看了很多资料，例程，但还是没有成功，可能哪里出了问题没发现，请大家帮我看看。以下是关键的3个函数，CMD0和CMD55返回的响应是0x01,但ACMD41返回的响应还是0x01,应该是0才对，但是怎么调试都不行，大侠帮看一下吧，先在此谢过了！
BYTE SD_SendCmd(BYTE cmd, BYTE *param, BYTE resptype, BYTE *resp)
{
WORD i; //所有SD卡命令都是6字节长
BYTE xdata tmp,rlen,Cmd_Buf[6];
char j;
if(cmd == CMD0)
Cmd_Buf[0] = 0x95; // 发送CRC校验码,只用于第1个命令(command0=40 00 00 00 00 95)
else //起始位为0（bit47），传输位为1(bit46)
Cmd_Buf[0] = 0xFF;
for(j = 3;j >=0;j --)
{
Cmd_Buf[j+1] = param[j]; //param[j]
}
Cmd_Buf[5] = (cmd & 0x3F) | 0x40;
if(cmd == CMD0) //先发送74个以上的时钟，为了使SD卡同步
{
SET_Slave_select(0);
// EZUSB_Delay(1);
for(i=0;i<10;i++)
SPI_Send_Byte(0xFF);
}
else
{
SET_Slave_select(0);
SPI_Send_Byte(0xFF);
}
SET_Slave_select(2);
//片选SPI从机
SPI_Send_Byte(Cmd_Buf[5]);
SPI_Send_Byte(Cmd_Buf[4]);
SPI_Send_Byte(Cmd_Buf[3]);
SPI_Send_Byte(Cmd_Buf[2]);
SPI_Send_Byte(Cmd_Buf[1]);
SPI_Send_Byte(Cmd_Buf[0]);
i = 0;
do // 等待响应,响应的最高位为0
{ //Wait for a response,a response is a start bit(zero)
tmp = 0xFF;
tmp = SPI_Rec_Byte(); //在没收到响应令牌之前,tmp=0xFF,因此tmp & 0x80==1,
i++;
}
while (((tmp & 0x80) != 0) && (i < SD_CMD_TIMEOUT)); //收到响应以后由于响应最高位是0,因此tmp & 0x80==0
if (i >= SD_CMD_TIMEOUT) //超时
{
// SPI_CS_Deassert(); //释放总线
TD_Poll(0x15);
EZUSB_Delay(2000);
TD_Poll(tmp);
EZUSB_Delay(2000);
SET_Slave_select(0);
return SD_ERR_CMD_TIMEOUT; // 返回命令超时 return response timeout of command
}
rlen = 0;
switch (resptype) //根据不同的命令,得到不同的响应长度
{ //according various command,get the various response length
case R1:
case R1B:
rlen = 1;
break;
case R2:
rlen = 2;
break;
case R3:
rlen = 5;
break;
default:
rlen = 1;
// SPI_Send_Byte(0xFF);
SPI_CS_Deassert();
return SD_ERR_CMD_RESPTYPE; // 返回命令响应类型错误 return error of command response type
break;
}
// EZUSB_Delay(1);
*resp = tmp;
for (j = rlen - 1; j >= 0; j--)
{
SPI_Send_Byte(0xFF); //resp的最高字节保存响应令牌Rx,其他字节装入0xFF
// SPI_Send_Byte(0xFF); // 发送周期的最后发送8clock at the last recycle,clock out 8 clock
}
SET_Slave_select(0);
return SD_NO_ERR; // 返回执行成功 return perform sucessfully
}
//////////复位/////////////
BYTE SD_ResetSD(void) /////
{
BYTE xdata param[4] = {0,0,0,0},ret,resp;
ret = SD_SendCmd(CMD0, param, CMD0_R, &resp); /* 复位命令 command that reset sd card */
if(ret != SD_NO_ERR)
{
return 1;
}
if(resp != 0x01)
{
TD_Poll(0x11);
EZUSB_Delay(2000);
TD_Poll(resp);
EZUSB_Delay(2000);
return 1;
}
return SD_NO_ERR;
}
///////////激活/////////////////
BYTE SD_Active(void)
{
BYTE xdata param[4] = {0,0,0,0},*resp1,*resp2,ret;
BYTE xdata i;
ret = SD_SendCmd(CMD55, param, CMD55_R, resp1); // 后续命令为一个应用命令
if (ret != SD_NO_ERR)
{
TD_Poll(0x21);
EZUSB_Delay(2000);
return ret; // command that the followed commnad is a specific application
}
if (*resp1 & 0x01 != 1 ) //CMD55响应值是0x01
{
TD_Poll(0x22);
EZUSB_Delay(2000);
// TD_Poll(*resp);
// EZUSB_Delay(2000);
return SD_ERR_CMD_RESP; // 响应错误 response is error
}
i = 0;
do // 循环发出CMD55+ACMD41, 查询卡的状态
{
ret = SD_SendCmd(ACMD41, param, ACMD41_R, resp2);
if (ret != SD_NO_ERR)
{
TD_Poll(0x23);
EZUSB_Delay(2000);
return ret;
}
i++;
}while ((i < 200)&& (*resp2 != 0));/* 如果响应R1的最低位Idle位为1,则继续循环 */
if (i >= 200)
{
TD_Poll(0x24);
EZUSB_Delay(2000);
TD_Poll(*resp2);
EZUSB_Delay(2000);
return SD_ERR_TIMEOUT_WAITIDLE; // 超时,返回错误 time out,return error
}
if (*resp2 != 0)
return SD_ERR_CMD_RESP; //响应错误 response is error
return SD_NO_ERR; // 读出寄存器内容 read the content of the register
}
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