//實驗目的：學習SD卡的操作

//軟件設計
//??????? 1、SD卡采用SPI通信
//??????? 2、先往SD里順序寫入0-255共256個數據，然后再讀回送LCD1602顯示
//硬件要求：
//??????? 撥碼開關S11置ON
//??????? 跳線J18全部接通

#include ???????????? //dsPIC30F6014標準頭文件

? _FOSC(CSW_FSCM_OFF & XT_PLL4);? //4倍頻晶振，Failsafe 時鐘關閉
? _FWDT(WDT_OFF);???????????????? //關閉看門狗定時器
? _FBORPOR(PBOR_OFF & MCLR_EN);?? //掉電復位禁止，MCLR復位使能。
? _FGS(CODE_PROT_OFF);??????????? //代碼保護禁止

#define? cs? PORTGbits.RG9??????? //定義SD卡片選腳

#define rs LATBbits.LATB4???????? //定義LCD控制位(注意這里只能用LATB寄存器，不能直接用PORTB寄存器）
#define rw LATBbits.LATB5
#define e? LATBbits.LATB6

unsigned char __attribute__((address(0x900))) lcd[3]={0,0,0};

void? spi_init();???????????????? //申明系統初始函數
void? spi_low();????????????????? //申明產生低波特率函數（SD卡初始化使用）
void? spi_high();???????????????? //申明產生高波特率函數（SD卡初始化后使用）
unsigned char sd_reset();???????? //申明SD卡初始化函數
unsigned char SD_SendCommand(unsigned char cmd,unsigned long arg); //申明寫SD卡命令函數
unsigned char SPI_WriteByte(unsigned char val);??????????????????? //申明寫一字節(jié)函數
unsigned char SPI_ReadByte(void);????????????????????????????????? //申明接收一字節(jié)函數
unsigned char SD_WriteSingleBlock(unsigned long sector);?????????? //申明寫SD卡單BLOCK數據函數
unsigned char SD_ReadSingleBlock(unsigned long sector);??????????? //申明讀SD卡單BLOCK數據函數
void lcd_display();??????????????????????????????????????????????? //申明結果顯示函數
void? delay();???????????????????????????????????????????????????? //申明延時函數（顯示時用）

//系統初始化函數
void spi_init()
{
? TRISG=0x00d0;??????????????????????? //設置SDI為輸出，其他C口為輸出
? TRISB=0X0000;??????????????????????? //設置B口為輸出
? TRISD=0X0000;??????????????????????? //設置D口為輸出
? SPI2CON=0x0278;????????????????????? //空閑時總線為高電平，fosc/64
? SPI2STAT=0x8000;???????????????????? // 輸出數據的末尾采樣輸入數據，上升沿發(fā)送數據
}

//*************************寫LCD程序****************************************
//寫一個字節(jié)數據函數
//在電平發(fā)生改變后需要插入一段延時時間，否則LCD反應不過來。
void write(unsigned char x)
?{
? PORTD=x;?????????????????? //待顯示數據送PORTD口
? delay();??????????????????
? rs=1;????????????????????? //該字節(jié)數據為數據，而不是命令
? delay();
? rw=0;????????????????????? //此次操作為寫，而不是讀
? delay();
? e=0;?????????????????????? //拉低使能信號
? delay();?????????????????? //保持使能信號為低一段時間
? e=1;?????????????????????? //拉高使能信號，建立LCD操作所需要的上升沿
? delay();
?}

//********************LCD顯示設置函數**************************************
//在電平發(fā)生改變后需要插入一段延時時間，否則LCD反應不過來。
void lcd_enable()
?{
?? delay();
?? rs=0;???????????????????? //該字節(jié)數據為命令，而不是數據
?? delay();
?? rw=0;???????????????????? //此次操作為寫，而不是讀
?? delay();
?? e=0;????????????????????? //拉低使能信號
?? delay();????????????????? //保持使能信號為低一段時間
?? e=1;????????????????????? //拉高使能信號，建立LCD操作所需要的上升沿
?? delay();
}

