Micro SD卡写扇区操作 - 智能车制作

// 初始化SD卡到SPI模式
unsigned char SD_Reset()
{
unsigned char retry,temp;
unsigned char i;
unsigned char CMD0[] = {0x40,0x00,0x00,0x00,0x00,0x95};
SD_CS_SetVal();
for (i=0;i<10;i++)
SD_SPI_SendChar(0xFF); //发送至少74个时钟信号
SD_CS_ClrVal();
//向SD卡发送CMD0
retry=0;
do
{
//为了能够成功写入CMD0,在这里写200次
for(i=0;i<5;i++)
SD_SPI_SendChar(0xFF); //发送至少16个时钟信号
temp=Write_Command_SD(CMD0);
retry++;
if(retry==200)
{ //超过200次
return(0x01);//CMD0 Error!
}
}
while(temp!=0x01); //回应01h，停止写入
SD_CS_SetVal();
SD_SPI_SendChar(0xFF);
return 0;
}
unsigned char SD_Init()
{
unsigned char retry,temp;
unsigned char CMD1[] = {0x41,0x00,0x00,0x00,0x00,0xFF};
//发送CMD1到SD卡
SD_CS_ClrVal();
retry=0;
do
{ //为了能成功写入CMD1,写100次
temp=Write_Command_SD(CMD1);
retry++;
if(retry==100)
{ //超过100次
return(0x02);//CMD1 Error!
}
}
while(temp!=0x00);//回应00h停止写入
SD_CS_SetVal(); //片选无效
SD_SPI_SendChar(0xFF);
return(0); //初始化成功
}
//-----------------------------------------------------------------------------------------------
// 向SD卡中写入命令，并返回回应的第二个字节
//-----------------------------------------------------------------------------------------------
unsigned char Write_Command_SD(unsigned char *CMD)
{
unsigned char *temp=0;
unsigned char retry=0;
unsigned char i;
//禁止SD卡片选
SD_CS_SetVal();
//发送8个时钟信号
SD_SPI_SendChar(0xFF);
//使能SD卡片选
SD_CS_ClrVal();
//向SD卡发送6字节命令
for (i=0;i<6;i++)
{
SD_SPI_SendChar(*CMD++);
}
//获得16位的回应
SD_SPI_RecvChar(temp); //read the first byte,ignore it.
do
{ //读取后8位
SD_SPI_RecvChar(temp);
retry++;
}
while((*temp==0xFF)&&(retry<100));
return(*temp);
}
//--------------------------------------------------------------------------------------------
// 写512个字节到SD卡的某一个扇区中去返回0说明写入成功
//--------------------------------------------------------------------------------------------
unsigned char SD_write_sector(unsigned long addr,unsigned char *Buffer)
{
unsigned char tmp,retry;
unsigned char *temp=0;
unsigned int i;
//命令24
unsigned char CMD24[] = {0x58,0x00,0x00,0x00,0x00,0xFF};
addr = addr << 9; //addr = addr * 512
CMD24[1] = (unsigned char)((addr & 0xFF000000) >>24 );
CMD24[2] = (unsigned char)((addr & 0x00FF0000) >>16 );
CMD24[3] = (unsigned char)((addr & 0x0000FF00) >>8 );
SD_CS_ClrVal();
//写命令24到SD卡中去
retry=0;
do
{ //为了可靠写入，写100次
tmp=Write_Command_SD(CMD24);
retry++;
if(retry==100)
{
return(tmp); //send commamd Error!
}
}
while(tmp!=0);
//在写之前先产生100个时钟信号
for (i=0;i<100;i++)
{
SD_SPI_RecvChar(temp);
}
//写入开始字节
//SD_CS_ClrVal();
SD_SPI_SendChar(0xFE);
//现在可以写入512个字节
for (i=0;i<512;i++)
{
SD_SPI_SendChar(Buffer[i]);
}
//CRC-Byte
SD_SPI_SendChar(0xFF); //Dummy CRC
SD_SPI_SendChar(0xFF); //CRC Code
SD_SPI_RecvChar(temp); // read response
if((*temp & 0x1F)!=0x05) // 写入的512个字节是未被接受
{
SD_CS_SetVal();
return(0x03); //Error!
}
//等到SD卡不忙为止
//因为数据被接受后，SD卡在向储存阵列中编程数据
do
{
SD_SPI_RecvChar(temp);
}
while (*temp!=0xFF) ;
//禁止SD卡
SD_CS_SetVal();
SD_SPI_SendChar(0xFF);
return(0);//写入成功
}

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