SDIO学习

SDIO学习

内容提要

---

摸索SD操作许久，发现很多资料都是基于库函数开发，为真正理解SDIO的操作流程，本文引导读者一起去阅读Spec文件，深入理解SDIO操作的来龙去脉。（注意：本文主要是自己的学习心得，记录学习中感觉重要的知识点，细节还需参考Spec）

协议手册

---

SDIO操作协议主要包括两个部分

• SDIO接口协议 SDIO Card Specification：SDIO接口操作SD/MMC等的规范
• SD物理层协议 SD Specifications Physical Layer Spec：SD卡的操作规范

SD卡结构

---

如上图所示，SD卡主要包括输入输出引脚、卡接口控制器、电源管理、内部寄存器、Memory接口和Memory组成。

协议理解

---

总线数据传输协议

---

command和response通过双向传输线CMD传输
command表示SDIO接口传输给SD卡的指令，response表示SD卡传输个SDIO接口的信息
数据可以是1bit或4bit通过DAT传输（data0/data0-3）
数据线DAT是双向的，SDIO通过它进行SD卡的读写操作

CMD结构

---

CMD命令结构

---

每条指令由起始位（1bit）、传输位（1bit）、命令索引（6bit）、CRC校验（7bit）和结束位（1bit）组成，总长48bit。
传输位标识传输的方向，SDIO（host）传输的为command，transmmitter bit = 1

Responds类型

---

SD卡的response有多种类型，请参考Spec文档。
response主要包含SD卡的内部寄存器内容和状态信息，在操作过程中需密切关注。
传输位标识传输的方向，SD（host）传输的为response，transmmitter bit = 0

数据结构

---

SDIO支持1bit和4bit数据传输，数据发送通过移位寄存器进行串行处理

SD读写操作

---

卡状态与操作模式

---

卡状态可以通过response或CMD13得到，标识SD操作的状态
操作模式是上电操作一般的过程

初始化

---

上电后，需要识别SD卡的类型，得到SD卡的状态信息，并将SD置于stand-by模式，故需要进行初始化

初始化的步骤（SDHC卡为例）

• 发送CMD0，将卡状态复位到idle状态。
• 发送CMD8，得到response。
• 持续发送ACMD41（CMD55+CMD41），检测response的CCS（30bit），若CCS = 1，则为高容量卡，检测识别是否完成response的finish（31bit）= 1执行下一步。
• 发送CMD2得到CID信息
• 发送CMD3得到SD卡地址信息（RCA）初始化完成，进入到stand-by模式

传输状态

---

• 如图所示，通过发送不同的CMD，切换SD的状态
• 注意状态的转移情况

卡状态确认

---

• 卡状态可以通过CMD13查看SD卡所处的状态，确认操作正确与否

参考代码

---

void SDIORead_Test(){
    int rca;
    int complete;
    int current_status;
    int error_status;
    int i;
    int n = 1000;
    int temp = 0;
    
    int rxdata0 = 0;
    int rxdata1 = 0;
    int rxdata2 = 0;
    int rxdata3 = 0;

    uart_printf("Start testing SDIO tranfer...
");

    SDIO1_GPIOInitRemap(); //配置GPIO

//======================================================
// set up
// Test:  Init sequence, With response check  
// CMD 0  Reset Card
// CMD 8  Get voltage (Only 2.0 Card response to this)            ////
// CMD55  Indicate Next Command are Application specific
// ACMD44 Get Voltage windows
// CMD 2  CID reg
// CMD 3  Get RCA.
//======================================================

    //配置MCU的SDIO（根据不同的SDIO而定）
    SDIO1->MMC_CARDSEL = 0xdf;   //enable module, enable mmcclk
    SDIO1->MMC_CTRL    = 0x83;      //4bit,low speed,1/16 divider		
    SDIO1->MMC_INT_MASK = 0x01;  //unmask interrupt
    SDIO1->MMC_CRCCTL   = 0xC0;  

