MSP430I2C通信演示幻灯片

I2C通信,内容提要,I2C协议I2C通信I2C应用数码管和矩阵键盘,MSP430G2553引脚图,I2C线与,两条总线：串行时钟线SCL和串行数据线SDA,两条总线都被上拉电阻拉到VCC，线与输出。,I2C协议的基本规范,完整帧包括起始位、地址位、读写位、应答位、数据位、数据位、应答位.数据位、应答位、停止位。从起始位开始每帧数据都是9位，其中第一帧是7位从机地址+1位读写标识+1位数据接收应答位；后续的每帧都是8位数据+1位数据接收方应答。R/W=0，主机发数据，ACK由从机负责拉低；反之如此。,I2C协议的起止位,8,1.在时钟线高电平时，数据线下降沿代表了起始位START2.在时钟线高电平时，数据线上升沿代表了停止位STOP3.在时钟线高电平期间，数据线上的数据保持稳定4.数据线上的数据只有当时钟线低电平期间才能转换。,I2C的地址规范,7位地址模式,10位地址模式,I2C的多主机仲裁,小地址通信优先,仲裁过程中，多主机时钟实现“线与”功能。,/|/|MSP430F6638100k100kMSP430F6638slave|master-|-|XINP8.5/UCB0SDA|P8.5/UCB0SDAXIN|-|XOUT|XOUT|-|P8.6/UCB0SCL|P8.6/UCB0SCL|,主机在不停地发数据给从机，时钟为1MHz,例1：,#includeunsignedcharTXData;unsignedcharTXByteCtr;voidmain(void)WDTCTL=WDTPW+WDTHOLD;/StopWDTP8SEL|=BIT5+BIT6;/AssignP8.5toUCB0SDAandUCB0SCLP8DIR|=BIT6;/P8.6toUCB0SCLUCB0CTL1=UCSSEL_2+UCSWRST;/UseSMCLK,keepSWresetUCB0CTL0=UCMST+UCMODE_3+UCSYNC;/I2CMaster,synchronousmodeUCB0BR0=10;UCB0BR1=0;UCB0I2CSA=0 x48;/SlaveAddressis048hUCB0CTL1/Incrementdatabyte,主机,#pragmavector=USCI_B0_VECTOR_interruptvoidUSCI_B0_ISR(void)switch(_even_in_range(UCB0IV,12)case0:break;/Vector0:Nointerruptscase2:break;/Vector2:ALIFGcase4:break;/Vector4:NACKIFGcase6:break;/Vector6:STTIFGcase8:break;/Vector8:STPIFGcase10:break;/Vector10:RXIFGcase12:/Vector12:TXIFGif(TXByteCtr)/CheckTXbytecounterUCB0TXBUF=TXData;/LoadTXbufferTXByteCtr-;/DecrementTXbytecounterelseUCB0CTL1|=UCTXSTP;/I2CstopconditionUCB0IFG,#includevolatileunsignedcharRXData;voidmain(void)WDTCTL=WDTPW+WDTHOLD;/StopWDTP8SEL|=BIT5+BIT6;/AssignP8.5/6toUCB0SDAandUCB0SCLUCB0CTL1|=UCSWRST;/EnableSWresetUCB0CTL0=UCMODE_3+UCSYNC;/I2CSlave,synchronousmodeUCB0I2COA=0 x32;/OwnAddressis032hUCB0CTL1/EnterLPM0,enableinterrupts,从机,#pragmavector=USCI_B0_VECTOR_interruptvoidUSCI_B0_ISR(void)switch(_even_in_range(UCB0IV,12)case0:break;/Vector0:Nointerruptscase2:break;/Vector2:ALIFGcase4:break;/Vector4:NACKIFGcase6:break;/Vector6:STTIFGcase8:break;/Vector8:STPIFGcase10:/Vector10:RXIFGRXData=UCB0RXBUF;/GetRXdata_bic_SR_register_on_exit(LPM0_bits);/ExitLPM0break;case12:break;/Vector12:TXIFGdefault:break;,/|/|MSP430G2xx3100k100kMSP430G2xx3slave|master-|-|XINP1.7/UCB0SDA|P1.7/UCB0SDAXIN|-|-|XOUT|XOUT|-|P1.6/UCB0SCL|P1.6/UCB0SCL|,主机在不停地发数据给从机，时钟为1MHz,例2：,#include主机unsignedcharTXData;unsignedcharTXByteCtr;intmain(void)WDTCTL=WDTPW+WDTHOLD;P1SEL|=BIT6+BIT7;P1SEL2|=BIT6+BIT7;UCB0CTL1|=UCSWRST;UCB0CTL0=UCMST+UCMODE_3+UCSYNC;UCB0CTL1=UCSSEL_2;UCB0BR0=10;UCB0BR1=0;UCB0I2CSA=0 