单片机读写SD卡教程

1、郑重声明：本实验并不是对所有SD卡都能成功运行第一步：打开 win hex软件，用读卡器读 SD卡，在win hex中查看SD卡FPrlrj旧nmg *御日曲日尺立件（日轄:号iifllPI讥吵：当Tfllll春罰;I SW（£）旨口凹帶此|；也S X电a O C3* -0畫*电bld! IbiljUA 初1 悶1|馆口曲佃AgraaSBJLXsta InAEiqptetEJ'03839535e on(«»： 0 16BH(*J-)： 0曲* ?；第詞EKt £i2f UrEiib&d MT 1 SOB66.5 K01.2 MBFamof

2、跆hl色 TipHium 1Offset0123456739ABcnEF/1ModSfA'v wC Cans AedefDOOOOODDEc0000OD0000DOaa00000000DOaoDOoofc 1j uFirmwlrf Atv.1.D0OCIIDOOOIQ00000000oo0000OiO00no0000GOnono00.DUS：USBD000002D000000000000DO00：ir000000DO00DOaoI! DerauitEdnDD00003D0000000000aoDOaa00000000DOa)aDOaai j 4Sl5te:originaloomoQQi

3、n0000000000ononOQ00no000000QiQ0000. .Undo lewef:000000050oa0000000000DOOQ00000000m00DOQOr i, fUndo rsverses:MaD000006D00OD000000aoDOaa000000aoDOo)aDOaa-oonoau70on0000OQ0000DOoaoaOQ00QO00aoDO00. 1.7,1126.576 诩跆DOOaOOBDoa0000000000DOOQ00000000m00DO00r 1D000009D00OD000000aoDOaa000000aoDOa)aDOoaii iJ 4S

4、iapkis seclorfi 创 entE51 3DOOQOaM)000000OQ0000noa>a00000000do00DO-”4 4OOOOOOBDoa0000000000DOOU00000000DO00DO00r i1 fPsritllfln:-：1DOOOOOCD000000aa00aoDOaa000000aoDOa)oDOoah ij 4RcISWb S-BCbOr HoNaOOOOOODD00QOm00000000no0000GO00DO0000aomdcJb:hiBoodewnalOOOOOOED000000000000DOao000000000000DO00, ,Cu

5、aiader 虻I ANSI ASCIIoooaaoFD00OD0000DOaoDOaa00000000DOa)aDOaoOR 曲：hexadecwnaloomoaioo000000OQoo00noaa00OQ0000lOOQiO00DOoooaoiiD000000000000DO Q00000000m00DO00r ilnllnuiiw *.1No ofwIridcrBVK'ID000012D00OD000000aoDOaa000000aoDOa)aDOoaii iJ 4D000013Qoo00oo00oo00ooaooonodoQfloooo00so加 Aab 用00000140D

6、U0000000000DOQO00000000DOaoDO00,.TEMPltilifer 1.2GBffeeD000015D00OD00OQ00aoDOaa000000aoDOa)aDOaaB 1J4Dmini-iilOCalS'1 打 ampQOOOQ1BO00QO00QOoo00DOaa00000000lOOQiO00DO.tJ00000170000000000000DO0000000000uo00DO00r i1 1J4D00001BD000000OQ00aoDOaa000000aoDOa)oDOoa“.J -SedamoT胡4加轴0tT9«l：a=DBlatk-Pa

7、rHion 1Siad BecWrsUnp3it(jonb*5 阿苗点击查找（ctrl+F ）Find Text33JJJJJJJJ3 The folouing text string wil be searched: FAT|caseASCII/Code page vUse this as a wildcardI I Whole wo(d odjjSearch: Cond.: offset mod=I_ Search in plgk onlySearch in dll open windows| List search hits, 14)to1Cancel输入FAT （找到 DBR处）Off

8、set0123电567a9ABcDEF0001H70FFFFFFFFFFFFFFFFaFFFFVVFFFFFFFFFFyyyyyyyyyyyyyyyyU0C11160FFFFFfFFFFFFFFFFFFFFFFFFFFFFFFFfyyyyyVyyyyyyyyyy0011190FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFyyyyyyyyyyyyyyyyQDQ111A0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFyyyyyyyyyyyyyyyy000111B0FFFFFFFFFFFFFFFFFFFFFFFFFFfFFFFFD0011ICOFFFFFfFFFF

9、FFFFFFFFFFFFFFFFFFFFFF DinillDOFFFFFFr rFFFFFFFFFFFFFFFFFFFFFFFFyyyyyyyyyyyyyyyy000111E0FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFvyyyyvyyy/yyywaooniFOFFFFFfFFFFFFFFFFFFFFFFFFFFFFFFFFyyyyyjyyyyyyyyD0011200EB3CEID4D53444F53352E30cm024口02QO承晦 DOSiS.EL甩000112100200Q200ooFBEB003FQ0FF0089000000，ta, ?. y, I,0001122

10、0779F3A0000DO29DE04D3B44E4F204E41. r. Jk.OlMO NA00112304D目52D20202D46415431362D20203309MEflATlG3E00112408EDLBCFO7BBED9BEa209ECDFCBD007C倔曲nil". iXm.|0001125039怔7C24旳Cl99EQ3C0172IC63EB3Aetn)siAu<,rU001126066Al1C70茁663B0726BA57FC7506CDCAfl. i&r；xiwuti.i£DOO1127002Be5E02soC31073EH33C9BA

