实验二十四:SD卡模块

 

驱动SD卡是件容易让人抓狂的事情,驱动SD卡好比SDRAM执行页读写,SD卡虽然不及SDRAM的麻烦要求(时序参数),但是驱动过程却有猥琐操作。除此此外,描述语言只要稍微比较一下C语言,描述语言一定会泪流满面,因为嵌套循环,嵌套判断,或者嵌套函数等都是它的痛。.

史莱姆模块是多模块建模的通病,意指结构能力非常脆弱的模块,暴力的嵌套行为往往会击垮模块的美丽身躯,好让脆弱结构更加脆弱还有惨不忍睹,最终搞垮模块的表达能力。描述语言预想驾驭SD卡,关键的地方就是如何提升模块的结构能力。简单而言,描述语言如何不失自身的美丽,又用自身的方法,去实现嵌套循环或者嵌套函数等近似的内容呢?

低级建模I之际,论结构能力它确实有点勉强,所以SD卡的实验才姗姗来迟。如今病猫已经进化为老虎,而且进化之初的新生儿都会肌饿如心焚,理智也不健全。因为如此,低级建模II才会不停舔着嘴唇,然后渴望新生的第一祭品。遇见SD卡,它仿佛遇见美味的猎物,口水都下流到一塌糊涂。

诸位少年少女们,让我们一起欢呼活祭仪式的开始吧!

二十一世纪的今天,SD卡演化的速度简直迅雷不及掩耳,如今SD卡已经逐渐突破64GB大关。对此,SD卡也存在N多版本,如版本SDV1.×,版本SDV2,或者SDHCV2等,当然未来还会继续演化下去。所谓版本是指建造工艺还有协议,粗略而言,版本SDV1.×是指容量为2GB以下的SD卡,版本SDV2则指容量为2GB~4GB之间的SD卡,版本SDHCV2则是容量为4GB以上的SD卡。

话虽如此,不过实际情况还要根据各个厂商的心情而定,有些厂商的SD卡虽为4GB,但是版本却是SDV1.×,还有厂商的SD卡的虽为 2GB,不过版本却是SDV2,情况尽是让人哭笑不得。此外,版本不会印刷在硬件的表面上,而且不同版本也有不同驱动方法。俗语有云,擒贼先擒卒——凡事从娃娃抓起,所以笔者遵循伟大的智慧,从版本SDV1.×开始动手。

图24.1 SPI模式。

SD卡有SDIO还有SPI两种模式,后者简单又省事,所以SPI模式都是众多懒惰鬼的喜爱。SPI模式一般只用4只引脚,而且主机(FPGA)与从机(SD卡)之间的链接如图24.1所示,至于引脚的聂荣如表24.1所示:

表24.1 SD卡SPI模式的引脚说明。

引脚


说明


SD_CLK


串行时钟,闲置为高


SD_NCS


片选,闲置为高,拉低有效


SD_DI


数据输入,也是主机输出


SD_DOUT


数据输出,也是主机输入

虽然DS1302也有SPI,但是数据线是双向IO,反之SD卡则是一对出入的数据线。话虽如此,它们两者都有乖乖遵守SPI的传输协议,即下降沿设置数据,上升沿锁存数据。

图24.2 写一个字节(主机视角)。

图24.2是主机视角写一个字节的理想时序。主机会利用时钟的下降沿,由高至低发送一个字节的数据。

图24.3 读一个字节(主机视角)。

图24.2是主机视角读一个字节的理想时序。从机会利用时钟的下降沿,由高至低发送一个字节的数据,主机则会利用时钟信号的上升沿,由高至低读取一个字节的数据。

图24.4 同时读写一个字节(主机视角)。

我们知道SD卡有一对读写的数据线,为了节省时间,数据读写是同时发生的。如图24.4所示,那是主机在同时读写的理想时序,读者可以看成是图24.2 还有图24.3的结合体。

对此,Verilog可以这样描述,结果如代码24.1所示:

1.    case(i)
2.        
3.        0,1,2,3,4,5,6,7:
4.        begin
5.             rDI <= iData[ 7-i ];                    
6.            
7.             if( C1 == 0 ) rSCLK <= 1‘b0;
8.            else if( C1 == isHalf ) rSCLK <= 1‘b1;
9.                                
10.            if( C1 == isQuarter ) D1[ 7-i ] <= SD_DOUT;
11.                                
12.            if( C1 == isFull -1 ) begin C1 <= 10‘d0; i <= i + 1‘b1; end
13.            else begin C1 <= C1 + 1‘b1; end
14.        end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

代码24.1

如代码24.1所示,第12~13行表示步骤逗留的时间,其中isFull表示一个时钟周期。第7~8行表示,C1为0拉低时钟,C1为半个周期则拉高时钟。第5行表示,任何时候都更新数据,也可以看成C1为0输出数据。第10行表示,C1为四分之一周期锁存数据。

第3行表示,步骤0~7造就一个字节的读写。还有第5~10行的 D1[7-i] 表示,读写数据由高至低。

好奇的朋友一定会疑惑道,为何第10行的锁存行为不是时钟的半周期(上升沿),而是四分之一呢?原因很单纯,因为数据在这个时候最为有效。

图24.5 写命令(主机视角)。

当然,SD卡不是给足两只骨头就会满足的哈士奇 ... 为此,除了单纯的读写数据意外,SD卡还有所谓的写命令,而写命令则是读写字节的复合体。如图24.5所示,那是主机写命令的理想时序,主机先由高至低发送6个字节的命令。SD卡接受完毕以后,便会反馈一个字节的数据。期间,片选信号必须处于拉低状态。对此,Verilog可以这样表示,结果如代码24.2所示:

1.     case( i )
2.            
3.         0:
4.         begin rCMD <= iAddr; i <= i + 1‘b1; end                      
5.    
6.         1,2,3,4,5,6:
7.         begin T <= rCMD[47:40]; rCMD <= rCMD << 8; i <= FF_Write; Go <= i + 1‘b1; end
8.                         
9.          7:
10.         begin i <= FF_Read; Go <= i + 1‘b1; end
11.                         
12.         8:
13.         if( C2 == 100 ) begin C2 <= 10‘d0; i <= i + 1‘b1; end
14.         else if( D1 != 8‘hff ) begin C2 <= 10‘d0; i <= i + 1‘b1; end
15.         else begin C2 <= C2 + 1‘b1; i <= FF_Read; Go <= i; end
16.                         
17.         ...
18.                                              
19.         12,13,14,15,16,17,18,19: 
20.         begin
21.              rDI <= T[ 19-i ];        
22.              if( C1 == 0 ) rSCLK <= 1‘b0;
23.             else if( C1 == isHalf ) rSCLK <= 1‘b1;
24.                                
25.             if( C1 == isQuarter ) D1[ 19-i ] <= SD_DOUT;
26.                              
27.             if( C1 == isFull -1 ) begin C1 <= 10‘d0; i <= i + 1‘b1; end
28.             else begin C1 <= C1 + 1‘b1; end
29.         end
30.                         
31.        20: 
32.        begin i <= Go; end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

代码24.2

步骤12~20是读写一个字节的伪函数,步骤0准备6个字节的命令,步骤1~6由高至低发送命令,并且进入伪函数。步骤7进入伪函数,并且读取一个字节的反馈数据(注意FF_Write与FF_Read都指向步骤12)。反馈数据一般都是 8’hff 以外的结果,如果不是则重复读取反馈数据100次,如果SD卡反应正常,都会在这100次以内反馈 8’hff以外的结果。

