/* ***************************
 Website:  http://wch.cn
 Email:    tech@wch.cn
 Author:   W.ch 2005.4
 CH452 的2線接口子程序
****************************
 CH452的2線接口，不含按鍵中斷為2個I/O引腳，含按鍵中斷為3個I/O，兼容I2C/IIC時序
 對于頻率低于24MHz的MCS51，為了節約傳輸時間，可以適當減少SCL/SDA之間的延時
*************************************************************************** */
#include	"PIN.H"			// 修改該文件以適應硬件環境/單片機型號等
#include	"CH452CMD.H"	// CH452常量定義

void CH452_I2c_Start(void)  // 操作起始
{
	DISABLE_KEY_INTERRUPT;  //禁止鍵盤中斷,防止開始時被CH452中斷而進入中斷服務程序中的START
	CH452_SDA_SET;   /*發送起始條件的數據信號*/
	CH452_SDA_D_OUT;   /* 設置SDA為輸出方向 */
	CH452_SCL_SET;
	CH452_SCL_D_OUT;   /* 設置SCL為輸出方向 */
	DELAY_1US;
	CH452_SDA_CLR;   /*發送起始信號*/
	DELAY_1US;      
	CH452_SCL_CLR;   /*鉗住I2C總線，準備發送或接收數據 */
	DELAY_1US;
}

void CH452_I2c_Stop(void)  // 操作結束
{
	CH452_SDA_CLR;
	CH452_SDA_D_OUT;   /* 設置SDA為輸出方向 */
	DELAY_1US;
	CH452_SCL_SET;
	DELAY_1US;
	CH452_SDA_SET;  /*發送I2C總線結束信號*/
	DELAY_1US;
	CH452_SDA_D_IN;   /* 設置SDA為輸入方向 */
	DELAY_1US;
  	ENABLE_KEY_INTERRUPT;
}

void CH452_I2c_WrByte(unsigned char dat)	//寫一個字節數據
{
	unsigned char i;
	CH452_SDA_D_OUT;   /* 設置SDA為輸出方向 */
	for(i=0;i!=8;i++)  // 輸出8位數據
	{
		if(dat&0x80) {CH452_SDA_SET;}
		else {CH452_SDA_CLR;}
		DELAY_1US;
		CH452_SCL_SET;
		dat<<=1;
		DELAY_1US;
		DELAY_1US;
		CH452_SCL_CLR;
		DELAY_1US;
	}
	CH452_SDA_D_IN;   /* 設置SDA為輸入方向 */
	CH452_SDA_SET;
	DELAY_1US;
	CH452_SCL_SET;  // 接收應答
	DELAY_1US;
	DELAY_1US;
	CH452_SCL_CLR;
	DELAY_1US;
}

unsigned char  CH452_I2c_RdByte(void)		//讀一個字節數據
{
	unsigned char dat,i;
	CH452_SDA_SET;
	CH452_SDA_D_IN;   /* 設置SDA為輸入方向 */
	dat=0;
	for(i=0;i!=8;i++)  // 輸入8位數據
	{
		CH452_SCL_SET;
		DELAY_1US;
		DELAY_1US;
		dat<<=1;
		if(CH452_SDA_IN) dat++;  // 輸入1位
		CH452_SCL_CLR;
		DELAY_1US;
//		DELAY_1US;
	}
	CH452_SDA_SET;
	DELAY_1US;
	CH452_SCL_SET;  // 發出無效應答
	DELAY_1US;
	DELAY_1US;
	CH452_SCL_CLR;
	DELAY_1US;
	return(dat);
}

void CH452_Write(unsigned short cmd)	//寫命令
{
	CH452_I2c_Start();               /*啟動總線*/
#ifdef	ENABLE_2_CH452				// 若有兩個CH452并連
   	CH452_I2c_WrByte((unsigned char)(cmd>>7)&CH452_I2C_MASK|CH452_I2C_ADDR0);  // CH452的ADDR=0時
#else 
   	CH452_I2c_WrByte((unsigned char)(cmd>>7)&CH452_I2C_MASK|CH452_I2C_ADDR1);  // CH452的ADDR=1時(默認)
#endif
   	CH452_I2c_WrByte((unsigned char)cmd);     /*發送數據*/
  	CH452_I2c_Stop();                 /*結束總線*/ 
}

unsigned char CH452_Read(void)		//讀取按鍵
{
	unsigned char keycode;
   	CH452_I2c_Start();                /*啟動總線*/
   	CH452_I2c_WrByte((unsigned char)(CH452_GET_KEY>>7)&CH452_I2C_MASK|0x01|CH452_I2C_ADDR1);    // 若有兩個CH452并連,當ADDR=0時,需修改為CH452_I2C_ADDR0
   	keycode=CH452_I2c_RdByte();      /*讀取數據*/
	CH452_I2c_Stop();                /*結束總線*/ 
	return(keycode);
}