(转)CortexM3 (NXP LPC1788)之IIS应用UDA1380进行音频数据播放

(转)CortexM3 (NXP LPC1788)之IIS应用UDA1380进行音频数据播放
LPC1788发送到I2S总线上的音频数据要通过音频解码芯片才能输出模拟音频信号。开发板上使用的是UDA1380，对它的寄存器的配置可以通过L3总线或者I2C总线进行，这里使用I2C总线进行控制，对于I2C总线的操作可以参考之前I2C的介绍。UDA1380的寄存器主要分成3类，系统控制、插值滤波(interpolation filter)、抽取滤波(decimator filter)。插值滤波和DAC转换有关，用于控制控制声音的输出参数。抽取滤波和ADC有关，用于控制对音频的采样。寄存器的地址和功能如图1所示。

图1：UDA1380寄存器地址和功能

根据图1的红色标记中的内容，可以知道两个滤波器的正常使用需要一个128fs的clock，这个时钟可以通过SYSCLK引脚或者WSI的信号获得。在硬件连接上，通过将LPC1788的MCLK输出的时钟，连接到UDA1380的SYSCLK引脚。因此，我们需要配置I2S的发送模式控制寄存器I2STXMODE，使能TX_REF在MCLK输出，使UDA1380内部产生一个滤波器需要的时钟。