//*********************LCD初始化函數**************************************
void lcd_init()
?{
??? PORTD=0X1;???????????????? //清除顯示
??? lcd_enable();
??? PORTD=0X38;??????????????? //8位2行5*7點陣
??? lcd_enable();
??? PORTD=0X0e;??????????????? //顯示開，光標開，閃爍
??? lcd_enable();
??? PORTD=0X06;??????????????? //文字不動，光標右移
??? lcd_enable();
??? PORTD=0X86;??????????????? //時間顯示地址
??? lcd_enable();
?}

//***********************LCD顯示函數************************************
void lcd_display()
?{?
??? unsigned char i,j;
??? lcd_init();
??? for(i=0;i<3;i++)????????? //一共3字節(jié)數據
?????? {
???????? write(lcd[i]);?????? //查表獲取數據并調用寫一個字節(jié)數據函數送LCD顯示
???????? for(j=0;j<5;j++)???? //延時一段時間（主要是為了控制顯示的速度）
????????? {delay();}
?????? }
?}

//****************寫一字節(jié)函數***************************
unsigned char SPI_WriteByte(unsigned char val)
{
?SPI2BUF = val;??????????????? //待發(fā)送數據裝載到發(fā)送寄存器
?while(!IFS1bits.SPI2IF);????? //等待發(fā)送完成
??? IFS1bits.SPI2IF=0;??????????? //清除發(fā)送完成標志位
?return SPI2BUF;?????????????? //讀取接收寄存器（即使是無效數據也需清空）
}

//****************接收一字節(jié)函數**************************
unsigned char SPI_ReadByte(void)
{
?SPI2BUF = 0xff;?????????????? //發(fā)送寄存器裝載數據，以啟動數據接收
?while(!IFS1bits.SPI2IF);????? //等待接收完成
??? IFS1bits.SPI2IF=0;??????????? //清除接收完成標志位
?return SPI2BUF;?????????????? //讀取接收到的數據
}

//*****************發(fā)送命令函數****************************
unsigned char SD_SendCommand(unsigned char cmd,unsigned long arg)
{
?unsigned char r1;
?unsigned char retry1=0;????? //重復操作次數
?
?cs=0;??????????????????????? //使能片選信號
?
?SPI_WriteByte(cmd | 0x40);?? //分別寫入命令
?SPI_WriteByte(arg>>24);????? //數據段第4字節(jié)
?SPI_WriteByte(arg>>16);????? //數據段第3字節(jié)
?SPI_WriteByte(arg>>8);?????? //數據段第2字節(jié)
?SPI_WriteByte(arg);????????? //數據段第1字節(jié)
?SPI_WriteByte(0x95);???????? //CRC效驗和
?
?while((r1 = SPI_WriteByte(0xff)) == 0xff)//等待響應
??if(retry1++ > 200) break;//超時退出?????
????
?cs=1;??????????????????????? //清初片選信號

?return r1;?????????????????? //返回狀態(tài)值
}

//*******************SD開初始化函數**************************
unsigned char sd_reset()
{
?unsigned char i,tmp;
?unsigned char retry;??????????? //重復次數
?unsigned char r1=0;?????????????
?retry=0;
?delay();
?delay();
?do
?{
??????? for(i=0;i<100;i++) SPI_WriteByte(0xff);
?????
??r1 = SD_SendCommand(0,0);//發(fā)idle命令?
??retry++;
??if(retry>20) return 1;?? //超時退出?
?} while(r1 != 0x01);????? //等待IDLE命令返回

?retry = 0;???????????????????
??? cs=0;
??do
?{
??????? for(i=0;i<100;i++) SPI_WriteByte(0xff);

??r1 = SD_SendCommand(1, 0);???????? //發(fā)Active命令
??retry++;
??if(retry>254) return 1;??????????? //超時退出
?????? } while(r1);??