简单而言,如何驱动SD卡就是如何使用相关的命令。版本SDV1.×的SD卡只需4个命令而已,亦即:

(一)CMD0,复位命令;

(二)CMD1,初始化命令;

(三)CMD24,写命令;

(四)CMD17,读命令。

CMD0用来复位SD卡,好让SD卡处于(IDLE)待机状态。CMD1用来初始化SD卡,好让SD卡处于(Transfer)传输状态。CMD24将512字节数据写入指定的地址,CMD17则将512字节数据从指定的地址读出来。

图24.6 CMD0的理想时序图。

图24.6是CMD0的理想时序图,首先在T1延迟1ms给予SD卡热身时间,然后再在T2给予80个准备的时钟。T3之际拉低CS,T4之际则发送命令CMD0 { 8’h40, 32’d0, 8’h95},然后等待SD卡反馈数据R1。如果SD卡成功接收命令CMD0,内容则是8’h01。T5之际拉高CS,T6之际再8个结束时钟。对此,Verilog可以这样描述,结果如代码24.3所示:

1.     case( i )
2.                    
3.        0: // Disable cs, prepare Cmd0
4.        begin rCS <= 1‘b1; D4 <=  {8‘h40, 32‘d0, 8‘h95}; i <= i + 1‘b1; end
5.                        
6.        1: // Wait 1MS for warm up;
7.        if( C1 == T1MS -1) begin C1 <= 16‘d0; i <= i + 1‘b1; end
8.        else begin C1 <= C1 + 1‘b1; end
9.    
10.        2: // Send 80 free clock
11.        if( C1 == 10‘d10 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
12.        else if( iDone ) begin isCall[0] <= 1‘b0; C1 <= C1 + 1‘b1; end
13.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
14.                         
15.        3: // Enable cs
16.        begin rCS <= 1‘b0; i <= i + 1‘b1; end
17.                        
18.        4: // Try 200 time, ready error code.
19.        if( C1 == 10‘d200 ) begin D2 <= CMD0ERR; C1 <= 16‘d0; i <= 4‘d8; end
20.        else if( iDone && iData != 8‘h01) begin isCall[1] <= 1‘b0; C1 <= C1 + 1‘b1; end
21.        else if( iDone && iData == 8‘h01 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end 
22.        else isCall[1] <= 1‘b1;  
23.                         
24.        5: // Disable cs
25.        begin rCS <= 1‘b1 ; i <= i + 1‘b1; end
26.                         
27.        6: // Send free clock
28.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
29.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
30.    
31.        7: // Disable cs, ready OK code
32.        begin D2 <= CMD0OK; i <= i + 1‘b1; end //; 
33.    
34.         8: // Disbale cs, generate done signal
35.        begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
36.                         
37.        9:
38.        begin isDone <= 1‘b0; i <= 4‘d0; end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

代码24.3

我们先假设 isCall[1]执行写命令,isCall[0]则是执行读写字节。如代码24.3所示,步骤0用来准备CMD0命令。步骤1延迟1ms。步骤2执行10次无意义的读写,以示给予80个准备时钟。在此读者稍微注意一下第12行,每当完成一次读写C1便会递增一下,C1递增10次便表示读写执行10次。

步骤3拉低CS,并且步骤4发送命令。步骤4可能会吓坏一群小朋友,不过只要耐心解读,其它它并不可怕。首先执行第22行的写命令,如果反馈数据不为8’h01(第20行),消除isDo便递增C1,然后再返回第22行。如果反馈数据为 8’h01(第21行)

,消除isDo与C1然后继续步骤。如果重复执行100次都失败,D2赋值CMD0的失败信息,消除C1并且i直接步骤8。

步骤5拉低CS,步骤6则给予8个结束时钟。步骤7为D2赋值CMD0的成功信息,步骤8~9拉高CS并且产生完成信号。

图24.7 CMD1的理想时序图。

图24.7是CMD1的理想时序图,T0&T1之际拉低CS并且发送六个字节的命令CMD1 {8’h41,32’d0,8’hff}。SD卡接受命令以后便反馈数据R1——8’h00。T2&T3之际拉高CS并且给予8个结束时钟。Verilog的描述结果如代码24.4所示:

1.     case( i )
2.                    
3.         0: // Enable cs, prepare Cmd1
4.         begin rCS <= 1‘b0; D4 <= { 8‘h41,32‘d0,8‘hff }; i <= i + 1‘b1; end
5.                         
6.         1: // Try 100 times, ready error code.
7.         if( C1 == 10‘d100 ) begin D2 <= CMD1ERR; C1 <= 16‘d0; i <= 4‘d5; end
8.         else if( iDone && iData != 8‘h00) begin isCall[1]<= 1‘b0; C1 <= C1 + 1‘b1; end
9.         else if( iDone && iData == 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end 
10.         else isCall[1] <= 1‘b1;  
11.                         
12.         2: // Disable cs
13.         begin rCS <= 1‘b1; i <= i + 1‘b1; end
14.                         
15.        3: // Send free clock
16.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
17.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
18.                         
19.        4: // Disable cs, ready OK code.
20.        begin D2 <= CMD1OK; i <= i + 1‘b1; end
21.                         
22.        5: // Disable cs, generate done signal
23.        begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
24.                         
25.        6:
26.        begin isDone <= 1‘b0; i <= 4‘d0; end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

代码24.4

如代码24.4所示,步骤0准备命令CMD1。步骤1重复发送CMD1命令100次,直至反馈数据R1为8’h00为止,否则反馈错误信息。步骤2拉高CS,步骤3则给予结束时钟。步骤4反馈成功信息,步骤5~6拉高CS之余也产生完成信号。

好奇的同学一定会觉得疑惑,命令CMD0与命令CMD1同样反馈数据R1,为何前者是8’h01,后者则是8’h00呢?事实上,R1的内容也反应SD卡的当前状态,SD卡有待机状态(IDLE)还有传输状态(Transfer)等两个常见状态。

图24.8 版本V1.×的初始化流程图。

如图24.8所示,那是版本V1.x的初始化流程图。主机先发送CMD0,SD卡接收以后如果反馈R1为8’h01便继续流程,否则重复发送CMD0。主机接着发送CMD1,如果SD卡接收并且反馈R1为8’h00,该结果表示SD卡以从待机状态进入传输状态,余下CMD24还有CMD17才有效。

图24.9 CMD24的理想时序图。

图24.9是CMD24的理想时序图。T0~1之际,主机拉低CS之余,主机也向SD卡发送写命令CMD24,其中Addr 3~Addr 0是写入地址。SD卡接收以后便以反馈数据8’h00表示接收成功。保险起见,主机在T2给足800个准备时钟,如果读者嫌准备时钟给太多,读者可以自行缩小至80。T3之际,主机发送8’hfe以示写512字节开始,T4~T7则是写512字节的过程。T8~T9分别写入两个CRC字节(CRC校验)。

完后,SD卡便会反馈8’h05以示写512字节成功,此刻(T10~11)主机读取并且检测。事后直至SD卡发送8’hff为止,SD卡都处于忙状态。换言之,如果主机在T12成功读取8’hff,结果表示SD卡已经忙完了。T13之际,主机再拉高CS。对此,Verilog可以这样描述,结果如代码24.5所示:

