(转)Cortex-M3 (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
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[*]#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 shortint data)
[*]{
[*] unsigned char config;
[*]
[*] config = reg;
[*] config = (data >> 8) & 0xFF; //MS
[*] config = data&0xFF; //LS
[*]
[*]
[*] I2C0_MasterTransfer(UDA1380_ADDRESS, config, sizeof(config), 0, 0);
[*]
[*] I2C0_MasterTransfer(UDA1380_ADDRESS, config, 1, &config, 2); //校验写入的数据是否正确
[*] if((config<<8|config) != 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;
[*]}
#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;
config = reg;
config = (data >> 8) & 0xFF; //MS
config = data&0xFF; //LS
I2C0_MasterTransfer(UDA1380_ADDRESS, config, sizeof(config), 0, 0);
I2C0_MasterTransfer(UDA1380_ADDRESS, config, 1, &config, 2); //校验写入的数据是否正确
if((config<<8|config) != 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
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[*]107 /* the interpolator & decimator regs must only be written when the
[*]108 * codec DAI is active.
[*]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！
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