|
|
基于51單片機(jī)和Proteus仿真的SD卡讀卡器，包含C語(yǔ)言源程序及Proteus仿真電路圖，親測(cè)完全可用，部分代碼如下，全部代碼見(jiàn)附件
#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 //回車
//定義SD卡需要的4根信號(hào)線
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];
//定義512字節(jié)緩沖區(qū)，注意需要使用 xdata關(guān)鍵字
//===========================================================
//寫(xiě)一字節(jié)到SD卡,模擬SPI總線方式
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;
}
//===========================================================
//從SD卡讀一字節(jié),模擬SPI總線方式
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;
}
//============================================================
//檢測(cè)SD卡的響應(yīng)
unsigned char SdResponse()
{
unsigned char i=0,response;
while(i<=8)
{
response = SdRead();
if(response==0x00)
break;
if(response==0x01)
break;
i++;
}
return response;
}
//================================================================
//發(fā)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卡指定地址寫(xiě)數(shù)據(jù),一次最多512字節(jié)
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); //兩字節(jié)CRC校驗(yàn), 為0XFFFF 表示不考慮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;
}
//=======================================================================
//從SD卡指定地址讀取數(shù)據(jù),一次最多512字節(jié)
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;//工作與方式1不允許接受
TMOD=0x20;//定時(shí)器1工作與方式2自動(dòng)重裝模式
TH1=RELOAD;
TR1=1;
TI=0;
}
//通過(guò)串口發(fā)送一個(gè)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);//寫(xiě)入字符串，然后讀出進(jìn)行檢驗(yàn)
SdReadBlock(DATA,0x000000,15);
Sen_String(DATA); //發(fā)出數(shù)據(jù)
while(1)
{
}
}
全部資料51hei下載地址：
基于51單片機(jī)和Proteus仿真的SD卡讀卡器.zip
(215.48 KB, 下載次數(shù): 186)
2019-5-9 16:22 上傳
點(diǎn)擊文件名下載附件
|
評(píng)分
-
查看全部評(píng)分
|