x48;UCB0CTL1,while(1)TXByteCtr=1;while(UCB0CTL1,#pragmavector=USCIAB0TX_VECTOR_interruptvoidUSCIAB0TX_ISR(void)if(TXByteCtr)/CheckTXbytecounterUCB0TXBUF=TXData;/LoadTXbufferTXByteCtr-;/DecrementTXbytecounterelseUCB0CTL1|=UCTXSTP;/I2CstopconditionIFG2/ExitLPM0,#include从机volatileunsignedcharRXData;intmain(void)WDTCTL=WDTPW+WDTHOLD;P1SEL|=BIT6+BIT7;P1SEL2|=BIT6+BIT7;UCB0CTL1|=UCSWRST;UCB0CTL0=UCMODE_3+UCSYNC;UCB0I2COA=0 x32;UCB0CTL1,#pragmavector=USCIAB0TX_VECTOR_interruptvoidUSCIAB0TX_ISR(void)RXData=UCB0RXBUF;_bic_SR_register_on_exit(CPUOFF);,例3：,TM1638的各个管脚功能说明：,矩阵键盘的读取,LED数码管显示,数码管,显示的数字形式,七段半导体数码显示器(LED),数码管结构,a,b,c,d,e,f,g,h,hgfedcba,高电平,共阴极,hgfedcba,hgfedcba,R8,com,D7D6D5D4D3D2D1D0,段码,字形码,段码：为了显示数字或字符，必须对数字或字符进行编码。七段数码管加上一个小数点，共计8段,因此为LED显示器提供的编码正好是一个字节。这些代码通过各段的亮与灭来显示不同字型的，因此称之为段码。,共阴极,D7D6D5D4D3D2D1D0,hgfedcba,hgfedcba,hgfedcba,段码与字形的关系,0 x3f,0 x06,0 x5b,0 x4f,0 x66,0 x6d,0123450 x7d,0 x07,0 x7f,0 x6f,0 x77,0 x7c,6789AB0 x39,0 x5e,0 x79,0 x71,0 x00CDEF无显示,+5V,hgfedcba,共阳极,com,R8,abcdefgh某段为低电平时该段点亮发光,D7D6D5D4D3D2D1D0,段码,共阳极,段码与字形的关系,0 xc0,0 xf9,0 xa4,0 xb0,0 x99,0 x92,0123450 x82,0 xf8,0 x80,0 x90,0 x88,0 x83,6789AB0 xc6,0 xa1,0 x86,0 x8e,0 xffCDEF无显示,动态显示,动态显示的特点：是将所有位数码管的段选线并联在一起，由位选线控制是哪一位数码管有效。当需要显示数字或字符时，将数码管轮流点亮，即动态扫描显示。所谓动态扫描显示：即轮流向各位数码管送出字形码和相应的位选，利用发光管的余辉和人眼视觉暂留作用，使人的感觉好像各位数码管同时都在显示。,图八位LED动态显示器电路,#includeTM1638.hconstuint8_ttab2=0 x3F,0 x06,0 x5B,0 x4F,0 x66,0 x6D,0 x7D,0 x07,0 x7F,0 x6F,0 x77,0 x7C,0 x39,0 x5E,0 x79,0 x71;voidTM1638_Write(unsignedcharDATA)/写数据函数unsignedchari;P3DIR|=BIT5;for(i=0;i=1;,unsignedcharTM1638_Read(void)/读数据函数unsignedchari;unsignedchartemp=0;P3DIR,voidWrite_COM(unsignedcharcmd)/发送命令字P3OUT|=BIT4;P3OUT|=BIT2;P3OUT,unsignedcharRead_key(void)unsignedcharc4;unsignedintkey_value=0 x00;unsignedinti;P3OUT|=BIT2;P3OUT,elseif(c0,elseif(c1,voidWrite_DATA(unsignedcharadd,unsignedcharDATA)/指定地址写入数据Write_COM(0 x44);P3OUT,voidWrite_allLED(unsignedcharDATA)unsignedchari;Write_COM(0 x8F);/显示控制Write_COM(0 x40);/数据命令P3OUT,#ifndef_TM1638_H#define_TM1638_H#includemsp430f6638.h#include#defineCPU_F(double)20000000)#define_delay_us(x)_delay_cycles(long)(CPU_F*(double)x/1000000.0)#define_delay_ms(x)_delay_cycles(long)(CPU_F*(double)x/1000.0)#defineDIO_high(P3OUT|=BIT5)#defineDIO_low(P3OUT#endif,参考程序代码,#includeTM1638.h#includemsp430f6638.huint8_tnum8;/各个数码管显示的值uint8_tled_flag8;constuint8_ttab=0 x3F,0 x06,0 x5B,0 x4F,0 x66,0 x6D,0 x7D,0 x07,0 x7F,0 x6F,0 x77,0 x7C,0 x39,0 x5E,