1.    case(i)
2.    
3.         0: // Enable cs, prepare cmd24
4.        begin rCS <= 1‘b0; D4 = { 8‘h58, iAddr, 9‘d0, 8‘hFF }; i <= i + 1‘b1; end
5.                         
6.        1: // Try 100 times, ready error code.
7.        if( C1 == 100 ) begin D2 <= CMD24ERR; C1 <= 16‘d0; i <= 4‘d14; end
8.        else if( iDone && iData != 8‘h00) begin isCall[1] <= 1‘b0; C1 <= C1 + 1‘b1; end
9.        else if( iDone && iData == 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end
10.        else isCall[1] <= 1‘b1;
11.                         
12.        2: // Send 800 free clock 
13.        if( C1 == 100 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
14.        else if( iDone ) begin isCall[0] <= 1‘b0; C1 <= C1 + 1‘b1; end 
15.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hFF; end
16.                         
17.        3: // Send Call byte 0xfe
18.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
19.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hFE; end
20.                                              
21.        4: // Pull up read req.
22.        begin isEn[0] <= 1‘b1; i <= i + 1‘b1; end
23.                         
24.        5: // Pull down read req.
25.        begin isEn[0] <= 1‘b0; i <= i + 1‘b1; end
26.                         
27.        6: // Write byte from fifo
28.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
29.        else begin isCall[0] <= 1‘b1; D1 <= iDataFF; end
30.                         
31.        7: // Repeat 512 times
32.        if( C1 == 10‘d511 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
33.        else begin C1 <= C1 + 1‘b1; i <= 4‘d4; end
34.                         
35.        8: // Write 1st CRC
36.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
37.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
38.                         
39.        9: // Write 2nd CRC
40.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
41.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
42.                         
43.        10: // Read Respond
44.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
45.        else begin isCall[0] <= 1‘b1; end
46.                         
47.        11: // if not 8‘h05, faild and ready error code
48.        if( (iData & 8‘h1F) != 8‘h05 ) begin D2 <= CMD24ERR; i <= 4‘d14; end
49.        else i <= i + 1‘b1;
50.                         
51.        12: // Wait unitl sdcard free
52.        if( iDone && iData == 8‘hff ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
53.        else if( iDone ) begin isCall[0] <= 1‘b0; end
54.        else begin isCall[0] <= 1‘b1; end
55.                         
56.         13: // Disable cs, ready OK code;
57.        begin D2 <= CMD24OK; i <= i + 1‘b1; end
58.                         
59.        14: // Disable cs, generate done signal
60.        begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
61.                         
62.        15:
63.        begin isDone <= 1‘b0; i <= 4‘d0; end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

代码24.5

步骤0拉低CS之余,它也准备写命令CMD24,其中 { iAddr, 9’d0 } 表示地址有512偏移量,内容等价 iAddr << 9。步骤1尝试写命令100次,直至反馈内容为8’h00,否则便准备错误信息。步骤2发送800个准备时钟,如果嫌多可以自行缩小。步骤3写入开始字节 8’hfe。步骤4~5主要是从FIFO取得数据,步骤6则是将数据写入SD卡,步骤7用来控制循环的次数。步骤8~9分别写入两个CRC字节,内容随意。

步骤10读取反馈数据,步骤11则检测反馈数据是否为8’h05,是则继续,不是则准备错误信息,并且跳转步骤14(结束操作)。步骤12不断读取数据,直至读取内容为8’hff位置。步骤13准备成功信息。步骤14~15拉高CS之余也产生完成信号。在此,读者要稍微注意一下,步骤4~7组合起来,类似先执行后判断的 do ... while 循环。

图24.10 CMD17的理想时序图。

图24.10是CMD17的理想时序图。T0~T1之际,主机先拉低CS再发送命令CMD17,其中Addr3~Addr0是指定的读地址,事后SD卡便会反馈数据8’h00以示接收成功。T2之际,主机会不断读取数据,如果读取内容是8’hfe,结果表示SD卡已经准备发送512字节数据。T3~T6之际,主机不断从SD卡那里读取512个字节的数据。T7~T8之际,主机读取两个字节的CRC,然后在T9~10拉高CS之余也给足8个结束时钟。

换之,Verilog的描述结果如代码24.6所示:

1.     case( i )
2.                    
3.        0: // Enable cs, prepare cmd17
4.        begin rCS <= 1‘b0; D4 <= { 8‘h51, iAddr, 9‘d0, 8‘hFF }; i <= i + 1‘b1; end
5.                         
6.        1: // Try 100 times, ready error code
7.        if( C1 == 100 ) begin D2 <= CMD17ERR; C1 <= 16‘d0; i <= 4‘d12; end
8.        else if( iDone && iData != 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= C1 + 1‘b1; end
9.        else if( iDone && iData == 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end
10.        else isCall[1] <= 1‘b1;
11.                         
12.        2: // Wait read ready
13.        if( iDone && iData == 8‘hfe ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
14.        else if( iDone && iData != 8‘hfe ) begin isCall[0] <= 1‘b0; end
15.        else isCall[0] <= 1‘b1;
16.                         
17.        3:  // Read byte
18.        if( iDone ) begin D3 <= iData; isCall[0] <= 1‘b0; i <= i + 1‘b1;  end
19.        else begin isCall[0] <= 1‘b1; end
20.                         
21.        4: // Pull up write req.
22.        begin isEn[1] <= 1‘b1; i <= i + 1‘b1; end
23.                                      
24.        5: // Pull down write req.
25.        begin isEn[1] <= 1‘b0; i <= i + 1‘b1; end 
26.                         
27.        6: // Repeat 512 times
28.        if( C1 == 10‘d511 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
29.        else begin C1 <= C1 + 1‘b1; i <= 4‘d3; end
30.                         
31.        7,8: // Read 1st and 2nd byte CRC
32.        if( iDone ) begin D3 <= iData; isCall[0] <= 1‘b0; i <= i + 1‘b1; end 
33.        else isCall[0] <= 1‘b1;
34.                         
35.        9: // Disable cs
36.        begin rCS <= 1‘b1; i <= i + 1‘b1; end
37.                         
38.        10: // Send free clock
39.        if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end 
40.        else begin isCall[0] <= 1‘b1; D1 <= 8‘hFF; end
41.                         
42.        11: // Ready OK code
43.        begin D2 <= CMD17OK; i <= i + 1‘b1; end
44.                         
45.        12: // Disable cs, generate done signal
46.        begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
47.                         
48.        13:
49.        begin isDone <= 1‘b0; i <= 4‘d0; end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

代码24.6

步骤0拉低CS之余也准备命令CMD17,其中 {iAddr,9’d0} 为 512的偏移量。步骤1重复100次写命令,直至SD卡反馈8’h00,否则准备错误信息,然后跳转步骤12(结束操作)。步骤2不断读取数据,直至读取内容为8’hfe为止。步骤3读取数据,步骤4~5则将数据写入FIFO,步骤6用来控制循环。步骤7~8读取两个字节CRC。步骤9拉高CS,步骤10则给足8个结束时钟。步骤11准备成功信息。步骤12拉高CS之余,也产生完成信号。