程序中我们通过I2S发送一段音频数据，该数据是我从WAV格式的文件中去掉WAV头格式后得到的一个纯音频数据数组。该WAV音频为16位双通道采样频率为44.1KHZ。LPC1788将该数组发送到I2S总线，UDA1380读取该数据进行声音的输出。程序如下
[cpp] view plain copy print ?
1. #include "i2c.h"
2. #include "audio.h"
4. #define rI2SDAO (*(volatile unsigned *)(0x400A8000))
5. #define rI2STXFIFO (*(volatile unsigned *)(0x400A8008))
6. #define rI2STXRATE (*(volatile unsigned *)(0x400A8020))
7. #define rI2STXBITRATE (*(volatile unsigned *)(0x400A8028))
8. #define rI2STXMODE (*(volatile unsigned *)(0x400A8030))
10. #define rI2SDMA1 (*(volatile unsigned *)(0x400A8014))
11. #define rI2SDMA2 (*(volatile unsigned *)(0x400A8018))
12. #define rI2SSTATE (*(volatile unsigned *)(0x400A8010))
13. #define rI2SIRQ (*(volatile unsigned *)(0x400A801C))
15. #define rI2SDAI (*(volatile unsigned *)(0x400A8004))
16. #define rI2SRXFIFO (*(volatile unsigned *)(0x400A800C))
17. #define rI2SRXRATE (*(volatile unsigned *)(0x400A8024))
18. #define rI2SRXBITRATE (*(volatile unsigned *)(0x400A802C))
19. #define rI2SRXMODE (*(volatile unsigned *)(0x400A8034))
21. #define rIOCON_P0_07 (*(volatile unsigned *)(0x4002C01C))
22. #define rIOCON_P0_08 (*(volatile unsigned *)(0x4002C020))
23. #define rIOCON_P0_09 (*(volatile unsigned *)(0x4002C024))
24. #define rIOCON_P1_16 (*(volatile unsigned *)(0x4002C0C0))
26. #define UDA1380_ADDRESS 0x1A
28. void Uda1380_WriteData(unsigned char reg, unsigned shortint data)
29. {
30. unsigned char config[3];
32. config[0] = reg;
33. config[1] = (data >> 8) & 0xFF; //MS
34. config[2] = data&0xFF; //LS
37. I2C0_MasterTransfer(UDA1380_ADDRESS, config, sizeof(config), 0, 0);
39. I2C0_MasterTransfer(UDA1380_ADDRESS, config, 1, &config[1], 2); //校验写入的数据是否正确
40. if((config[1]<<8|config[2]) != data)
41. {
42. while(1); //写入和读出的数据不一致
43. }
44. }
46. void Uda1380_config()
47. {
48. I2C0_Init();
50. Uda1380_WriteData(0x7F, 0x0); //restore L3-default values
51. Uda1380_WriteData(0x01, 0x0); //数据格式为标准的I2S格式
53. Uda1380_WriteData(0x13, 0x0); //配置音频的输出
54. Uda1380_WriteData(0x14, 0x0);
56. Uda1380_WriteData(0x00, 0x2|0x1<<8|0x1<<9); //使能DAC的时钟，选择使用SYSCLK产生128fs的时钟
57. Uda1380_WriteData(0x02,0x1<<15|0x1<<13|0x1<<10|0x1<<8); //使能DAC 电源
59. }
61. int main(void)
62. {
63. unsigned int count=0, i;
64. unsigned char flag=1;
66. rIOCON_P0_07 = (rIOCON_P0_07&(~0x3))|0x1; //I2S_TX_SCK
67. rIOCON_P0_08 = (rIOCON_P0_08&(~0x3))|0x1; //I2S_TX_WS
68. rIOCON_P0_09 = (rIOCON_P0_09&(~0x3))|0x1; //I2S_TX_SDA
69. rIOCON_P1_16 = (rIOCON_P1_16&(~0x3))|0x2; //I2SMCLK
70. rPCONP |= 0x1<<27;
72. rI2SDAO = (16 - 1)<<6 | 0x1<<4 | 0x1<<3 |0x1; //16位, 立体音，禁止发送
74. rI2STXMODE |= 0x1<<3; //使能MCLK输出，使TX_REF输出到UDA1380的SYSCLK引脚
76. rI2STXRATE = 0x1<<8|0x1; //配置分数速率寄存器得到TX_REF=CCLK/(1/1)/2
77. rI2STXBITRATE = CCLK/2/(44100*2*16) - 1; //44.1KHZ采样16位
79. for(i = 0; i <0x1000000; i++); //延时等待UDA1380内部通过SYSCLK产生稳定的128fs提供插值滤波和抽取滤波使用
81. Uda1380_config();
83. rI2SDAO &= ~ (1<<4);
84. rI2SDAO &= ~ (1<<3);
85. rI2SDAO &= ~ (1<<15); //启动I2S数据传输
87. while(flag)
88. {
89. if(((rI2SSTATE>>16)&0xFF)<=4) //如果发送FIFO中的数据小于或等于4个字
90. {
91. for(i=0; i<8-(((rI2SSTATE>>16)&0xFF)); i++) //将FIFO填充到8个字
92. {
93. rI2STXFIFO = *(unsigned int *)(audio + count); //转换成int类型的指针，从指针指向的位置读取32位数据
95. count+=4; //读取一个字，相当于读取char类型数组中的4个元素
97. if(count>=sizeof(audio)) //数组中的数据发送完
98. {
99. flag = 0;
100. break;
101. }
102. }
103. }
104. }
106. rI2SDAO |= 0x1<<3|0x1<<4; //停止I2S传输
108. return 0;
109. }
```
#include "i2c.h"
#include "audio.h"

#define rI2SDAO         (*(volatile unsigned *)(0x400A8000))
#define rI2STXFIFO      (*(volatile unsigned *)(0x400A8008))
#define rI2STXRATE      (*(volatile unsigned *)(0x400A8020))
#define rI2STXBITRATE   (*(volatile unsigned *)(0x400A8028))
#define rI2STXMODE      (*(volatile unsigned *)(0x400A8030))

#define rI2SDMA1        (*(volatile unsigned *)(0x400A8014))
#define rI2SDMA2        (*(volatile unsigned *)(0x400A8018))
#define rI2SSTATE       (*(volatile unsigned *)(0x400A8010))
#define rI2SIRQ         (*(volatile unsigned *)(0x400A801C))

#define rI2SDAI         (*(volatile unsigned *)(0x400A8004))
#define rI2SRXFIFO      (*(volatile unsigned *)(0x400A800C))
#define rI2SRXRATE      (*(volatile unsigned *)(0x400A8024))
#define rI2SRXBITRATE   (*(volatile unsigned *)(0x400A802C))
#define rI2SRXMODE      (*(volatile unsigned *)(0x400A8034))

#define rIOCON_P0_07	(*(volatile unsigned *)(0x4002C01C))
#define rIOCON_P0_08	(*(volatile unsigned *)(0x4002C020))
#define rIOCON_P0_09	(*(volatile unsigned *)(0x4002C024))
#define rIOCON_P1_16	(*(volatile unsigned *)(0x4002C0C0))

#define UDA1380_ADDRESS 0x1A

void Uda1380_WriteData(unsigned char reg, unsigned short int data)
{
    unsigned char config[3];
    
    config[0] = reg;
    config[1] = (data >> 8) & 0xFF;    //MS
    config[2] = data&0xFF;             //LS
    
    
    I2C0_MasterTransfer(UDA1380_ADDRESS, config, sizeof(config), 0, 0);
    
    I2C0_MasterTransfer(UDA1380_ADDRESS, config, 1, &config[1], 2);     //校验写入的数据是否正确
    if((config[1]<<8|config[2]) != data)
    {
        while(1);   //写入和读出的数据不一致
    }
}

void Uda1380_config()
{
    I2C0_Init();
    
    Uda1380_WriteData(0x7F, 0x0);         //restore L3-default values
    Uda1380_WriteData(0x01, 0x0);         //数据格式为标准的I2S格式
    
    Uda1380_WriteData(0x13, 0x0);         //配置音频的输出
    Uda1380_WriteData(0x14, 0x0);           

    Uda1380_WriteData(0x00, 0x2|0x1<<8|0x1<<9);     //使能DAC的时钟，选择使用SYSCLK产生128fs的时钟
    Uda1380_WriteData(0x02,0x1<<15|0x1<<13|0x1<<10|0x1<<8); //使能DAC 电源
    
}

int main(void)
{   
    unsigned int count=0, i;
    unsigned char flag=1;
    
    rIOCON_P0_07 = (rIOCON_P0_07&(~0x3))|0x1;   //I2S_TX_SCK
    rIOCON_P0_08 = (rIOCON_P0_08&(~0x3))|0x1;   //I2S_TX_WS
    rIOCON_P0_09 = (rIOCON_P0_09&(~0x3))|0x1;   //I2S_TX_SDA
    rIOCON_P1_16 = (rIOCON_P1_16&(~0x3))|0x2;   //I2SMCLK
    rPCONP |= 0x1<<27;
    
    rI2SDAO = (16 - 1)<<6 | 0x1<<4 | 0x1<<3  |0x1;  //16位, 立体音， 禁止发送

    rI2STXMODE |= 0x1<<3;       //使能MCLK输出，使TX_REF输出到UDA1380的SYSCLK引脚
    
    rI2STXRATE = 0x1<<8|0x1;    //配置分数速率寄存器 得到TX_REF=CCLK/(1/1)/2
    rI2STXBITRATE = CCLK/2/(44100*2*16) - 1;  //44.1KHZ采样16位
    
    for(i = 0; i <0x1000000; i++);  //延时 等待UDA1380内部通过SYSCLK产生稳定的128fs提供插值滤波和抽取滤波使用
    
    Uda1380_config();
    
    rI2SDAO &= ~ (1<<4);
    rI2SDAO &= ~ (1<<3);
    rI2SDAO &= ~ (1<<15);   //启动I2S数据传输
    
    while(flag)
    {
        if(((rI2SSTATE>>16)&0xFF)<=4)       //如果发送FIFO中的数据小于或等于4个字
        {
            for(i=0; i<8-(((rI2SSTATE>>16)&0xFF)); i++)     //将FIFO填充到8个字
            {
                rI2STXFIFO = *(unsigned int *)(audio + count);  //转换成int类型的指针，从指针指向的位置读取32位数据
                
                count+=4;               //读取一个字，相当于读取char类型数组中的4个元素
               
                if(count>=sizeof(audio)) //数组中的数据发送完
                {
                    flag = 0;
                    break;
                }
            }
        }
    }
    
    rI2SDAO |= 0x1<<3|0x1<<4;   //停止I2S传输
    
    return 0;
}
```
下面对程序需要注意的做下说明：