//======================================================
//reset card :CMD0
//======================================================
    CMD_Send(0,0);
		
    n = 100;
    while(n--);
//======================================================
//cmd 8 
//======================================================
    CMD_Send(8,0x1AA);
    
    n = 1000;
    while(n--);
 		
    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD8 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }

    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 =  SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    
    n = 100;
    while(n--);
		
while(1)
{	
//======================================================
//cmd 55 
//======================================================
    CMD_Send(55,0);
		n = 1000;
    while(n--);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD55 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    
    n = 100;
    while(n--);
//======================================================
//acmd 41 
//======================================================
		CMD_Send(41,0xC0100000);
		n = 1000;
    while(n--);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD41 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);
		
   if(!(rxdata0>>30 & 0x1)){  //判断CCS，CCS=1为高容量卡
   	  uart_printf("CCS = 0
");
   }
   else{
   	  uart_printf("CCS = 1   High Capacity SD Memory Card
");			
   }
     		
   if(!(rxdata0>>31 & 0x1)){  //判断电压设置，上电是否完成
   	  uart_printf("Finished = 0
");
   }
   else{
   	  uart_printf("Finished = 1
");			
   }
    
    n = 100;
    while(n--);	
		
    if((rxdata0>>31 & 0x1)){
	  break;             //上电完成退出循环 
    }		

}
//======================================================
//cmd 2 CID
//======================================================
    CMD_Send(2,0);

    SDIO1->MMC_IO = 0x1c;  //auto only response transfer (136bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD2 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF7<<24  |SDIO1->CMD_BUF6<<16  |SDIO1->CMD_BUF5<<8  | SDIO1->CMD_BUF4;
    rxdata2 = SDIO1->CMD_BUF11<<24 |SDIO1->CMD_BUF10<<16 |SDIO1->CMD_BUF9<<8  | SDIO1->CMD_BUF8;
    rxdata3 = SDIO1->CMD_BUF15<<24 |SDIO1->CMD_BUF14<<16 |SDIO1->CMD_BUF13<<8 | SDIO1->CMD_BUF12;
    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);
    uart_printf("rxdata2 = %x.
",rxdata2);
    uart_printf("rxdata3 = %x.
",rxdata3);
    
    n = 100;
    while(n--);
//======================================================
//cmd 3 RCA  :得到RCA，后续传输需要
//======================================================
    CMD_Send(3,0);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD3 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    uart_printf("RCA = %x.
",(unsigned int)rxdata0>>16);		
    
    rca = (unsigned int)rxdata0>>16;
		
    n = 100;
    while(n--);

		
//======================================================
//cmd 9 + RCA -> CSD
//======================================================
    CMD_Send(9,rca<<16);

		uart_printf("
RCA << 16 = %x
",(unsigned int)rca<<16);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD9 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF7<<24  |SDIO1->CMD_BUF6<<16  |SDIO1->CMD_BUF5<<8  | SDIO1->CMD_BUF4;
    rxdata2 = SDIO1->CMD_BUF11<<24 |SDIO1->CMD_BUF10<<16 |SDIO1->CMD_BUF9<<8  | SDIO1->CMD_BUF8;
    rxdata3  = SDIO1->CMD_BUF15<<24 |SDIO1->CMD_BUF14<<16 |SDIO1->CMD_BUF13<<8 | SDIO1->CMD_BUF12;
    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);
    uart_printf("rxdata2 = %x.
",rxdata2);
    uart_printf("rxdata3 = %x.
",rxdata3);
		
    n = 100;
    while(n--);
//======================================================
//cmd 13 status  stand-by 
//======================================================
while(1){	
    CMD_Send(13,rca<<16);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD13 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    
    n = 100;
    while(n--);			

		current_status = (rxdata0>>9) & 0xf;
		error_status   = (rxdata0>>19) & 0x1;
		uart_printf("
 current_status = %x.
",current_status);
		uart_printf("
 error_status = %x.
",error_status);
		
		if(current_status == 3){
			break;
		}
}		
		
//======================================================
//cmd 4 设置频率
//======================================================
    CMD_Send(4,0x04040000);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD4 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    n = 100;
    while(n--);
		SDIO1->MMC_CTRL    = 0xc3;      //4bit,high speed,1/2 divider	
//======================================================
//cmd 7  
//======================================================
    CMD_Send(7,rca<<16);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD7 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);
		
    n = 100;
    while(n--);		