上述内容理解完毕以后,我们便可以开始建模了。

图24.11 SD卡基础模块的建模图。

图24.11是SD卡基础模块的建模图,其中内容包括SD卡控制模块,SD卡功能模块,还有两个fifo储存模块。SD卡功能模块的沟通信号Call/Done有两位位宽,其中[1]为写命令,[0]为字节读写。SD卡控制模块的Call/Done位宽有四,表示它支持4个命令,其中[3]为CMD24,[2]为CMD17,[1]为CMD1,[0]为CMD0。两只FIFO储存模块充当写缓存(上)还有读缓存(下),它们被外界调用以外,它们也被SD卡控制模块调用。

sdcard_funcmod.v

图24.12 SD卡功能模块的建模图。

图24.12是SD卡功能模块的建模图,右边是驱动SD卡的顶层信号,左边则是沟通用,还有命令,iData与oData等数据信号。Call/Done位宽有两,其中[1]为写命令,[0]为读写数据。

图24.13 不同状态之间的传输速率。

话题继续之前,请允许笔者作足一些小补充。如图24.13所示,待机状态SD卡为低速状态,速率推荐为100Khz~500Khz之间。保险起见,笔者取为100Khz。反之,传输状态SD卡处于高速状态,速率推荐为2Mhz或者以上。笔者衡量各种因数以后,笔者决定选择10Mhz。丧心病狂的读者当然可以选择10Mhz以上的速率,如果硬件允许的话 ... 据说,100Mhz也没有问题。

1.    module sdcard_funcmod
2.    (
3.         input CLOCK, RESET,
4.         input SD_DOUT,
5.         output SD_CLK,
6.         output SD_DI,
7.         
8.         input [1:0]iCall,
9.         output oDone,
10.         input [47:0]iAddr,
11.         input [7:0]iData,
12.         output [7:0]oData
13.    );

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为出入端声明。

14.         parameter FLCLK = 10‘d500, FLHALF = 10‘d250, FLQUARTER = 10‘d125; //T20US = 100Khz
15.         parameter FHCLK = 10‘d5, FHHALF = 10‘d1, FHQUARTER = 10‘d2; // T1us = 10Mhz
16.         
17.         reg [9:0]isFull,isHalf,isQuarter;
18.         
19.        always @ (  posedge CLOCK or negedge RESET )
20.            if( !RESET )
21.                begin 
22.                      isFull <= FLCLK;
23.                      isHalf <= FLHALF;
24.                      isQuarter <= FLQUARTER;
25.                end    
26.             else if( iAddr[47:40] == 8‘h41 && isDone )
27.                begin
28.                      isFull <= FHCLK;
29.                      isHalf <= FHHALF;
30.                      isQuarter <= FHQUARTER;
31.                 end
32.                      

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

第14~15行是100Khz还有10Mhz的常量声明,F×CLK为一个周期,F×HALF为半个周期,F×QUARTER为四分之一周期,其中×为L表示低速,×为H表示高速。第17~31行是设置速率的周边操作,起始下为低速(第22~24)。不过,当命令CMD1执行成功以后,速率转为为高速(第26~31行)。

33.         parameter FF_Write = 5‘d12, FF_Read = 5‘d12;
34.        
35.         reg [5:0]i,Go;
36.         reg [9:0]C1,C2;
37.         reg [7:0]T,D1;
38.         reg [47:0]rCMD;
39.         reg rSCLK,rDI;
40.         reg isDone;
41.         
42.        always @ ( posedge CLOCK or negedge RESET )
43.             if( !RESET )
44.                  begin
45.                         { i,Go } <= { 6‘d0,6‘d0};
46.                         { C1,C2 } <= { 10‘d0, 10‘d0 };
47.                         { T,D1 } <= { 8‘d0,8‘d0 };
48.                         rCMD <= 48‘d0;
49.                         { rSCLK,rDI } <= 2‘b11;
50.                         isDone <= 1‘b0;
51.                    end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的寄存器声明还有复位操作。其中第33行是伪函数的入口地址。

52.              else if( iCall[1] )  
53.                  case( i )
54.            
55.                         0:
56.                         begin rCMD <= iAddr; i <= i + 1‘b1; end  
57.                         
58.                         1,2,3,4,5,6:
59.                         begin T <= rCMD[47:40]; rCMD <= rCMD << 8; i <= FF_Write; Go <= i + 1‘b1; end
60.                         
61.                         7:
62.                         begin i <= FF_Read; Go <= i + 1‘b1; end
63.                         
64.                         8:
65.                         if( C2 == 100 ) begin C2 <= 10‘d0; i <= i + 1‘b1; end
66.                         else if( D1 != 8‘hff ) begin C2 <= 10‘d0; i <= i + 1‘b1; end
67.                         else begin C2 <= C2 + 1‘b1; i <= FF_Read; Go <= i; end
68.                         
69.                         9:
70.                         begin isDone <= 1‘b1; i <= i + 1‘b1; end
71.                         
72.                         10:
73.                         begin isDone <= 1‘b0; i <= 6‘d0; end
74.                         
75.                         /******************************/
76.                         
77.                         12,13,14,15,16,17,18,19: 
78.                         begin
79.                              rDI <= T[ 19-i ];
80.                                
81.                              if( C1 == 0 ) rSCLK <= 1‘b0;
82.                              else if( C1 == isHalf ) rSCLK <= 1‘b1;
83.                                
84.                              if( C1 == isQuarter ) D1[ 19-i ] <= SD_DOUT;
85.                              
86.                              if( C1 == isFull -1 ) begin C1 <= 10‘d0; i <= i + 1‘b1; end
87.                              else begin C1 <= C1 + 1‘b1; end
88.                         end
89.                         
90.                         20: 
91.                         begin i <= Go; end
92.            
93.                endcase    

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为写命令。

94.              else if( iCall[0] ) 
95.                  case( i )
96.                        
97.                         0,1,2,3,4,5,6,7:
98.                         begin
99.                              rDI <= iData[ 7-i ];
100.                                
101.                              if( C1 == 0 ) rSCLK <= 1‘b0;
102.                              else if( C1 == isHalf ) rSCLK <= 1‘b1;
103.                                
104.                              if( C1 == isQuarter ) D1[ 7-i ] <= SD_DOUT;
105.                                
106.                              if( C1 == isFull -1 ) begin C1 <= 10‘d0; i <= i + 1‘b1; end
107.                              else begin C1 <= C1 + 1‘b1; end
108.                         end
109.                         
110.                         8:
111.                         begin isDone <= 1‘b1; i <= i + 1‘b1; end
112.                         
113.                         9:
114.                         begin isDone <= 1‘b0; i <= 6‘d0; end
115.                    
116.                    endcase    
117.        