??? for(i=0;i<100;i++) SPI_WriteByte(0xff);

?r1 = SD_SendCommand(59, 0);??????????? //關crc?
?? if (r1) return 1;????????????? //返回不正確，退出初始化

?for(i=0;i<100;i++) SPI_WriteByte(0xff);

??? r1 = SD_SendCommand(16, 512);????????? //設扇區(qū)大小512
??? if(r1!=0) return 1;??????????????????? //返回不正確，退出初始化
?return 0;????????????????????????????? //正常返回?
}

//********************寫一個扇區(qū)**************************?
unsigned char SD_WriteSingleBlock(unsigned long sector)
{
?unsigned char r1;
?unsigned int i;
??? unsigned char retry=0;
?do
?{
??????? for(i=0;i<100;i++) SPI_WriteByte(0xff);

??r1 = SD_SendCommand(24, sector<<9);//寫命令
??retry++;
??if(retry>10) return 1;???????????? //超時退出?
?} 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);????????????????? //發(fā)開始符
?
?for(i=0; i<512; i++)????????????????? //送512字節(jié)數據
?{
??????? if(i<255) SPI_WriteByte(i);?????? //發(fā)送0--255
??else SPI_WriteByte(512-i);??????? //發(fā)送255--0
????????
?}
?
?SPI_WriteByte(0x95);
?SPI_WriteByte(0x95);???????????????? //16-bits CRC

?r1 = SPI_WriteByte(0xff);??????????? //讀響應位
??? if(retry++ >10) return 1;??????????? //超時退出
??? while(!((r1&0x0f)==5));????????????? //等待數據成功接受返回信息
??? while(!(SPI_WriteByte(0xff)));?????? //等待SD卡內部編程完成
??
?return 0;
}
?????

//******************讀SD卡一個扇區(qū)************************
unsigned char SD_ReadSingleBlock(unsigned long sector)
{
?unsigned char r1,temp;
?unsigned int i,j;
?unsigned char retry=0;

?do
?{
??r1 = SD_SendCommand(17, sector<<9);//讀命令
??retry++;
??if(retry>10) return 1;???????????? //超時退出
?} while(r1 != 0x00);?
?cs=0;
?while(SPI_WriteByte(0xff)!= 0xfe)????? //等待接收到開始字節(jié)
???? {
?????? if(retry++ >100) return 1;????????? //超時退出
???? }
?for(i=0; i<512; i++)?????????????????? //讀512個數據
?{
??temp = SPI_WriteByte(0xff);??????? //讀取接收到的數據
??????? lcd[0]=(temp/100)+48;
??????? lcd[1]=((temp%100)/10)+48;
??????? lcd[2]=((temp%100)%10)+48;
??????? lcd_display();???????????????????? //讀取數據送顯示
??????? for(j=0;j<500;j++) {delay();}
?}

?SPI_WriteByte(0xff);?????????????????? //偽16-bits crc
?SPI_WriteByte(0xff);
?
?cs=1;

?return 0;
}

//***********************延時程序*************************
void? delay()????????????? //延時程序
??? {
???? int i;???????????????? //定義整形變量
???? for(i=0x100;i--;);???? //延時
??? }

//************************主函數**************************???
int main(void)
{
???? unsigned char loop,res;
???? delay();
???? delay();
???? delay();
???? loop=1;
????
???? cs=1;
???? while(loop)
???? {
??????? spi_init();??????????????????? //調用系統初始化函數
??????? res= sd_reset();?????????????? //調用SD卡初始化函數
??????????? if(res) break;???????????? //SD卡初始化是否正常，不正常，退出循環(huán)，不執(zhí)行下面的讀寫操作
??????? SD_WriteSingleBlock(1);??????? //調用寫SD卡單BLOCK函數，其中扇區(qū)號為1
??????????? if(res) break;
??????? SD_ReadSingleBlock(1);???????? //調用讀SD卡單BLOCK函數，其中扇區(qū)號為1
?????????? if(res) break;
??????? loop=0;
???????? while(1);
???? }
???? while(1);
}???