	
//======================================================
//cmd 13 status   tran mode
//======================================================
while(1){	
    CMD_Send(13,rca<<16);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD13 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    
    n = 100;
    while(n--);			

		current_status = (rxdata0>>9) & 0xf;
		uart_printf("current_status = %x.
",current_status);
		
		if(current_status == 4){
			break;
		}
}		
//======================================================
//cmd 55 
//======================================================
    CMD_Send(55,rca<<16);
		n = 1000;
    while(n--);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
//           uart_printf("Recieve CMD55 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

//    uart_printf("rxdata0 = %x.
",rxdata0);
//    uart_printf("rxdata1 = %x.
",rxdata1);

    
    n = 100;
    while(n--);		
//		
//======================================================
//acmd 6  设置bus宽度
//======================================================
    CMD_Send(6,0x2);  //4bit

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD6 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    
    n = 100;
    while(n--);	

//======================================================
//cmd 16  
//======================================================
    CMD_Send(16,0x200);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD16 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;
    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);
	
		
    n = 100;
    while(n--);		
	
//======================================================
//cmd 17 read data 
//======================================================
//    CMD_Send(17,0x300);

    CMD_Send(17,0x0);		

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD17 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);
		
    n = 100;
    while(n--);		

    complete = SDIO1->BUF_CTL & 0x1;
    uart_printf("

complete = %d.

",complete);
//======================================================
//read data
//======================================================
    SDIO1->BUF_CTL         = 0x020;    //disable dma, read sd card
    SDIO1->MMC_IO          = 0x3;      //!!!read data, auto transfer   
    uart_printf("Wait read data from sd card.
");

    while(1){                                    //wait FIFO full interrupt
			 n = 100;
       while(n--);		
       if((SDIO1->BUF_CTL & 0x1)){                 //judge which interrupt generation
           uart_printf("Data transmission is completed.
");
           break;
       }
    }
		
    complete = SDIO1->BUF_CTL & 0x1;
    uart_printf("

complete = %d.

",complete);	
//======================================================
//cmd 12
//======================================================
    CMD_Send(12,0);

    SDIO1->MMC_IO = 0x0c;  //auto only response transfer (48bit)
    while(1){
       if(SDIO1->CLR_MMC_INT & 0x1){             //judge which interrupt generation
           uart_printf("Recieve CMD12 response OK.
");
           SDIO1->CLR_MMC_INT = 0x1;   //write 1 clear interrup
           break;
       }
    }
		
    rxdata0 = 0;
    rxdata1 = 0;
    rxdata2 = 0;
    rxdata3 = 0;
    rxdata0 = SDIO1->CMD_BUF3<<24  |SDIO1->CMD_BUF2<<16  |SDIO1->CMD_BUF1<<8  | SDIO1->CMD_BUF0;
    rxdata1 = SDIO1->CMD_BUF4;

    uart_printf("rxdata0 = %x.
",rxdata0);
    uart_printf("rxdata1 = %x.
",rxdata1);

    uart_printf("Read data from data_buf
");
    SDIO1->BUF_CTL   =  0x000;    //read buf

    uart_printf("

");
    for(i = 0;i<128;i++){
			 uart_printf("%x ",SDIO1->DATA_BUF0);
    } 
    uart_printf("

");

    uart_printf("Read data OK
");
		
    n = 100;
    while(n--);		
    uart_printf("Finish.
");
}

参考资料

---

[1]. SD_Physical_Layer_Spec_Version 2.00.pdf
[2]. Simplified_SDIO_Card_Spec_Version 2.00.pdf