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为读写一个字节。

118.         assign SD_CLK = rSCLK;     
119.         assign SD_DI = rDI;     
120.         assign oDone = isDone;
121.         assign oData = D1;
122.    
123.    endmodule

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的输出驱动。

fifo_savemod.v

图24.14 FIFO储存模块的建模图。

图24.14是大伙看烂的FIFO储存模块,具体内容让我们来看代码吧。

1.    module fifo_savemod
2.    (
3.         input CLOCK, RESET, 
4.         input [1:0]iEn,
5.         input [7:0]iData,
6.         output [7:0]oData,
7.         output [1:0]oTag
8.    );
9.        initial begin
10.             for( C1 = 0; C1 < 1024; C1 = C1 + 1‘b1 )
11.                  begin  RAM[ C1 ] <= 8‘d0; end    
12.         end
13.        
14.        reg [7:0] RAM [1023:0]; 
15.        reg [10:0] C1 = 11‘d0,C2 = 11‘d0; // N+1
16.         reg [7:0]D1;
17.                  
18.       always @ ( posedge CLOCK or negedge RESET )
19.            if( !RESET )
20.                 begin
21.                      C1 <= 11‘d0;
22.                  end
23.           else if( iEn[1] ) 
24.                 begin   
25.                    RAM[ C1[9:0] ] <= iData; 
26.                     C1 <= C1 + 1‘b1; 
27.                  end
28.                  
29.        always @ ( posedge CLOCK or negedge RESET )
30.            if( !RESET )
31.                 begin
32.                        C2 <= 11‘d0;
33.                        D1 <= 8‘d0;
34.                  end
35.             else if( iEn[0] )
36.                    begin 
37.                         D1 <= RAM[ C2[9:0] ]; 
38.                         C2 <= C2 + 1‘b1; 
39.                    end
40.        
41.          assign oData = D1;                
42.          assign oTag[1] = ( C1[10]^C2[10] & C1[9:0] == C2[9:0] ); // Full Left
43.           assign oTag[0] = ( C1 == C2 ); // Empty Right
44.    
45.    endmodule

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

由于数据缓冲对象不是SDRAM,所以第41行的oData由D1驱动而不是RAM直接驱动。余下内容,读者自己看着办吧。

sdcard_ctrlmod.v

图24.15 SD卡控制模块的建模图。

图24.15是SD卡控制模块的建模图,它好比一只刺猬,全身上下都长满箭头,让人看见也怕怕。右边是调用功能模块的信号群,上下则是调用储存模块的信号群。左边则是被外界调用的信号群,其中顶层信号SD_NCS是SD卡的片选信号。此外,Call/Done位宽有4,表示该模块支持4个命令,[3]为CMD24, [2]为CMD17, [1]为CMD1,[0]为CMD0。至于oTag则是用来反馈命令的执行状态。

1.    module sdcard_ctrlmod
2.    (
3.         input CLOCK, RESET,
4.         output SD_NCS,
5.         
6.         input [3:0]iCall,
7.         output oDone,
8.         input [22:0]iAddr,
9.         output [7:0]oTag,
10.         
11.         output [1:0]oEn, // [1] Write [0] Read
12.         input [7:0]iDataFF,
13.         output [7:0]oDataFF,
14.         
15.         output [1:0]oCall, 
16.         input iDone,
17.         output [47:0]oAddr,
18.         input [7:0]iData,
19.         output [7:0]oData
20.    );    

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的出入端声明,第6~9行是外界调用的信号,第11~13行是调用FIFO的信号,第15~19则是调用功能模块的信号。

21.         parameter CMD0ERR = 8‘hA1, CMD0OK = 8‘hA2, CMD1ERR = 8‘hA3, CMD1OK = 8‘hA4; 
22.         parameter CMD24ERR = 8‘hA5, CMD24OK = 8‘hA6, CMD17ERR = 8‘hA7, CMD17OK = 8‘hA8;
23.         parameter T1MS = 16‘d10;
24.        

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为各个命令的成功信息还有失败信息之间的常量声明。

25.         reg [3:0]i;
26.         reg [15:0]C1;
27.         reg [7:0]D1,D2,D3;  // D1 WrData, D2 FbData, D3 RdData
28.         reg [47:0]D4;       // D4 Cmd
29.         reg [1:0]isCall,isEn;
30.         reg rCS;
31.         reg isDone;
32.         
33.        always @ ( posedge CLOCK or negedge RESET )
34.             if( !RESET )
35.                  begin
36.                        i <= 4‘d0;
37.                         C1 <= 16‘d0;
38.                         { D1,D2,D3 } <= { 8‘d0, 8‘d0, 8‘d0 };
39.                         D4 <= 48‘d0;
40.                         { isCall, isEn } <= { 2‘d0,2‘d0 }; 
41.                         rCS <= 1‘b1;
42.                    end

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的寄存器声明还有复位操作,其中D1暂存写数据,D2暂存反馈信息,D3暂存读数据,D4暂存命令,isDo控制写命令还有字节读写,isEn控制FIFO的读写。

所有寄存器的复位值为0,rCS除外。

43.            else if( iCall[3] ) // cmd24
44.                  case( i )
45.                    
46.                         0: // Enable cs, prepare cmd24
47.                         begin rCS <= 1‘b0; D4 = { 8‘h58, iAddr, 9‘d0, 8‘hFF }; i <= i + 1‘b1; end
48.                         
49.                         1: // Try 100 times, ready error code.
50.                         if( C1 == 100 ) begin D2 <= CMD24ERR; C1 <= 16‘d0; i <= 4‘d14; end
51.                         else if( iDone && iData != 8‘h00) begin isCall[1] <= 1‘b0; C1 <= C1 + 1‘b1; end
52.                         else if( iDone && iData == 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end
53.                         else isCall[1] <= 1‘b1;
54.                         
55.                         2: // Send 800 free clock 
56.                         if( C1 == 100 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
57.                         else if( iDone ) begin isCall[0] <= 1‘b0; C1 <= C1 + 1‘b1; end 
58.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hFF; end
59.                         
60.                         3: // Send Call byte 0xfe
61.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
62.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hFE; end
63.                         
64.                         /*****************/
65.                         
66.                         4: // Pull up read req.
67.                         begin isEn[0] <= 1‘b1; i <= i + 1‘b1; end
68.                         
69.                         5: // Pull down read req.
70.                         begin isEn[0] <= 1‘b0; i <= i + 1‘b1; end
71.                         
72.                         6: // Write byte from fifo
73.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
74.                         else begin isCall[0] <= 1‘b1; D1 <= iDataFF; end
75.                         
76.                         7: // Repeat 512 times
77.                         if( C1 == 10‘d511 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
78.                         else begin C1 <= C1 + 1‘b1; i <= 4‘d4; end
79.                         
80.                          /*****************/
81.                         
82.                         8: // Write 1st CRC
83.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
84.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
85.                         
86.                         9: // Write 2nd CRC
87.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
88.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
89.                         
90.                         10: // Read Respond
91.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
92.                         else begin isCall[0] <= 1‘b1; end
93.                         
94.                         11: // if not 8‘h05, faild and ready error code
95.                         if( (iData & 8‘h1F) != 8‘h05 ) begin D2 <= CMD24ERR; i <= 4‘d14; end
96.                         else i <= i + 1‘b1;
97.                         
98.                         12: // Wait unitl sdcard free
99.                         if( iDone && iData == 8‘hff ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
100.                         else if( iDone ) begin isCall[0] <= 1‘b0; end
101.                         else begin isCall[0] <= 1‘b1; end
102.                         
103.                         /*****************/
104.                         
105.                         13: // Disable cs, ready OK code;
106.                         begin D2 <= CMD24OK; i <= i + 1‘b1; end
107.                         
108.                         14: // Disable cs, generate done signal
109.                         begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
110.                         
111.                         15:
112.                         begin isDone <= 1‘b0; i <= 4‘d0; end
113.                    
114.                    endcase