1，i2c.h中是上一篇介绍I2C总线中所用的函数，aduio.h中存放的是音频数据的数组，const unsigned char audio[]={0,0,0,0,0,......................

2，I2C总线每次发送的数据为1个字节，而UDA1380的寄存器为16为，因此我们先发送高字节然后再发送低字节，具体的时序可以参考UDA1380的数据手册。

3，程序中配置发送控制寄存器I2STXMODE使能了MCLK输出TX_REF的时钟到UDA1380的SYSCLK引脚，而UDA1380中配置成使用该时钟产生内部滤波器需要的128fs的时钟。在图1中标志中说明run at ....因此在程序中配置UDA1380之前，使用了一个for延时，用于等待UDA1380内部产生稳定的128fs时钟。只有这样才能正确的配置0x10之后的滤波器相关寄存器。否则对0x10之后的滤波器相关寄存器操作会失败。这点没有验证，但是在debug调试的时候可以正常的有声音输出，但是下载到板子上运行，则没有效果。如果去掉for循环延时效果也不正常发音。如果不使能MCLK输出，则写0x13寄存器的值不会成功，读取该寄存器的值永远都是其默认值。因此推测和UDA1380的SYSCLK产生内部滤波器使用的128fs时钟有关。

参考了linux内核里面的uda1380的驱动，其中也提到了配置0x10以后的滤波器相关寄存器要满足条件
[plain] view plain copy print ?
1. 107 /* the interpolator & decimator regs must only be written when the
2. 108 * codec DAI is active.
3. 109 */
```
107         /* the interpolator & decimator regs must only be written when the
108          * codec DAI is active.
109          */
```
谁有这方面的经验，希望多指教！
作者：tdyizhen1314（一位从事软硬件开发十年以上的老兵的故事，希望与大家一起交流，共同进步）邮箱：495567686@qq.com
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原文地址：https://www.cnblogs.com/tdyizhen1314/p/2704610.html