/*****************************************************
*說 明：S3C2440 I2C實現(xiàn)
*****************************************************/
1:I2C原理
總線的構成及信號類型 I2C總線是由數(shù)據(jù)線SDA和時鐘SCL構成的串行總線，可發(fā)送和接收數(shù)據(jù)。在CPU與被控IC之間、IC與IC之間進行雙向傳送，最高傳送速率100kbps。各種被控制電路均并聯(lián)在這條總線上，但就像電話機一樣只有撥通各自的號碼才能工作，所以每個電路和模塊都有唯一的地址，在信息的傳輸過程中，I2C總線上并接的每一模塊電路既是主控器（或被控器），又是發(fā)送器（或接收器），這取決于它所要完成的功能。CPU發(fā)出的控制信號分為地址碼和控制量兩部分，地址碼用來選址，即接通需要控制的電路，確定控制的種類；控制量決定該調整的類別（如對比度、亮度等）及需要調整的量。這樣，各控制電路雖然掛在同一條總線上，卻彼此獨立，互不相關。 I2C總線在傳送數(shù)據(jù)過程中共有三種類型信號， 它們分別是：開始信號、結束信號和應答信號。 開始信號：SCL為高電平時，SDA由高電平向低電平跳變，開始傳送數(shù)據(jù)。 結束信號：SCL為高電平時，SDA由低電平向高電平跳變，結束傳送數(shù)據(jù)。 應答信號：接收數(shù)據(jù)的從控器在接收到8bit數(shù)據(jù)后，向發(fā)送數(shù)據(jù)的主控器發(fā)出特定的低電平脈沖，表示已收到數(shù)據(jù)。CPU向從控器發(fā)出一個信號后，等待從控器發(fā)出一個應答信號，CPU接收到應答信號后，根據(jù)實際情況作出是否繼續(xù)傳遞信號的判斷。若未收到應答信號，判斷為受控單元出現(xiàn)故障。 這些信號中，起始信號是必需的，結束信號和應答信號，都可以不要。
2：I2C實驗代碼
/*
---------------------------------------------------------------
文件名稱:I2C.c
說 明:I2C協(xié)議 讀寫AT24C08
作 者:溫子祺
創(chuàng)建時間:2010-08-17
測試結果:[OK]
注意事項:
(1)24C02數(shù)據(jù)速率I2C總線的數(shù)據(jù)傳送速率在標準工作方式下為100kbit/s，
在快速方式下，最高傳送速率可達400kbit/s。
(2)當前S3C2440各頻率如下:FCLK 405MHz
HCLK 135MHz
PCLK 67.5MHz
(3)當前I2C協(xié)議在三星提供的源代碼進行修改，并提升代碼的容錯能力
如I2C進行讀寫時,都有進行超時處理。
---------------------------------------------------------------
*/
#include "S3C244x.h"
#include "Global.h"
#include "IIC.h"
/*
1:rIICON IIC總線控制寄存器
2:rIICSTAT IIC總線控制狀態(tài)寄存器
3:rIICADD IIC總線地址寄存器
4:rIICDS IIC總線發(fā)送接收數(shù)據(jù)移位寄存器
5:rIICLC IIC總線多主設備線路控制寄存器
*/
/*
====================================================
I2C基本函數(shù)接口
====================================================
*/
static volatile UINT8 g_ucI2CDataBuf[256]; //I2C發(fā)送數(shù)據(jù)緩沖區(qū)
static volatile UINT32 g_unI2CCurDataCount; //I2C當前數(shù)據(jù)計數(shù)
static volatile UINT32 g_unI2CCurStatus; //I2C當前狀態(tài)
static volatile UINT32 g_unI2CCurDataOffset; //I2C當前發(fā)送數(shù)據(jù)偏移量
static UINT32 g_unI2CCurMode; //I2C當前模式
static UINT32 g_unIICCONSave; //臨時保存rIICCON寄存器值
static void __irq I2CISR(void) ; //I2C中斷服務函數(shù)
static BOOL I2CWriteByte(UINT32 unSlaveAddress,UINT32 ucWriteAddress,UINT8 *pucWriteByte);
static BOOL I2CReadByte (UINT32 unSlaveAddress,UINT32 ucReadAddress ,UINT8 *pucReadByte);