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为命令CMD24。

115.            else if( iCall[2] ) // cmd17
116.                  case( i )
117.                    
118.                        0: // Enable cs, prepare cmd17
119.                         begin rCS <= 1‘b0; D4 <= { 8‘h51, iAddr, 9‘d0, 8‘hFF }; i <= i + 1‘b1; end
120.                         
121.                         1: // Try 100 times, ready error code
122.                         if( C1 == 100 ) begin D2 <= CMD17ERR; C1 <= 16‘d0; i <= 4‘d12; end
123.                         else if( iDone && iData != 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= C1 + 1‘b1; end
124.                         else if( iDone && iData == 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end
125.                         else isCall[1] <= 1‘b1;
126.                         
127.                         2: // Wait read ready
128.                         if( iDone && iData == 8‘hfe ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
129.                         else if( iDone && iData != 8‘hfe ) begin isCall[0] <= 1‘b0; end
130.                         else isCall[0] <= 1‘b1;
131.                         
132.                         /********/
133.                         
134.                         3:  // Read byte
135.                         if( iDone ) begin D3 <= iData; isCall[0] <= 1‘b0; i <= i + 1‘b1;  end
136.                         else begin isCall[0] <= 1‘b1; end
137.                         
138.                         4: // Pull up write req.
139.                         begin isEn[1] <= 1‘b1; i <= i + 1‘b1; end
140.                                              
141.                         5: // Pull down write req.
142.                         begin isEn[1] <= 1‘b0; i <= i + 1‘b1; end 
143.                         
144.                         6: // Repeat 512 times
145.                         if( C1 == 10‘d511 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
146.                         else begin C1 <= C1 + 1‘b1; i <= 4‘d3; end
147.                         
148.                         /********/
149.                         
150.                         7,8: // Read 1st and 2nd byte CRC
151.                         if( iDone ) begin D3 <= iData; isCall[0] <= 1‘b0; i <= i + 1‘b1; end 
152.                         else isCall[0] <= 1‘b1;
153.                         
154.                         9: // Disable cs
155.                         begin rCS <= 1‘b1; i <= i + 1‘b1; end
156.                         
157.                         10: // Send free clock
158.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end 
159.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hFF; end
160.                         
161.                         11: // Ready OK code
162.                         begin D2 <= CMD17OK; i <= i + 1‘b1; end
163.                         
164.                         12: // Disable cs, generate done signal
165.                         begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
166.                         
167.                         13:
168.                         begin isDone <= 1‘b0; i <= 4‘d0; end
169.                         
170.                    endcase    

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为命令CMD17。

171.             else if( iCall[1] ) // cmd1
172.                  case( i )
173.                    
174.                         0: // Enable cs, prepare Cmd1
175.                         begin rCS <= 1‘b0; D4 <= { 8‘h41,32‘d0,8‘hff }; i <= i + 1‘b1; end
176.                         
177.                         1: // Try 100 times, ready error code.
178.                         if( C1 == 10‘d100 ) begin D2 <= CMD1ERR; C1 <= 16‘d0; i <= 4‘d5; end
179.                         else if( iDone && iData != 8‘h00) begin isCall[1]<= 1‘b0; C1 <= C1 + 1‘b1; end
180.                         else if( iDone && iData == 8‘h00 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end 
181.                         else isCall[1] <= 1‘b1;  
182.                         
183.                         2: // Disable cs
184.                         begin rCS <= 1‘b1; i <= i + 1‘b1; end
185.                         
186.                         3: // Send free clock
187.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
188.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
189.                         
190.                         /******************/
191.                         
192.                         4: // Disable cs, ready OK code.
193.                         begin D2 <= CMD1OK; i <= i + 1‘b1; end
194.                         
195.                         5: // Disable cs, generate done signal
196.                         begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
197.                         
198.                         6:
199.                         begin isDone <= 1‘b0; i <= 4‘d0; end
200.                         
201.                    endcase

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为命令CMD1。

202.            else if( iCall[0] ) // cmd0
203.                  case( i )
204.                    
205.                         0: // Disable cs, prepare Cmd0
206.                         begin rCS <= 1‘b1; D4 <= {8‘h40, 32‘d0, 8‘h95}; i <= i + 1‘b1; end
207.                        
208.                         1: // Wait 1MS for warm up;
209.                         if( C1 == T1MS -1) begin C1 <= 16‘d0; i <= i + 1‘b1; end
210.                         else begin C1 <= C1 + 1‘b1; end
211.    
212.                         2: // Send 80 free clock
213.                         if( C1 == 10‘d10 ) begin C1 <= 16‘d0; i <= i + 1‘b1; end
214.                         else if( iDone ) begin isCall[0] <= 1‘b0; C1 <= C1 + 1‘b1; end
215.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
216.                         
217.                         3: // Enable cs
218.                         begin rCS <= 1‘b0; i <= i + 1‘b1; end
219.                        
220.                         4: // Try 200 time, ready error code.
221.                         if( C1 == 10‘d200 ) begin D2 <= CMD0ERR; C1 <= 16‘d0; i <= 4‘d8; end
222.                         else if( iDone && iData != 8‘h01) begin isCall[1] <= 1‘b0; C1 <= C1 + 1‘b1; end
223.                         else if( iDone && iData == 8‘h01 ) begin isCall[1] <= 1‘b0; C1 <= 16‘d0; i <= i + 1‘b1; end 
224.                         else isCall[1] <= 1‘b1;  
225.                         
226.                         5: // Disable cs
227.                         begin rCS <= 1‘b1 ; i <= i + 1‘b1; end
228.                         
229.                         6: // Send free clock
230.                         if( iDone ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
231.                         else begin isCall[0] <= 1‘b1; D1 <= 8‘hff; end
232.                         
233.                         7: // Disable cs, ready OK code
234.                         begin D2 <= CMD0OK; i <= i + 1‘b1; end 
235.                         
236.                         8: // Disbale cs, generate done signal
237.                         begin rCS <= 1‘b1; isDone <= 1‘b1; i <= i + 1‘b1; end
238.                         
239.                         9:
240.                         begin isDone <= 1‘b0; i <= 4‘d0; end
241.                    
242.                    endcase
243.        

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为命令CMD0。

244.        assign SD_NCS = rCS;
245.        assign oDone = isDone;
246.        assign oTag = D2;
247.        assign oEn = isEn; 
248.        assign oDataFF = D3;
249.        assign oCall = isCall;
250.        assign oAddr = D4;
251.        assign oData = D1;
252.    
253.    endmodule

