/**********************按键实验*********************************/
// 公司名称 ：保定飞凌嵌入式技术有限公司
// 描 述 ：按键控制蜂鸣器
// 版 权 ：保定飞凌嵌入式技术有限公司
// 网 址 ：www.witech.com.cn
/***************************************************************/
/*
本实验接口说明
*/
#include "2440addr.h"
/*-----------------------函数声明----------------------------*/
extern void Uart_Printf(char *fmt,...);
void Wr24C02(U32 slvAddr,U32 addr,U8 data);
void Rd24C02(U32 slvAddr,U32 addr,U8 *data);
void Run_IicPoll(void);
void IicPoll(void) ;
void Delay(int x) ;
static U8 iicData[IICBUFSIZE];
static volatile int iicDataCount;
static volatile int iicStatus;
static volatile int iicMode;
static int iicPt;
/*------------------------------------------------------------/
函数名称： iicMain
功能描述： 入口函数
传 参： int count
返 回 值： 无
-------------------------------------------------------------*/
void iicMain(void)
{
unsigned int i,j;
static U8 data[256];
Uart_Printf("IIC Test(Polling) using AT24C02\n");
//设置GPE15->IICSDA 和 GPE14->IICSCL
rGPEUP |= 0xc000; //关断上拉
rGPECON &= ~0xf0000000;
rGPECON |= 0xa0000000; //GPE15:IICSDA , GPE14:IICSCL
//使能ACK, 预分频 IICCLK=PCLK/16, 使能中断, 发送时钟 Tx clock=IICCLK/16
rIICCON = (1<<7) | (0<<6) | (1<<5) | (0xf);
rIICADD = 0x10; //2440 从地址 = [7:1]
rIICSTAT = 0x10; //IIC总线数据输出使能(Rx/Tx)
Uart_Printf("Write test data into AT24C02\n");
//写入一个page的数据，page的大小是256byte，
//page 的起始地址是0xa0，写入的数据是：0、1、2、...255。0xa0是AT24C02的页地址。
//AT24C02的页地址是0x00/0x20/0x40/0x60/0x80/0xa0/0xc0/0xe0。
for(i=0;i<256;i++)
Wr24C02(0xa0,(U8)i,i); //U32 slvAddr,U32 addr,U8 data
for(i=0;i<256;i++) //初始化data数组的值为0。
data[i] = 0;
Uart_Printf("Read test data from AT24C02\n");
for(i=0;i<256;i++) //读24C02的0xa0地址中数据到data数组中。
Rd24C02(0xa1,(U8)i,&(data[i]));
for(i=0;i<16;i++) //输出data数组接收数据的值
{
for (j=0;j<16;j++)
Uart_Printf("%2x ",data[i*16+j]);
Uart_Printf("\n");
}
Uart_Printf("OK! Write data is same to Read data!\n");
while(1);
}
/*------------------------------------------------------------/
函数名称： Wr24C02
功能描述： 写24c02
传 参： U32 slvAddr,U32 addr,U8 data
返 回 值： 无
-------------------------------------------------------------*/
void Wr24C02(U32 slvAddr,U32 addr,U8 data)
{
iicMode = WRDATA;
iicPt = 0;
iicData[0] = (U8)addr;
iicData[1] = data;
iicDataCount = 2;
//8-bit data shift register for IIC-bus Tx/Rx operation.
rIICDS = slvAddr; //0xa0
//Master Tx mode, Start(Write), IIC-bus data output enable
//Bus arbitration sucessful, Address as slave status flag Cleared,
//Address zero status flag cleared, Last received bit is 0
rIICSTAT = 0xf0;
//Clearing the pending bit isn't needed because the pending bit has been cleared.
while(iicDataCount!=-1)
Run_IicPoll();
iicMode = POLLACK;
while(1)
{
rIICDS = slvAddr;
iicStatus = 0x100; //To check if _iicStatus is changed
rIICSTAT = 0xf0; //Master Tx, Start, Output Enable, Sucessful, Cleared, Cleared, 0
rIICCON = 0xe0;//0xaf; //Resumes IIC operation. //hzh
while(iicStatus==0x100)
Run_IicPoll();
if(!(iicStatus & 0x1))
break; //When ACK is received
}
rIICSTAT = 0xd0; //Master Tx condition, Stop(Write), Output Enable
rIICCON = 0xe0;//0xaf; //Resumes IIC operation. //hzh
Delay(1); //Wait until stop condtion is in effect.
}
/*------------------------------------------------------------/
函数名称： Rd24C02
功能描述： 读24c02
传 参： U32 slvAddr,U32 addr,U8 *data
返 回 值： 无
-------------------------------------------------------------*/
void Rd24C02(U32 slvAddr,U32 addr,U8 *data)
{
iicMode = SETRDADDR;
iicPt = 0;
iicData[0] = (U8)addr;
iicDataCount = 1;
rIICDS = slvAddr;
rIICSTAT = 0xf0; //MasTx,Start
//Clearing the pending bit isn't needed because the pending bit has been cleared.
while(iicDataCount!=-1)
Run_IicPoll();
iicMode = RDDATA;
iicPt = 0;
iicDataCount = 1;
rIICDS = slvAddr;
rIICSTAT = 0xb0; //主接收开始
rIICCON = 0xe0; //Resumes IIC operation.
