sd卡读写程序SDcardreadandwriteprogram.docx
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sd卡读写程序SDcardreadandwriteprogram
sd卡读写程序（SDcardreadandwriteprogram）
SDcardreadandwriteprogram
Objective:
TostudytheSDcard//operation
Design/software
1,usingSPIcommunication//SDcard
2,gotoSD//inorderto0-255atotalof256data,andthenreadbackLCD1602display
//hardwarerequirements:
S11ON//dialswitch
JumperJ18//allconnected
#include//dsPIC30F6014standardheaderfile
_FOSC（CSW_FSCM_O&FFXT_PLL4）;//4doublercrystaloscillator,Failsafeclockclosed
_FWDT（WDT_OFF）;//closethewatchdogtimer
_FBORPO（RPBOR_OFF&MCLR_EN）;//resetprohibitedMCLRresetenable.
_FGS（CODE_PROT_OFF）;//codeprotectionagainst#defineCSPORTGbits.RG9//SDcardselectionpindefinition#defineRSLATBbits.LATB4//definitionLCDcontrolbits（noteherecanonlyregisterwithLATB,youcannotdirectlyusethePORTBregister）
#defineRWLATBbits.LATB5
#defineeLATBbits.LATB6
Unsignedchar__attribute__（（address（0x900）））lcd[3]={0,0,0};
Void（spi_init）;//declarationsysteminitialfunction
Void（spi_low）;//thatproduceslowbaudrate（usingtheSDcardinitializationfunction）
Void（spi_high）;//thatproducehighbaudratefunction（SD
cardinitializationafteruse）
Unsignedchar（sd_reset）;//thattheSDcardinitializationfunction
UnsignedcharSD_SendComman（udnsignedcharCMDunsigned,long
ARG）;//writeSDcardcommandfunctionstatement
UnsignedcharSPI_WriteByte（unsignedcharVAL）;//writeabytefunctionstatement
UnsignedcharSPI_ReadByte（void）;//thatreceiveabytefunction
UnsignedcharSD_WriteSingleBlock（unsignedlongsector）;//thatsingleBLOCKdatawriteSDcardfunction
UnsignedcharSD_ReadSingleBlock（unsignedlongsector）;//readSDcarddatafunctionsingleBLOCKstatement
Void（lcd_display）;//stateresultsdisplayfunction
Void（delay）;//statedelayfunction（shownby）
//systeminitializationfunction
Voidspi_init（）
{
TRISG=0x00d0;//settheSDIoutput,Coutputportfortheother
TRISB=0X0000;//setfortheoutputportB
TRISD=0X0000;//setfortheoutputportD
SPI2CON=0x0278;//idlebusishigh,fosc/64
SPI2STAT=0x8000;//theendofsamplingtheoutputdataofinputdata,therisingedgeofdatatransmission
//writeabyteofdatafunction
Afterchangingthelevel//ontheneedtoinsertadelaytime,otherwisetheLCDreact.
Voidwrite（unsignedcharx）
{
PORTD=x;//PORTDporttosenddatatobedisplayed
Delay（）;
Rs=1;//thebytedata,ratherthancommand
Delay（）;
Rw=0;//theoperationforwriting,
Insteadofreading
Delay（）;
E=0;//lowenablesignal
（delay）;//keeptheenablesignalislowforaperiodoftime
Delay（）;
}
//********************LCDdisplaysettingsfunction
Afterchangingthelevel//ontheneedtoinsertadelaytime,otherwisetheLCDreact.
Voidlcd_enable（）
{
Delay（）;
Rs=0;//thebytedataforthecommand,ratherthanthedata
Delay（）;
Rw=0;//theoperationforwriting,insteadofreading
Delay（）;
E=0;//lowenablesignal
（delay）;//keeptheenablesignalislowforaperiodoftime
Delay（）;
}
//*********************LCDinitializationfunction
Voidlcd_init（）
{
PORTD=0X1;//display
Lcd_enable（）;
PORTD=0X38;//8bit2row5*7dotmatrix
Lcd_enable（）;
PORTD=0X0e;//display,cursor,flashing
Lcd_enable（）;
PORTD=0X06/;/thetextdoesnotmovethecursortotheright.
Lcd_enable（）;
PORTD=0X86;//timedisplay.
Lcd_enable（）;
//***********************LCDdisplayfunction
Voidlcd_display（）
{
UnsignedcharI,j;
Lcd_init（）;
For（i=0;i<3;//i++）atotalof3bytesofdata
{
Write（lcd[i]）;//look-uptablefordataandcalltowriteabyteofdatatotheLCDdisplayfunction
For（j=0;j<5;//j++）foraperiodoftime（mainlyinordertocontrolthedisplayspeed）
{delay（）;}
}
}
writeabyte
function
UnsignedcharSPI_WriteByte（unsignedcharVAL）
{
data
SPI2BUF=Val;//tobesenttothetransmittingregisterloading
While（IFS1bits.SPI2IF!
）;//waitforsent
IFS1bits.SPI2IF=0;//cleartosendcompleteflag
ReturnSPI2BUF;//readreceiveregister（eveninvaliddataisempty）
}
function
UnsignedcharSPI_ReadByte（void）
{
data
SPI2BUF=0xff;//sendregisterloadingdata,receivingtostart
While（IFS1bits.SPI2IF!
