SD卡电路，请用过的看看我的电路是否正确

[做一个码农都是奢望]

以下是我的sd卡电路图，一直未成功实现cmd0应答。请看是否电路有问题。

电路如下： 供电都是3.3v。

[做一个码农都是奢望]

请问 片选和 时钟clk需要上拉吗？

[Donbor]

VCC是3.3V你拉它干啥呀？
应该是限流电阻吧！

[aydf1]

硬件没错，应该是时序的问题吧

[做一个码农都是奢望]

通过测试，现在明确了，发送cmd0，应答是0xff。
说明：根本没有收到sd卡的应答；因为SPI读数据之前是发送了一个ff的。

[做一个码农都是奢望]

1.发送cmd0指令。

for (a = 0;a<0x0f;a++){SD_write_byte(0xff);}//wait  >74  Clk
	
	//--------- send CMD0  ---------
	U08 CMD[] = {0x40,0x00,0x00,0x00,0x00,0x95};//cmd0
	while((r1=SD_write_command (CMD)) !=0x01)
	{
		Uart_SendB(r1);//将应答发送出来。
		if (Timeout++ > 200)
		   { Uart_SendB(0xcc);return(1); }//测试是否未响应// CMD0 Error!  1
	}

2.被调用的函数 SD_write_command

//---------------------------------------------------------------------
//Send a Command to MMC/SD-Card
//Return: the second byte of response register of MMC/SD-Card
//---------------------------------------------------------------------
U08 SD_write_command (U08 *cmd)
{
	U08 tmp = 0xff;
	U16 Timeout = 0;

	SD_Disable();        //SD_CS = HIGH
	SD_write_byte(0xFF); //send 8 Clock Impulse
	SD_Enable();         //SD_CS = LOW   

	//send 6 Byte Command
    U08 a;
	for (a = 0;a<0x06;a++)  
		{
		  SD_write_byte(*cmd++);
		}

	//get 16 bit response
	while (tmp == 0xff)	
		{
		tmp = SD_read_byte();  //Only last 8 bit is used here.Read it out. 
		if (Timeout++ > 500){break;}
		}
	return(tmp);
}

3. SPI 发送和读取字节的命令。考虑模拟时序的问题。所用的avr单片机具备spi接口。

//---------------------------------------------------------------------
//Routine for reading a byte from MMC/SD-Card
//---------------------------------------------------------------------
inline U08 SD_read_byte (void)
{
	U08 Byte = 0,a=0;

    #if SPI_Mode	 
	  SPDR = 0xff;
	  while(!(SPSR & (1<<SPIF))){};
	  Byte = SPDR;
    #else			//Software SPI
	
	  for ( a=8; a>0; a--) //1 Byte  ( MSB First)
	      {
             SD_Write &=~(1<<SPI_Clock); //SD_SCK (Low) 
             delay();//启动延时
		     if (bit_is_set(SD_Read,SPI_DI) > 0)  
		        {
			    	Byte |= (1<<(a-1));
			     }
			  else
			     {
			         Byte &=~(1<<(a-1));
				  }
			   delay();//启动延时
		       SD_Write |=(1<<SPI_Clock); //SD_SCK (High)	
		        delay();//启动延时
		  }
    #endif
	return (Byte);
}

//---------------------------------------------------------------------
//Routine for sending a byte to MMC/SD-Card
//---------------------------------------------------------------------
inline void SD_write_byte (U08 Byte)
{
U08 a;
    #if SPI_Mode		 
	  SPDR = Byte; 	 
	  while(!(SPSR & (1<<SPIF))) {}
    #else			
	  for (a=8; a>0; a--) // 1 Byte ( MSB First)
	    {
		  if (bit_is_set(Byte,(a-1))>0)	{SD_Write |= (1<<SPI_DO); }//MMC.DO  High
		  else {SD_Write &= ~(1<<SPI_DO);}//MMC.DO  Low
		  delay();
		  SD_Write &= ~(1<<SPI_Clock);	//MMC.SCK  (LOW)
		  delay();
		  SD_Write |= (1<<SPI_Clock);   //MMC.SCK  (High)
		  delay();
	     }
	   SD_Write |= (1<<SPI_DO);	       //MMC.DO  High
    #endif
}

[做一个码农都是奢望]

1. cmd0指令

	//--------- send CMD0  ---------
	U08 CMD[] = {0x40,0x00,0x00,0x00,0x00,0x95};//cmd0
	while((r1=SD_write_command (CMD)) !=0x01)
	{
		Uart_SendB(r1);//将应答发送出来。
		if (Timeout++ > 200)
		   { Uart_SendB(0xcc);return(1); }//测试是否未响应// CMD0 Error!  1
	}

2.被调用的发送命令函数

//Send a Command to MMC/SD-Card
//Return: the second byte of response register of MMC/SD-Card
//---------------------------------------------------------------------
U08 SD_write_command (U08 *cmd)
{
	U08 tmp = 0xff;
	U16 Timeout = 0;

	SD_Disable();        //SD_CS = HIGH
	SD_write_byte(0xFF); //send 8 Clock Impulse
	SD_Enable();         //SD_CS = LOW   

	//send 6 Byte Command
    U08 a;
	for (a = 0;a<0x06;a++)  
		{
		  SD_write_byte(*cmd++);
		}

	//get 16 bit response
	while (tmp == 0xff)	
		{
		tmp = SD_read_byte();  //Only last 8 bit is used here.Read it out. 
		if (Timeout++ > 500){break;}
		}
	return(tmp);
}

3.SPI读写

//---------------------------------------------------------------------
//Routine for reading a byte from MMC/SD-Card
//---------------------------------------------------------------------
inline U08 SD_read_byte (void)
{
	U08 Byte = 0,a=0;

    #if SPI_Mode	 
	  SPDR = 0xff;
	  while(!(SPSR & (1<<SPIF))){};
	  Byte = SPDR;
    #else			//Software SPI
	
	  for ( a=8; a>0; a--) //1 Byte  ( MSB First)
	      {
             SD_Write &=~(1<<SPI_Clock); //SD_SCK (Low) 
             delay();//启动延时
		     if (bit_is_set(SD_Read,SPI_DI) > 0)  
		        {
			    	Byte |= (1<<(a-1));
			     }
			  else
			     {
			         Byte &=~(1<<(a-1));
				  }
			   delay();//启动延时
		       SD_Write |=(1<<SPI_Clock); //SD_SCK (High)	
		        delay();//启动延时
		  }
    #endif
	return (Byte);
}

//---------------------------------------------------------------------
//Routine for sending a byte to MMC/SD-Card
//---------------------------------------------------------------------
inline void SD_write_byte (U08 Byte)
{
U08 a;
    #if SPI_Mode		 
	  SPDR = Byte; 	 
	  while(!(SPSR & (1<<SPIF))) {}
    #else			
	  for (a=8; a>0; a--) // 1 Byte ( MSB First)
	    {
		  if (bit_is_set(Byte,(a-1))>0)	{SD_Write |= (1<<SPI_DO); }//MMC.DO  High
		  else {SD_Write &= ~(1<<SPI_DO);}//MMC.DO  Low
		  delay();
		  SD_Write &= ~(1<<SPI_Clock);	//MMC.SCK  (LOW)
		  delay();
		  SD_Write |= (1<<SPI_Clock);   //MMC.SCK  (High)
		  delay();
	     }
	   SD_Write |= (1<<SPI_DO);	       //MMC.DO  High
    #endif
}