SD模块测试C程序文档格式.docx

SD模块测试C程序文档格式.docx

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//Do

voidDelay5us（）

{

unsignedchara=0;

for（a=0;

a<

40;

a++）

;

}

//********************************************

voidSD_2Byte_Write（unsignedintIOData）

unsignedcharBitCounter;

for（BitCounter=0;

BitCounter<

16;

BitCounter++）

{

sd_clk=0;

//CLKLow

if（IOData&

0x8000）//IftheMSBofIODatais1,thenDo=1,elseDo=0.

sd_dao=1;

//DoHigh

else

sd_dao=0;

//DoLow

sd_clk=1;

//CLKHigh

Delay5us（）;

IOData=IOData<

<

1;

//BecausetheMSBistransmittedfirstly,shifttonextlowerbit.

}

voidSD_Write（unsignedintIOData）

IOData=IOData<

8;

unsignedintSD_2Byte_Read（）

unsignedintBuffer;

Buffer=0;

Buffer=Buffer<

//BecausetheLSBwillbedamaged,wecannotputthislineundernextline.

if（sd_dai）

Buffer++;

//IfSPI_Din=1thentheLSB_of_Buffer=1.

returnBuffer;

unsignedintSD_Read（）

Buffer=0xffff;

unsignedintSD_CMD_Write（unsignedintCMDIndex,unsignedlongCMDArg,unsignedintResType,unsignedintCSLowRSV）//ResType:

ResponseType,send1forR1;

send2forR1b;

send3forR2.

{//Thereare7stepsneedtodo.（markedby[1]-[7]）

unsignedinttemp,Response,Response2,CRC,MaximumTimes;

Response2=0;

MaximumTimes=10;

CRC=0x0095;

//0x0095isonlyvalidforCMD0

if（CMDIndex!

=0）CRC=0x00ff;

sd_cse=0;

//[1]CSLow

SD_2Byte_Write（（（CMDIndex|0x0040）<

8）+（CMDArg>

>

24））;

//[2]TransmitCommand_Index&

1stByteofCommand_Argument.

SD_2Byte_Write（（CMDArg&

0x00ffff00）>

8）;

//[2]2nd&

3rdByteofCommand_Argument

SD_2Byte_Write（（（CMDArg&

0x000000ff）<

8）+CRC）;

//[2]4thByteofCommand_Argument&

CRConlyforCMD0

sd_dao=1;

//[3]DoHigh

//[3]RestoreDotoHighLevel

for（temp=0;

temp<

temp++）//[4]Provide8extraclockafterCMD

switch（ResType）//[5]waitresponse

case1:

//R1

{

do

Response=SD_Read（）;

while（Response==0xffff）;

break;

}

case2:

//R1b

//ReadR1firstly

Response2=SD_Read（）-0xff00;

while（Response2!

=0）;

//WaituntiltheBusy_Signal_Tokenisnon-zero

case3:

Response=SD_2Byte_Read（）;

break;

//R2

if（CSLowRSV==0）sd_cse=1;

//[6]CSHigh（iftheCMDhasdatablockresponseCSshouldbekeptlow）

temp++）//[7]Provide8extraclockaftercardresponse

returnResponse;

unsignedintSD_Reset_Card（）

unsignedinttemp,MaximumTimes;

80;

temp++）//Send74+Clocks

returnSD_CMD_Write（0x0000,0x00000000,1,0）;

//SendCMD0

unsignedintSD_Initiate_Card（）//Pollingthecardafterreset

unsignedinttemp,Response,MaximumTimes;

MaximumTimes=50;

for（temp=0;

MaximumTimes;

temp++）

Response=SD_CMD_Write（0x0037,0x00000000,1,0）;

//SendCMD55

Response=SD_CMD_Write（0x0029,0x00000000,1,0）;

//SendACMD41

if（Response==0xff00）

temp=MaximumTimes;

unsignedintSD_Get_CardInfo（）//ReadCSDregister

Response=SD_CMD_Write（9,0x00000000,1,1）;

//SendCMD9

temp++）//Provide8clocktoromovethefirstbyteofdataresponse（0x00fe）

temp++）ReadBuffer[temp]=SD_2Byte_Read（）;

//GettheCSDdata

temp++）//Provide16clocktoremovethelast2bytesofdataresponse（CRC）

sd_cse=1;

//CS_High（）

temp++）//Provide8extraclockafterdataresponse

BlockNR=（（ReadBuffer[3]<

2）&

0x0fff）+（（ReadBuffer[4]>

14）&

0x0003）+1;

//CalcuateMULT

BlockNR=BlockNR*（0x0002<

（（（ReadBuffer[4]<

1）&

0x0007）+（（ReadBuffer[5]>

15）&

0x0001）+1））;

//CalcuateBlock_Number

unsignedintSD_Overall_Initiation（）

unsignedintResponse,Response_2;

Response=0x0000;

Response_2=0xff00;

//[1]DoHigh

//[1]DomustbeHighwhenthereisnotransmition

do

Response=SD_Reset_Card（）;

//[2]SendCMD0

while（Response!

=0xff01）;

if（Response!

=0xff01）Response_2+=8;

//Response=SD_CMD_Write（8,0x00000000,1,0）;

//SendCMD8

Response=SD_Initiate_Card（）;

//[3]SendCMD55+ACMD41

if（Response==0xff00）

;

else

{

Response_2+=4;

}

Response=SD_Get_CardInfo（）;

//[4]ReadCSD

=0xff00）;

if（Response==0xff01）Response_2+=2;

returnResponse_2;

//0000|0000||0000|0000Response_2

//|||_CSDFail

//||__CMD55+ACMD41Fail

//|___CMD0Fail

unsignedintSD_Get_CardID（）//ReadCIDregister

Response=SD_CMD_Write（10,0x00000000,1,1）;

//GettheCIDdata

unsignedintRead_Single_Block（unsignedlongintBlockAddress）

if（BlockAddress>

BlockNR）return0xff20;

//whetherBlockAddressoutofrange?

Response=SD_CMD_Write（17,BlockAddress,1,1）;

//SendCMD17

while（SD_Read（）!

=0xfffe）{;

//这里为了使只有512byte的单片机能够读写SD卡，特意节省了RAM的使用量，每次读写只有两个重复的128byte

//如果您使用的单片机拥有1K以上的RAM请将"

%128"

去掉

256;

temp++）ReadBuffer[temp%128]=SD_2Byte_Read（）;

//Getthereadeddata

unsignedintWrite_Single_Block（unsignedlongintBlockAddress）

Response=SD_CMD_Write（24,BlockAddress,1,1）;

//SendCMD24

temp++）//Provide8extraclockafterCMDresponse

SD_Write（0x00fe）;

//SendStartBlockToken

去掉

temp++）SD_2Byte_Write（WriteBuffer[temp%128]）;

//DataBlock

SD_2Byte_Write（0xffff）;

//Send2BytesCRC

Response=SD_Read（）;

=0xffff）{;

temp++）//Provide8extraclock