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的输出驱动声明。

sdcard_basemod.v

该模块为SD卡基础模块,连线部署请参考图24.11。

1.    module sdcard_basemod
2.    (
3.         input CLOCK, RESET,
4.         input SD_DOUT,
5.         output SD_CLK,
6.         output SD_DI,
7.         output SD_NCS,  
8.         
9.         input [3:0]iCall,
10.         output oDone,
11.         input [22:0]iAddr,
12.         output [7:0]oTag,
13.         
14.         input [1:0]iEn,
15.         input [7:0]iData,
16.         output [7:0]oData
17.    ); 
18.         wire [1:0]EnU1;
19.         wire [7:0]DataFFU1;
20.         wire [1:0]CallU1;
21.         wire [47:0]AddrU1;
22.         wire [7:0]DataU1;
23.        
24.        sdcard_ctrlmod U1
25.         (
26.             .CLOCK( CLOCK ),
27.             .RESET( RESET ),
28.             .SD_NCS(  SD_NCS ),     // > top
29.             .iCall( iCall ),                // < top
30.             .oDone( oDone ),              // < top
31.             .iAddr( iAddr ),              // < top
32.             .oTag( oTag ),            // > top
33.             .oEn( EnU1 ),             // > U2 & U3
34.             .iDataFF( DataFFU2 ),         // < U2 
35.             .oDataFF( DataFFU1 ),         // > U3
36.             .oCall( CallU1 ),             // > U4 
37.             .iDone( DoneU4 ),             // < U4
38.             .oAddr( AddrU1 ),           // > U4
39.             .iData( DataU4 ),             // < U4
40.             .oData( DataU1 )             // > U4
41.         );
42.         
43.         wire [7:0]DataFFU2;
44.         
45.        fifo_savemod U2
46.        (
47.            .CLOCK ( CLOCK ),
48.            .RESET( RESET ),
49.            .iEn ( {iEn[1],EnU1[0]} ),      // < top & U1
50.            .iData ( iData ),               // < top
51.            .oData ( DataFFU2 ),            // > U1
52.            .oTag ()
53.        );
54.        
55.        fifo_savemod U3
56.        (
57.            .CLOCK ( CLOCK ),
58.            .RESET( RESET ),
59.            .iEn ( {EnU1[1],iEn[0]} ),  // < top & U1
60.            .iData ( DataFFU1 ),        // < U1
61.            .oData ( oData ),           // > top
62.            .oTag ()
63.        );
64.        
65.        wire DoneU4;
66.        wire [7:0]DataU4;
67.        
68.         sdcard_funcmod U4
69.         (
70.              .CLOCK( CLOCK ), 
71.              .RESET( RESET ),
72.              .SD_CLK( SD_CLK ),       // > top
73.              .SD_DOUT( SD_DOUT ),  // < top
74.              .SD_DI( SD_DI ),            // > top
75.              .iCall( CallU1 ),           // < U1
76.              .oDone( DoneU4 ),            // > U1
77.              .iAddr( AddrU1 ),          // < U1
78.              .iData( DataU1 ),            // < U1
79.              .oData( DataU4 )             // > U1
80.         );
81.         
82.    endmodule

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容,读者自己看着办吧,笔者犯懒了。

sdcard_demo.v

图24.16 实验二十四的建模图。

图24.16是实验二十四的建模图,右边是SD卡基础模块,右边则是调用该模块的核心程序。核心程序先初始化SD卡,期间也将反馈信息经由TXD发送出去。再者,它将512个字节写入SD卡,又从中读出,然后经由TXD发送出去。具体内容让我们来看代码吧:

1.    module sdcard_demo
2.    (
3.         input CLOCK,RESET,
4.         output SD_NCS, 
5.         output SD_CLK,
6.         input SD_DOUT,
7.         output SD_DI,
8.         output TXD
9.    );

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的出入端声明。

10.        wire DoneU1;
11.        wire [7:0]TagU1;
12.        wire [7:0]DataU1;
13.    
14.        sdcard_basemod U1
15.         (
16.              .CLOCK( CLOCK ), 
17.              .RESET( RESET ),
18.              .SD_DOUT( SD_DOUT ),
19.              .SD_CLK( SD_CLK ),
20.              .SD_DI( SD_DI ),
21.              .SD_NCS( SD_NCS ), 
22.              .iCall( isCall ),
23.              .oDone( DoneU1 ),
24.              .iAddr( D1 ),
25.              .oTag( TagU1 ),
26.              /**********/
27.              .iEn( isEn ),
28.              .iData( D2 ),
29.              .oData( DataU1 )
30.         );
31.         

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为SD卡基础模块实例化,其中isCall驱动iCall,D1驱动iAddr,isEn驱动iEn,D2驱动iData。

32.        parameter B115K2 = 11‘d434, TXFUNC = 6‘d16;
33.         
34.         reg [5:0]i,Go;
35.         reg [10:0]C1,C2;
36.         reg [22:0]D1;
37.         reg [7:0]D2;
38.         reg [10:0]T;
39.         reg [3:0]isCall;
40.         reg [1:0]isEn;
41.         reg rTXD;
42.         
43.         always @ ( posedge CLOCK or negedge RESET )
44.             if( !RESET )
45.                  begin
46.                          { i,Go } <= { 6‘d0,6‘d0 };
47.                         { C1,C2 } <= { 11‘d0,11‘d0 };
48.                         { D1,D2,T } <= { 23‘d0,8‘d0,11‘d0 };
49.                         { isCall,isEn } <= { 4‘d0,2‘d0 };
50.                         rTXD <= 1‘b1;
51.                  end
52.                else

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

以上内容为相关的寄存器声明还有复位操作,当然也包括波特率的常量声明还有伪函数入口。

53.                    case( i )
54.                         
55.                          0: // cmd0
56.                         if( DoneU1 ) begin isCall[0] <= 1‘b0; i <= i + 1‘b1; end
57.                         else begin isCall[0] <= 1‘b1; end
58.                         
59.                         1:
60.                         begin T <= { 2‘b11, TagU1, 1‘b0 }; i <= TXFUNC; Go <= i + 1‘b1; end
61.                         
62.                         /********************/
63.                         

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤0执行CMD0,然后步骤1反馈执行结果。

64.                         2: // cmd1
65.                         if( DoneU1 ) begin isCall[1] <= 1‘b0; i <= i + 1‘b1; end
66.                         else begin isCall[1] <= 1‘b1; end
67.                         
68.                         3:
69.                         begin T <= { 2‘b11, TagU1, 1‘b0 }; i <= TXFUNC; Go <= i + 1‘b1; end
70.                         
71.                         /*********************/
72.                         

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤2执行CMD1,然后步骤3反馈执行结果。

73.                         4: // write data to fifo
74.                         begin isEn[1] <= 1‘b1; i <= i + 1‘b1; end
75.                         
76.                         5:
77.                         begin isEn[1] <= 1‘b0; i <= i + 1‘b1; end
78.                         
79.                         6:
80.                         if( C2 == 511 ) begin C2 <= 11‘d0; i <= i + 1‘b1; end
81.                         else begin D2 <= D2 + 1‘b1; C2 <= C2 + 1‘b1; i <= 6‘d4; end
82.                         
83.                        /**************/    
84.                         

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤4~6将数据00~FF写入FIFO两遍。

85.                         7:  // cmd24
86.                         if( DoneU1 ) begin isCall[3] <= 1‘b0; i <= i + 1‘b1; end
87.                         else begin isCall[3] <= 1‘b1; D1 <= 23‘d0; end
88.                         
89.                         8:
90.                         begin T <= { 2‘b11, TagU1, 1‘b0 }; i <= TXFUNC; Go <= i + 1‘b1; end
91.                         
92.                         /***************/
93.                         

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤7执行CMD24,写入地址为23’d0。步骤8反馈执行结果。

94.                         9: // cmd17
95.                         if( DoneU1 ) begin isCall[2] <= 1‘b0; i <= i + 1‘b1; end
96.                         else begin isCall[2] <= 1‘b1; D1 <= 23‘d0; end
97.                         
98.                         10:
99.                         begin T <= { 2‘b11, TagU1, 1‘b0 }; i <= TXFUNC; Go <= i + 1‘b1; end
100.                         
101.                         /****************/
102.                         

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤9执行CMD17,步骤10则反馈执行结果。

103.                         11: // Read data from fifo
104.                         begin isEn[0] <= 1‘b1; i <= i + 1‘b1; end
105.                         
106.                         12:
107.                         begin isEn[0] <= 1‘b0; i <= i + 1‘b1; end
108.                         
109.                         13:
110.                         begin T <= { 2‘b11, DataU1, 1‘b0 }; i <= TXFUNC; Go <= i + 1‘b1; end
111.                         
112.                         14:
113.                         if( C2 == 511 ) begin C2 <= 11‘d0; i <= i + 1‘b1; end
114.                         else begin C2 <= C2 + 1‘b1; i <= 6‘d11; end
115.                         
116.                         15: 
117.                         i <= i;
118.                         
119.                         /****************/
120.                        