/******************************************************
*文件名稱:I2CWriteByte
*輸 入:unSlaveAddress 從機地址
unWriteAddress 寫地址
pucWriteByte 寫字節(jié)
*輸 出:TRUE/FALSE
*功能說明:I2C 寫單個字節(jié)
*注意事項:
主機發(fā)送起始信號后，發(fā)送一個尋址字節(jié)，收到應答后緊跟著的就是數(shù)據(jù)傳輸，
數(shù)據(jù)傳輸一般由主機產(chǎn)生的停止位終止。但是，如果主機仍希望在總線上通訊，
它可以產(chǎn)生重復起始信號和尋址另一個從機，而不是首先產(chǎn)生一個停止信號。
在這種傳輸中，可能有不同的讀/寫格式。
*******************************************************/
static BOOL I2CWriteByte(UINT32 unSlaveAddress,
UINT32 unWriteAddress,
UINT8 *pucWriteByte)
{
BOOL bRt=TRUE;
UINT32 unTimeouts;
g_unI2CCurMode = WRDATA; //當前I2C模式:寫
g_unI2CCurDataOffset= 0; //I2C數(shù)據(jù)緩沖區(qū)偏移量為0
g_ucI2CDataBuf[0] = (UINT8)unWriteAddress; //寫地址
g_ucI2CDataBuf[1] = *pucWriteByte; //寫數(shù)據(jù)
g_unI2CCurDataCount = 2; //當前數(shù)據(jù)計數(shù)值(即地址+數(shù)據(jù)=2字節(jié))
rIICDS = unSlaveAddress; //0xa0(高四位默認是1010,低四位為xxxx)
rIICSTAT = 0xf0; //主機發(fā)送啟動
unTimeouts=1000;
while(g_unI2CCurDataCount!=-1 && unTimeouts--)
{
DelayNus(1);
}
if(!unTimeouts)
{
bRt=FALSE;
goto end;
}
g_unI2CCurMode = POLLACK;
while(1)
{
rIICDS = unSlaveAddress;
g_unI2CCurStatus = 0x100;
rIICSTAT = 0xf0; //主機發(fā)送啟動
rIICCON=g_unIICCONSave; //恢復I2C運行
unTimeouts=1000;
while(g_unI2CCurStatus==0x100 && unTimeouts--)
{
DelayNus(1);
}
if(!unTimeouts)
{
bRt=FALSE;
goto end;
}
if(!(g_unI2CCurStatus&0x1))
{
break; //接收到應答(ACK)信號
}
}
end:
rIICSTAT = 0xd0; //停止主機發(fā)送狀態(tài)Stop MasTx condition
rIICCON = g_unIICCONSave; //恢復I2C運行
DelayNus(10); //等待直到停止條件是有效的
return bRt;
}
/******************************************************
*文件名稱:I2CReadByte
*輸 入:unSlaveAddress 從機地址
unReadAddress 讀地址
pucReadByte 讀字節(jié)
*輸 出:TRUE/FALSE
*功能說明:I2C 讀單個字節(jié)
*注意事項:
主機發(fā)送完尋址字節(jié)后，主機立即讀取從機中的數(shù)據(jù)。
當尋址字節(jié)的"R/W"位為1時，在從機產(chǎn)生應答信號后，
主機發(fā)送器變成主機接收器，從機接收器變成從機發(fā)送器。
之后，數(shù)據(jù)由從機發(fā)送，主機接收，每個應答由主機產(chǎn)生，
時鐘信號CLK仍由主機產(chǎn)生。若主機要終止本次傳輸，則發(fā)送
一個非應答信號，接著主機產(chǎn)生停止信號
*******************************************************/
static BOOL I2CReadByte(UINT32 unSlaveAddress,
UINT32 unReadAddress,
UINT8 *pucReadByte)
{
BOOL bRt=TRUE;
UINT32 unTimeouts;
g_unI2CCurMode = SETRDADDR;
g_unI2CCurDataOffset= 0;
g_ucI2CDataBuf[0] = (UINT8)unReadAddress;
g_unI2CCurDataCount = 1;
rIICDS = unSlaveAddress;
rIICSTAT = 0xf0; //主機發(fā)送啟動
