單片機(jī)模擬I2C總線及AT24C01應(yīng)用實(shí)例

1、 SETBSCLNOPNOPSETBSDARET;發(fā)送接收確認(rèn)信號(hào)I2C_ACk:應(yīng)答信號(hào)SETBSDASETBSCLNOPNOPJBSDA,I2C_ACK0CLRCSJMPI2C_ACK_ENDI2C_ACK0:SETBCI2C_ACK_END:CLRSCLRET;送八位數(shù)據(jù)I2C_SEND8BIT:MOVB,#08HI2C_SEND8BIT_A:RLCAMOVSDA,CSETBSCLNOPNOPCLRSCLDJNZB,I2C_SEND8BIT_ARET;接收八位數(shù)據(jù)I2C_RECEIVE8BIT:MOVB,#08HCLRA；SETBSDAI2C_RECEIVE8IT_A:SETBSCLNO

2、PNOPMOVC,SDARLCA;將讀取數(shù)據(jù)通過(guò)C逐為移入累加器A中8次移動(dòng)后就完成一個(gè)字節(jié)的接收。CLRSCLCLRSCL;SCL為低電平時(shí)才允許SDA數(shù)據(jù)改變數(shù)據(jù)指針自動(dòng)加1指向下一位數(shù)據(jù)。DJNZB,I2C_RECEIVE8IT_ARET5.C語(yǔ)言寫(xiě)的24C01單字節(jié)讀寫(xiě)程序/*=24C01存儲(chǔ)器I2C總線實(shí)驗(yàn)C語(yǔ)言例子ew51仿真編程器配套實(shí)驗(yàn)板學(xué)習(xí)例程中山單片機(jī)學(xué)習(xí)網(wǎng)智佳科技站長(zhǎng)：逸風(fēng)E-mail:=*/#include#includesbitSDA=0 x90;sbitSCL=0 x91;/函數(shù)聲明unsignedchari2c_read(unsignedchar);voidi2c

3、_write(unsignedchar,unsignedchar);voidi2c_send8bit(unsignedchar);unsignedchari2c_receive8bit(void);voidi2c_start(void);voidi2c_stop(void);biti2c_ack(void);/=voidmain(void)unsignedchardd;i2c_write(0 x00,0 x55);_nop_();dd=i2c_read(0 x00);for(;)/*=i2c_write(地址，數(shù)據(jù)),寫(xiě)一個(gè)字節(jié)=*/voidi2c_write(unsignedcharAddr

4、ess,unsignedcharData)doi2c_start();i2c_send8bit(0 xA0);while(i2c_ack();i2c_send8bit(Address);i2c_ack();i2c_send8bit(Data);i2c_ack();i2c_stop();return;/*=i2c_read(地址，數(shù)據(jù)),寫(xiě)一個(gè)字節(jié)=*/unsignedchari2c_read(unsignedcharAddress)unsignedcharc;doi2c_start();i2c_send8bit(0 xA0);while(i2c_ack();/=1，表示無(wú)確認(rèn)，再次發(fā)送i2c_

5、send8bit(Address);i2c_ack();doi2c_start();i2c_send8bit(0 xA1);while(i2c_ack();c=i2c_receive8bit();i2c_ack();i2c_stop();return(c);/=/發(fā)送開(kāi)始信號(hào)voidi2c_start(void)SDA=1;SCL=1;SDA=0;SCL=0;return;/發(fā)送結(jié)束信號(hào)voidi2c_stop(void)SDA=0;SCL=1;SDA=1;return;/發(fā)送接收確認(rèn)信號(hào)biti2c_ack(void)bitack;SDA=1;SCL=1;if(SDA=1)ack=1;els

6、eack=0;SCL=0;returnack);/送八位數(shù)據(jù)voidi2c_send8bit(unsignedcharb)unsignedchara;for(a=0;a8;a+)if(bA)&0X80)FONTSDA=1;elseSDA=0;SCL=1;SCL=0;return;/接收八位數(shù)據(jù)unsignedchari2c_receive8bit(void)unsignedchara;unsignedcharb=0;for(a=0;a8;a+)SCL=1;b=b1;if(SDA=1)b=b|0 x01;/按位或SCL=0;return(b);6在I2C總線的應(yīng)用中應(yīng)注意的事項(xiàng)總結(jié)為以下幾點(diǎn)：嚴(yán)格按照時(shí)序圖的要求進(jìn)行操作若與口線上帶內(nèi)部上拉電阻的單片機(jī)接口連接，可以不外加上拉電阻。程序中為配合相應(yīng)的傳輸速率，在對(duì)口線操作的指令后可用NOP指令加一定的延時(shí)。4)為了減少意外的干擾信號(hào)將EEPROM內(nèi)的數(shù)據(jù)改寫(xiě)可在EEPROM內(nèi)部沒(méi)有用的空間寫(xiě)入標(biāo)志字