received by the MMC.\n");
return 0;
}
/*******************************************
串口初始化
*******************************************/
void UART()
{
SCON=0x40;//工作与方式1不允许接受
TMOD=0x20;//定时器1工作与方式2自动重装模式
TH1=RELOAD;
TR1=1;
TI=0;
}
//通过串口发送一个字符串
void Sen_String(unsigned char *string)
{
while(*string!='\0')
{
if(*string=='\n')
{
SBUF=CR;
}
else
{
SBUF=*string;
}
while(TI==0);
TI=0;
string++;
}
}
void main()
{
UART();
while(!SdInit()); //等待SD卡初始化完成
SdWriteBlock("THIS IS A TEST!",0x000000,15);//写入字符串，然后读出进行检验
SdReadBlock(DATA,0x000000,15);
Sen_String(DATA); //发出数据
while(1)
{
}
}

复制代码

单片机SD卡读卡器仿真工程文件及其他完整资料下载：
http://www.51hei.com/bbs/dpj-54940-1.html

ID:138115 · 发表于 2016-9-1 00:07

非常赞

ID:183431 · 发表于 2017-3-25 22:46

非常感谢，刚好像自己做个sd卡读卡器呢

ID:99130 · 发表于 2017-4-25 22:34

第一个图右边的是什么东西接单片机TXD那个

ID:185661 · 发表于 2017-4-27 08:50

一直在寻找sd卡资料，没想到在这里找到了，感谢楼主分享

ID:235656 · 发表于 2018-1-2 22:30

51做的读卡器读写速度怎么样？

ID:263813 · 发表于 2018-1-3 16:56

找资料不易，收藏

ID:268118 · 发表于 2018-1-12 02:31

感謝樓主的分享。

ID:265553 · 发表于 2018-1-14 07:38

正好需要下载了，感谢

ID:281852 · 发表于 2018-2-2 23:15

mark下，最近会用到

ID:79874 · 发表于 2018-7-1 05:45

非常感谢分享学习

ID:375092 · 发表于 2019-3-31 20:50

点赞，为你鼓掌

ID:155507 · 发表于 2019-7-7 12:01

感謝樓主的分享。

ID:400715 · 发表于 2020-4-17 14:53

太有用了

ID:957712 · 发表于 2021-8-17 19:09

正好可以学习，谢谢楼主的分享。

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