unTimeouts=1000;
while(g_unI2CCurDataCount!=-1 && unTimeouts--)
{
DelayNus(1);
}
if(!unTimeouts)
{
bRt=FALSE;
goto end;
}
g_unI2CCurMode = RDDATA;
g_unI2CCurDataOffset = 0;
g_unI2CCurDataCount = 1;
rIICDS = unSlaveAddress;
rIICSTAT = 0xb0; //主機接收啟動
rIICCON = g_unIICCONSave; //恢復I2C運行
unTimeouts=1000;
while(g_unI2CCurDataCount!=-1 && unTimeouts--)
{
DelayNus(1);
}
if(!unTimeouts)
{
bRt=FALSE;
goto end;
}
*pucReadByte= g_ucI2CDataBuf[1];
end:
return bRt;
}
/******************************************************
*文件名稱:I2CWriteNBytes
*輸 入:unSlaveAddress 從機地址
unWriteAddress 寫地址
pucWriteByte 寫字節(jié)
unNumOfBytes 寫字節(jié)數(shù)
*輸 出:TRUE/FALSE
*功能說明:I2C 寫多個字節(jié)
*******************************************************/
BOOL I2CWriteNBytes(UINT32 unSlaveAddress,
UINT32 unWriteAddress,
UINT8 *pucWriteBytes,
UINT32 unNumOfBytes)
{
UINT32 unSpareOfBytes=unNumOfBytes;
while(unSpareOfBytes--)
{
if(!I2CWriteByte( unSlaveAddress,
unWriteAddress,
pucWriteBytes))
{
I2CMSG("I2C[ERROR]:fail to write data fail at address %d
success to write %d bytes rn",
unWriteAddress,(unNumOfBytes-unSpareOfBytes));
return FALSE;
}
unWriteAddress++;
pucWriteBytes++;
}
return TRUE;
}
/******************************************************
*文件名稱:I2CReadNBytes
*輸 入:unSlaveAddress 從機地址
unReadAddress 讀地址
unNumOfBytes
*輸 出:TRUE/FALSE
*功能說明:I2C 讀多個字節(jié)
*******************************************************/
BOOL I2CReadNBytes(UINT32 unSlaveAddress,
UINT32 unReadAddress,
UINT8 *pucReadByte,
UINT32 unNumOfBytes)
{
UINT32 unSpareOfBytes=unNumOfBytes;
while(unSpareOfBytes--)
{
if(!I2CReadByte( unSlaveAddress,
unReadAddress,
pucReadByte))
{
I2CMSG("I2C[ERROR]:fail to read data fail at address %d
success to read %d bytes rn",
unReadAddress,(unNumOfBytes-unSpareOfBytes));
return FALSE;
}
unReadAddress++;
pucReadByte++;
}
return TRUE;
}
/*
====================================================
中斷服務函數(shù)
====================================================
*/
/******************************************************
*文件名稱:I2CISR
*輸 入:無
*輸 出:無
*功能說明:I2C 中斷服務函數(shù)
*******************************************************/
void __irq I2CISR(void)
{
UINT32 unI2CStatus;
unI2CStatus = rIICSTAT;
if(unI2CStatus & 0x8){} //When bus arbitration is failed.