while(iicDataCount!=-1)
Run_IicPoll();
*data = iicData[1];
}
/*------------------------------------------------------------/
函数名称： Run_IicPoll
功能描述：
传 参： 无
返 回 值： 无
-------------------------------------------------------------*/
void Run_IicPoll(void)
{
if(rIICCON & 0x10) //Tx/Rx Interrupt Enable
IicPoll();
}
/*------------------------------------------------------------/
函数名称： IicPoll
功能描述：
传 参： 无
返 回 值： 无
-------------------------------------------------------------*/
void IicPoll(void)
{
U32 iicSt,i;
iicSt = rIICSTAT;
if(iicSt & 0x8){}; //When bus arbitration is failed. 总线仲裁失败
if(iicSt & 0x4){}; //When a slave address is matched with IICADD
if(iicSt & 0x2){}; //When a slave address is 0000000b
if(iicSt & 0x1){}; //When ACK isn't received
switch(iicMode)
{
case POLLACK:
iicStatus = iicSt;
break;
case RDDATA:
if((iicDataCount--)==0)
{
iicData[iicPt++] = rIICDS;
rIICSTAT = 0x90; //Stop MasRx condition
rIICCON = 0xe0; //Resumes IIC operation.
Delay(1); //Wait until stop condtion is in effect.
//Too long time...
//The pending bit will not be set after issuing stop condition.
break;
}
iicData[iicPt++] = rIICDS;
//The last data has to be read with no ack.
if((iicDataCount)==0)
rIICCON = 0x60;//0x2f; //Resumes IIC operation with NOACK.
else
rIICCON = 0xe0;//0xaf; //Resumes IIC operation with ACK
break;
case WRDATA:
if((iicDataCount--)==0)
{
rIICSTAT = 0xd0; //stop MasTx condition
rIICCON = 0xe0;//0xaf; //resumes IIC operation.
Delay(1); //wait until stop condtion is in effect.
//The pending bit will not be set after issuing stop condition.
break;
}
rIICDS = iicData[iicPt++]; //_iicData[0] has dummy.
for(i=0;i<10;i++); //for setup time until rising edge of IICSCL
rIICCON = 0xe0;//0xaf; //resumes IIC operation.
break;
case SETRDADDR:
if((iicDataCount--)==0)
break; //IIC operation is stopped because of IICCON[4]
rIICDS = iicData[iicPt++];
for(i=0;i<10;i++); //for setup time until rising edge of IICSCL
rIICCON = 0xe0;//0xaf; //resumes IIC operation.
break;
default:
break;
}
}
/*------------------------------------------------------------/
函数名称： Delay
功能描述： 延时函数
传 参： int x
返 回 值： 无
-------------------------------------------------------------*/
void Delay(int x)
{
int k, j;
while(x)
{
for (k=0;k<=0xff;k++)
for(j=0;j<=0xff;j++);
x--;
}
} #include <stdarg.h>
#include "2440addr.h"
void Uart_Init(int baud)
{
int i;
rUFCON0 = 0x0; //UART channel 0 FIFO control register, FIFO disable
//UART0
rULCON0 = 0x3; //Line control register : Normal,No parity,1 stop,8 bits
// [10] [9] [8] [7] [6] [5] [4] [3:2] [1:0]
// Clock Sel, Tx Int, Rx Int, Rx Time Out, Rx err, Loop-back, Send break, Transmit Mode, Receive Mode
// 0 1 0 , 0 1 0 0 , 01 01
// PCLK Level Pulse Disable Generate Normal Normal Interrupt or Polling
rUCON0 = 0x805; // Control register
rUBRDIV0=( (int)(50000000/16./baud+0.5) -1 ); //Baud rate divisior register 0
//UART1
for(i=0;i<100;i++);
}
//=====================================================================
void Uart_SendByte(int data)
{
if(data=='\n')
{
while(!(rUTRSTAT0 & 0x2));
// Delay(1); //because the slow response of hyper_terminal
WrUTXH0('\r');
}
while(!(rUTRSTAT0 & 0x2)); //Wait until THR is empty.
// Delay(1);
WrUTXH0(data);
}
//====================================================================
void Uart_SendString(char *pt)
{
while(*pt)
Uart_SendByte(*pt++);
}
//=====================================================================
//If you don't use vsprintf(), the code size is reduced very much.
void Uart_Printf(char *fmt,...)
{
va_list ap;
char str[255];
va_start(ap,fmt);
vsprintf(str,fmt,ap);
Uart_SendString(str);
va_end(ap);
} AREA |DATA|,CODE,READONLY
ENTRY
ldr r13,=0x1000
IMPORT iicMain
b iicMain
END 1. 通过UART0发送一个字符的数据（INT8U data）的发送语句是什么？该语句能得到执行的条件是什么？把该条件写成C语言语句。
2. 准备把要接收的字符放在INT8U类型的变量reData中，则接收一个字符的语句是什么？接收到字符的条件是什么？把该条件写成C语言语句。
3. 预定义语句 #define rUTXH0 (*(volatile unsigned *) 0x50000020)中，关键字volatile的作用是什么？unsigned * 的作用的是什么？第一个*的作用是什么？ rUTXH0代表的是什么特殊功能寄存器？其功能是什么？
4. 以下两条语句的具体作用是什么？
ULCON0 &=0xFFFFFF00;
ULCON0 |=0x03;
5. 若PCLK为50MHz，UART0使用的波特率是115200pbs，则给rUBRDIV0 赋的值是多少？
6. S3C2410A的IIC总线有哪两条信号线？这两条信号线的作用分别是什么？为使用这两条信号线，对IIC接口的管脚该做如何设置？IIC是如何发出开始信号和停止信号的？
本文介绍了如何使用C语言通过内存映射的方式访问特定的内存地址，特别关注于嵌入式系统中的寄存器和I/O端口。通过具体实例展示了如何定义内存映射的宏，并解释了使用volatile关键字的原因及其重要性。
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