11、46109BF7H IV.lI.sa3EIF.lroaonzao6616Q3461C1356IE0346OE13DI日E7611f.,F.V.F,Rlv.000112906D89416FC0956FEB82000F7E6cB5EOB03' IFulVp.DOO11ZAOC346F7F3014&FC114EFE610F00 0EBE6AH-o.Fi;ilse0OT112B0007239263B2n7417BlQBBEAl7DF3A6Br9&H-t土用I q000112C0617432冲E”0983C72 a3BFB72E6EBDCAOat2NtdC : tirU00011

12、2D0FB7DB47D0BFOAC90电d74OC407413B4OEa' i-.nooiizEOBE07 CD10EBEFAOFH7DEBEEiAOFC7DEB> -.I ,ei y se iieOQOnZFOElCD16CD19268BB001BE0000E8.i .£iu.rd.».551A52Data Initerfihetetl7D9i rzTtnIF.1 R71RemoibiB medium 1 MadBDJhlMC Cam ReaderFirnlware Rev2 1 JOBil8：USBDeraun Edit ModeSials:oripiir

13、ul!UndD I 眈 I；QUndo rarerses:矶Tolai apacifr： 1l.& GB 1.907,129,57 a byltlByles- persBdDr:51JSurplU*別 eni?51 3Parti tiori:1RelalM ecbor No.:ModsT旳Charader set ANSI ASCIP hmdeclmsiiEMbb per page*: 25x161400VMndow r1No. ufvflndcws:1Clipboard:a MailableTEMPMder UGShH JiDMiNMlLOCALS-1 Tempcmu)a m v &

14、quot;c d n发现DBR起始于0x11200扇区地址，它必是512整数倍，因为一个扇区含 512BYTE，所以 在程序中读一个扇区时一定要是 512整数倍，否则会出错。 11200地址对应的值是0xEB， 本程序读一下这个地址的值看看是否正确。注意有的win hex编址是十进制看看程序吧#in elude <reg52.h>#defi ne uchar un sig ned char#defi ne uint un sig ned int/=/定义SD卡需要的4根信号线sbit SD_CLK = P1A1;sbit SD_DI = P1A2;sbit SD_DO = P1A0

15、；sbit SD_CS = PU3;sbit Beep=P2A0；用来调程序标志 /=/=/定义512字节缓冲区，89C52直接定义成 unsigned char DATA80;，太大了 RAM不够 un sig ned char xdata DATA512;void delay (un sig ned int z)un sig ned int x,y; for(x=z;x>0;x_);for(y=110;y>0;y-);/= /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;

16、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=1;SD_CLK=0;n<<=1;if(SD_DO) n|=1;return n;/= /检测 SD 卡的响应unsigned char SdResponse()uchar i=0,response=0;while(i<=8)response = SdRead(); if(respons

17、e=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);SdW

18、rite(unsigned char *)&argument)3);*/SdWrite(argument>>24);SdWrite(argument>>16);SdWrite(argument>>8);SdWrite(argument);SdWrite(CRC);/= /初始化 SD 卡unsigned char SdInit(void)unsigned char i;unsigned char response=0xFF;P3=0xff;SD_CS=1;for(i=0;i<=0xfe;i+)SdWrite(0xff);SD_CS=0;SdCo

19、mmand(0x00,0,0x95);SD_DI=1; response=SdResponse();if(response!=0x01)return 0;if(response=0x01) / 不管什么 SD 卡都能进入这一步，同时也说明硬件没问题 SD_CS=1;/Beep=0;/while(1);/ 用来查看程序能否运行到这一步，去掉/即可SdWrite(0xff);SD_CS=0;while(1)SdCommand(0x01,0,0xff);/SdCommand(0x01,0x00000000,0xff);/ 进 SPI response=0xff;SD_DI=1; for(i=0;i&

20、lt;250;i+)/response!=0x00/ 等待回复 response=SdResponse(); /Beep=0;/ if(response=0) break;if(response=O) break;/回复0则通过SPI，只要通过 SPI后面的指令才能继/续/Beep=0;/Beep=0;看程序能否跳出来，挑不出来则进不了SPISD_CS=1;SdWrite(0xff);SD_CS=0;/Beep=0;return 1;/=/往 SD 卡指定地址写数据 ,一次最多 512 字节 最好不要乱写 否则 fat 系统被改掉 SD 卡打不 开unsigned char SdWriteBl

21、ock(unsigned char *Block, unsigned long address,int len)unsigned int count;unsigned char dataResp;SD_CS=0;SdCommand(0x18,address,0xff);if(SdResponse()=00)SdWrite(0xff);SdWrite(0xff);SdWrite(0xff);/command was a success - now send data/start with DATA TOKEN = 0xFESdWrite(0xfe);/now send datafor(count

22、=0;count<len;count+) SdWrite(*Block+); for(;count<512;count+) SdWrite(0);/data block sent - now send checksumSdWrite(0xff); / 两字节 CRC 校验 , 为 0XFFFF 表示不考虑 CRCSdWrite(0xff);/Now read in the DA TA RESPONSE token dataResp=SdRead();while(SdRead()=0); dataResp=dataResp&0x0f; /mask the high byte of the DATA RESPONSE token SD_CS=1;SdWrite(0xff); if(dataResp=0x0b) return 0;if(dataResp=0x05)return 1;return 0;/printf("Command 0x18 (Write) was not received by the SD.n"