if(unI2CStatus & 0x4){} //When a slave address is matched with IICADD
if(unI2CStatus & 0x2){} //When a slave address is 0000000b
if(unI2CStatus & 0x1){} //When ACK isn't received
switch(g_unI2CCurMode)
{
case POLLACK:
g_unI2CCurStatus = unI2CStatus;
break;
case RDDATA:
if((g_unI2CCurDataCount--)==0)
{
g_ucI2CDataBuf[g_unI2CCurDataOffset++] = rIICDS;
rIICSTAT = 0x90; //停止I2C接收狀態(tài)
rIICCON = g_unIICCONSave; //恢復I2C運行
DelayNus(1); //等待直到停止條件是有效的
//The pending bit will not be set after issuing stop condition.
break;
}
g_ucI2CDataBuf[g_unI2CCurDataOffset++] = rIICDS; //The last data has to be read with no ack.
if((g_unI2CCurDataCount)==0)
rIICCON = 0x2f; //Resumes IIC operation with NOACK.
else
rIICCON = g_unIICCONSave; //Resumes IIC operation with ACK
break;
case WRDATA:
rIICDS = g_ucI2CDataBuf[g_unI2CCurDataOffset++]; //g_ucI2CDataBuf[0] has dummy.
DelayNus(10); //for setup time until rising edge of IICSCL
rIICCON = g_unIICCONSave; //恢復I2C運行
if((g_unI2CCurDataCount--)==0)
{
rIICSTAT = 0xd0; //Stop MasTx condition
rIICCON = g_unIICCONSave; //恢復I2C運行
DelayNus(10); //Wait until stop condtion is in effect.
//The pending bit will not be set after issuing stop condition.
}
break;
case SETRDADDR:
if((g_unI2CCurDataCount--)==0)
{
break;
}
//IIC operation is stopped because of IICCON[4]
rIICDS = g_ucI2CDataBuf[g_unI2CCurDataOffset++];
DelayNus(10); //For setup time until rising edge of IICSCL
rIICCON = g_unIICCONSave; //恢復I2C運行
break;
default:
break;
}
rSRCPND = BIT_IIC; //Clear pending bit
rINTPND = BIT_IIC;
}
/*
====================================================
測試代碼
====================================================
*/
/******************************************************
*文件名稱:I2CTest
*輸 入:無
*輸 出:無
*功能說明:I2C 測試代碼
*******************************************************/
void I2CTest(void)
{
UINT32 i;
UINT8 buf[256];
I2CMSG("nIIC Test(Interrupt) using AT24C02n");
rGPEUP |= 0xc000; //Pull-up disable
rGPECON |= 0xa00000; //GPE15:IICSDA , GPE14:IICSCL
rCLKCON |= 1<<16;
pISR_IIC = (UINT32)I2CISR;
rINTMSK &= ~(BIT_IIC);
/*
IIC時序太重要了，要認真設置好發(fā)送時鐘和接收數(shù)據(jù)時鐘
當前PCLK = 405/6 = 67.5MHz
IICCLK=67.5/16= 4.22MHz
Tx Clock = 4.22/11=0.384MHz
*/
g_unIICCONSave=rIICCON = (1<<7) | (0<<6) | (1<<5) | (0xa);
rIICADD = 0x10; //S3C2440 從機地址設置
rIICSTAT = 0x10; //I2C總線數(shù)據(jù)輸出使能(Rx/Tx)
rIICLC =(1<<2)|(1); //濾波器使能,SDA數(shù)據(jù)延時輸出
I2CMSG("Write test data into AT24C02n");
for(i=0;i<256;i++)
{
buf[i]=i;
}
I2CWriteNBytes(0xA0,0,buf,256);
for(i=0;i<256;i++)
buf[i] = 0;
I2CMSG("Read test data from AT24C02n");
I2CReadNBytes(0xA0,0,buf,256);
I2CMSG("Read Data Finishrn");
for(i=0;i<256;i++)
{
I2CMSG("%d ",buf[i]);
}
rINTMSK |= BIT_IIC;
}
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