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤11~14从FIFO哪里读出数据512次,然后再经由TXD发送出去。

121.                         16,17,18,19,20,21,22,23,24,25,26:
122.                         if( C1 == B115K2 -1 ) begin C1 <= 11‘d0; i <= i + 1‘b1; end
123.                         else begin rTXD <= T[i - 16]; C1 <= C1 + 1‘b1; end
124.                         
125.                         27:
126.                         i <= Go;
127.                     
128.                     endcase
129.                     
130.        assign TXD = rTXD;
131.    
132.    endmodule

.csharpcode, .csharpcode pre
{
font-size: small;
color: black;
font-family: consolas, "Courier New", courier, monospace;
background-color: #ffffff;
/*white-space: pre;*/
}
.csharpcode pre { margin: 0em; }
.csharpcode .rem { color: #008000; }
.csharpcode .kwrd { color: #0000ff; }
.csharpcode .str { color: #006080; }
.csharpcode .op { color: #0000c0; }
.csharpcode .preproc { color: #cc6633; }
.csharpcode .asp { background-color: #ffff00; }
.csharpcode .html { color: #800000; }
.csharpcode .attr { color: #ff0000; }
.csharpcode .alt
{
background-color: #f4f4f4;
width: 100%;
margin: 0em;
}
.csharpcode .lnum { color: #606060; }

步骤16~27是发送一帧数据的伪函数。综合完毕,插入版本V1.×的SD卡,例如笔者手上 IProc制,容量为256MB的SD卡,然后下载程序。演示过程如下:

A2 // CMD0 执行成功

A4 // CMD1 执行成功

A6 // CMD24 执行成功

A8 // CMD17 执行成功

00~FF // 读出数据 0~255

00~FF // 读出数据 256~511

图24.17 SD卡的内容。

为了验证SD卡是否成功写入 00~FF 两遍,笔者稍微瞧瞧 SD卡的内容 ... 如图24.17所示,地址0x00~0xF0(0~255)的内容是 00~FF,地址0x0100~0x01F0(256~511)的内容也是 00~FF。

细节一:完整的个体模块

虽然本实验的SD卡基础模块已经就绪,不过SD卡的前提条件必须是版本SDV1.×,还有健康的硬件。嘛,SD卡基础模块傻是傻了一点,不过它还可以继续扩展。

时间: 05-20

实验二十四:SD卡模块的相关文章

第三百二十四节,web爬虫,scrapy模块介绍与使用

第三百二十四节,web爬虫,scrapy模块介绍与使用 Scrapy是一个为了爬取网站数据,提取结构性数据而编写的应用框架. 其可以应用在数据挖掘,信息处理或存储历史数据等一系列的程序中.其最初是为了页面抓取 (更确切来说, 网络抓取 )所设计的, 也可以应用在获取API所返回的数据(例如 Amazon Associates Web Services ) 或者通用的网络爬虫.Scrapy用途广泛,可以用于数据挖掘.监测和自动化测试. Scrapy 使用了 Twisted异步网络库来处理网络通讯.

嵌入式Linux裸机开发(十)——SD卡启动

嵌入式Linux裸机开发(十)--SD卡启动 存储设备分类: 磁存储设备:软盘.硬盘.光盘.CD.磁带 Flash:NandFlash.NorFlash 缺点:时序复杂,无坏块处理机制,接口不统一 NandFlash:MLC(可靠性差,容量大).SLC(可靠性高.容量小) 扩展卡式Flash:SD卡.MMC卡.MicroSD(TF卡) 内部为NnadFlash存储颗粒,外部封装了接口,接口标准统一.通用. 缺点:频繁使用导致卡槽接触不可靠 iNand.MoviNand.eSSD: 内部为Nand

全栈JavaScript之路( 二十四 )DOM2、DOM3, 不涉及XML命名空间的扩展

(一)DocumentType 类型的变化新增三个属性: publicId,systemId,internalSubset(内部子集) <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd" [<!ELEMENT name (#PCDATA)>] > 通过, document.doc

QT开发(二十四)——QT文件操作

QT开发(二十四)--QT文件操作 一.QT文件操作简介 QT中的IO操作通过统一的接口简化了文件与外部设备的操作方式,QT中文件被当作一种特殊的外部设备,文件操作与外部设备操作相同. 1.IO操作的主要函数接口 打开设备:bool open(OpenMode mode) 读取数据:QByteArray read(qint64 maxSize) 写入数据:qint64 write(const QByteArray & byteArray) 关闭设备:void close() IO操作的本质是连续

从零开始学android&lt;android事件的处理方式.二十四.&gt;

在android中一共有 多种事件,每种事件都有自己相对应的处理机制 如以下几种 1 单击事件 View.OnClickListener public abstract void onClick (View v) 单击组件时触发 2 单击事件 View.OnLongClickListener public abstract boolean onLongClick (View v) 长按组件时触发 3 键盘事件 View.OnKeyListener public abstract boolean

攻城狮在路上(叁)Linux(二十四)--- linux设置开机挂载及镜像文件挂载

虽然可以手动进行文件系统的挂载,但是每次都手动挂载就会很麻烦,开机挂载的目的就是实现文件系统的自动挂载. 一.开机挂载:/etc/fstab及/etc/mtab 主要是通过修改/etc/fstab文件的配置来实现. fstab是开机时的设置,实际文件系统的挂载是记录到/etc/mtab和/proc/mounts这两个文件中. 1.系统挂载的限制: A.根目录/必须挂载,而且一定是最先挂载的,要先于其他mount point. B.其他挂载点必须为已新建的目录,可以任意指定. C.所有挂载点在同一

马哥学习笔记二十四——分布式复制快设备drbd

DRBD: 主从 primary: 可执行读.写操作 secondary: 文件系统不能挂载 DRBD: dual primay, 双主(基于集群文件系统的高可用集群) 磁盘调度器:合并读请求,合并写请求: Procotol:drbd数据同步协议 A: Async, 异步  数据发送到本机tcp/ip协议栈 B:semi sync, 半同步  数据发送到对方tcp/ip协议 C:sync, 同步  数据到达对方存储设备 DRBD Source: DRBD资源 资源名称:可以是除了空白字符外的任意

【管理心得之二十四】成功乃失败之母

场景再现 ======================= Boss:侯さん,这次项目做得不错. 一,得到日本客户的高评, 二,争取到了新客户 三,新领域尝试是正确的 所谓是"一箭三雕",年底一定给你们团队一个嘉奖. 侯さん:哪里哪里,若不是您在背后的大力支持,"巧妇难为无米之炊"哪里有今天的成果. Boss:切忌"成功是失败之母",你去忙吧. 侯さん:嗯------? {侯さん走出办公室,心想---..} "这Boss有点意思,耳熟能详

winform学习日志(二十四)----------datetime和timer的使用(小小幻灯片)

一:展示图片 每秒换一次图片,一共六十张图片,00-59 二:代码 a,设计代码 namespace timePicture { partial class Form1 { /// <summary> /// 必需的设计器变量. /// </summary> private System.ComponentModel.IContainer components = null; /// <summary> /// 清理所有正在使用的资源. /// </summary