）;//waitforthecompletionofreceiving
IFS1bits.SPI2IF=0;//clearreceivecompleteflag
ReturnSPI2BUF;//readthereceiveddata
}
UnsignedcharSD_SendComman（udnsignedcharCMD,unsignedlongARG）
{
Unsignedcharr1;
Unsignedcharretry1=0;//thenumberofrepeatoperation
Cs=0;//thechipselectsignal
SPI_WriteByte（CMD0x40|）;//writecommandrespectively.
SPI_WriteByte（arg>>24）;//fourthbytedatasegment
SPI_WriteByte（arg>>16）;//thirdbytedatasegment
SPI_WriteByte（arg>>8）;//secondbytedatasegment
SPI_WriteByte（ARG）;//firstbytedatasegment
SPI_WriteByte（0x95）;//CRCchecksum
While（（R1=SPI_WriteByte（0xff））==0xff）//waitforaresponse
Ifbreak（retry1++>200）;//exittimeout
Cs=1;//earlychipselectsignal
ReturnR1;//returnstatus
}
//*******************SDinitializationfunction
Unsignedcharsd_reset（）
{
UnsignedcharI,tmp;
Unsignedcharretry;//repeat
Unsignedcharr1=0;
Retry=0;
Delay（）;
Delay（）;
Do
{
For（i=0;i<100;i++）SPI_WriteByte（0xff）;
R1=SD_SendCommand（0,0）;//idlecommand
Retry++;
If（retry>20）return1;//exittimeout
}while（R1!
=0x01）;//waitforthecommandtoreturnIDLE
Retry=0;
Cs=0;
Do
{
For（i=0;i<100;i++）SPI_WriteByte（0xff）;
R1=SD_SendCommand（1,0）;//Activecommand
Retry++;
If（retry>254）return1;//exittimeout}while（R1）;
For（i=0;i<100;i++）SPI_WriteByte（0xff）;
R1=SD_SendCommand（59,0）;//CRC
If（R1return1）;//returnisnotcorrect,exitinitialization
For（i=0;i<100;i++）SPI_WriteByte（0xff）;
R1=SD_SendCommand（16,512）;//setthesectorsize512
If（R1=0return1!
）;//returnisnotcorrect,exitinitialization
Return0;//returntonormal
}
writeasector
UnsignedcharSD_WriteSingleBlock（unsignedlongsector）{
Unsignedcharr1;
Unsignedinti;
Unsignedcharretry=0;
Do
{
For（i=0;i<100;i++）SPI_WriteByte（0xff）;
R1=SD_SendCommand（24,sector<<9）;//writecommand
Retry++;
If（retry>10）return1;//exittimeout
}while（R1==0x00）;
Cs=0;
SPI_WriteByte（0xff）;
SPI_WriteByte（0xff）;
SPI_WriteByte（0xff）;
SPI_WriteByte（0xff）;
SPI_WriteByte（0xff）;
SPI_WriteByte（0xff）;
SPI_WriteByte（0xFE）;//thestartsymbol
For（i=0;i<512;//i++）tosend512bytesofdata
If（i<255）SPI_WriteByte（I）;//send0--255
ElseSPI_WriteByte（512-i）;//send255--0
}
SPI_WriteByte（0x95）;
SPI_WriteByte（0x95）;//16-bitsCRC
R1=SPI_WriteByte（0xff）;//readaresponse
If（retry++>10）return1;
Timeout/exit
information
While（!
（（r1&0x0f）==5））;//waitfordatareceive
（while!
（SPI_WriteByte（0xff）））;//waitfortheinternalSDcardprogramming
Return0;
}
//******************SDcardreadingasector
UnsignedcharSD_ReadSingleBlock（unsignedlongsector）
{
UnsignedcharR1,temp;
Unsignedinti,j;
Unsignedcharretry=0;
Do
{
R1=SD_SendCommand（17,sector<<9）;//readcommandRetry++;
If（retry>10）return1;//exittimeout
}while（R1==0x00）;
Cs=0;
While（SPI_WriteByte（0xff）!
=0xFE）//waitforreceivingastartbyte
{
If（retry++>100）return1;//exittimeout
For（i=0;i<512;i++）//read512data
{
Temp=SPI_WriteByte（0xff）;//readthereceiveddata
Lcd[0]=（temp/100）+48;
Lcd[1]=（（temp%100）/10）+48;
Lcd[2]=（（temp%100）%10）+48;
（lcd_display）;//readdatasenttothedisplay
For（j=0;j<500;j++）{delay（）;}
}
SPI_WriteByte（0xff）;//pseudo16-bitsCRC
SPI_WriteByte（0xff）;
Cs=1;
}
Return0;
delayprocedures
Void（delay）/delayprocedure
{
Inti;//defineintegervariable
For（i=0x100;i--;）;//delay
}
Themainfunctionof
Intmain（void）
{
Unsignedcharloop,res;
Delay（）;
Delay（）;
Delay（）;
Loop=1;
Cs=1;
While（loop）
{
（spi_init）;//callsysteminitializationfunction
Res=（sd_reset）;//calltheSDcardinitializationfunction
If（RESbreak）;//SDcardinitializationisnormal,notnormal,
notoutoftheloopexecutesthereadandwriteoperations
SD_WriteSingleBlock
（1）;//callandwriteSDcardsingleBLOCKfunction,thesectoris1
If（RES）break;
SD_ReadSingleBlock
（1）;//callreadSDcardsingleBLOCK
function,thesectornumberis1
If（RES）break;
Loop=0;
While
（1）;
}
While
（1）;
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