《MSP430I2C通信》PPT课件.ppt

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1、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START

2、 2.在时钟线高电平时，数据线上升沿代表了停止位STOP 3.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。,/| /| MSP430F6638 100k 100k MSP430F6638 slave | | master - | | - |XIN P8.5/UCB0SDA| |P8.5/UCB0SDA XIN|- | | | | | |XOUT | | | XOUT|- | P8.6/UCB0SCL|P8.6/UCB0S

3、CL | | | | |,主机在不停地发数据给从机，时钟为1MHz,例1：,#include unsigned char TXData; unsigned char TXByteCtr; void main(void) WDTCTL = WDTPW + WDTHOLD; / Stop WDT P8SEL |= BIT5+BIT6; / Assign P8.5 to UCB0SDA and UCB0SCL P8DIR |= BIT6; / P8.6 to UCB0SCL UCB0CTL1 = UCSSEL_2 + UCSWRST; / Use SMCLK, keep SW reset UCB0C

4、TL0 = UCMST + UCMODE_3 + UCSYNC; / I2C Master, synchronous mode UCB0BR0 = 10; UCB0BR1 = 0; UCB0I2CSA = 0 x48; / Slave Address is 048h UCB0CTL1 / Increment data byte ,主机,#pragma vector = USCI_B0_VECTOR _interrupt void USCI_B0_ISR(void) switch(_even_in_range(UCB0IV,12) case 0: break; / Vector 0: No in

5、terrupts case 2: break; / Vector 2: ALIFG case 4: break; / Vector 4: NACKIFG case 6: break; / Vector 6: STTIFG case 8: break; / Vector 8: STPIFG case 10: break; / Vector 10: RXIFG case 12: / Vector 12: TXIFG if (TXByteCtr) / Check TX byte counter UCB0TXBUF = TXData; / Load TX buffer TXByteCtr-; / De

6、crement TX byte counter else UCB0CTL1 |= UCTXSTP; / I2C stop condition UCB0IFG ,#include volatile unsigned char RXData; void main(void) WDTCTL = WDTPW + WDTHOLD; / Stop WDT P8SEL |= BIT5+BIT6; / Assign P8.5/6 to UCB0SDA and UCB0SCL UCB0CTL1 |= UCSWRST; / Enable SW reset UCB0CTL0 = UCMODE_3 + UCSYNC;

7、 / I2C Slave, synchronous mode UCB0I2COA = 0 x32; / Own Address is 032h UCB0CTL1 / Enter LPM0, enable interrupts ,从机,#pragma vector = USCI_B0_VECTOR _interrupt void USCI_B0_ISR(void) switch(_even_in_range(UCB0IV,12) case 0: break; / Vector 0: No interrupts case 2: break; / Vector 2: ALIFG case 4: br

8、eak; / Vector 4: NACKIFG case 6: break; / Vector 6: STTIFG case 8: break; / Vector 8: STPIFG case 10: / Vector 10: RXIFG RXData = UCB0RXBUF; / Get RX data _bic_SR_register_on_exit(LPM0_bits); / Exit LPM0 break; case 12: break; / Vector 12: TXIFG default: break; ,/| /| MSP430G2xx3 100k 100k MSP430G2x

9、x3 slave | | master - | | - -|XIN P1.7/UCB0SDA |P1.7/UCB0SDA XIN|- | | | | -|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 unsigned char TXData; unsigned char TXByteCtr; int main(void) WDTCTL = WDTPW + WDTHOLD; P1SEL |= BIT6 + BIT7; P1SEL2|= BIT6 + BIT7;

10、 UCB0CTL1 |= UCSWRST; UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; UCB0CTL1 = UCSSEL_2 ; UCB0BR0 = 10; UCB0BR1 = 0; UCB0I2CSA = 0 x48; UCB0CTL1 ,while (1) TXByteCtr = 1; while (UCB0CTL1 ,#pragma vector = USCIAB0TX_VECTOR _interrupt void USCIAB0TX_ISR(void) if (TXByteCtr) / Check TX byte counter UCB0TXBUF =

11、 TXData; / Load TX buffer TXByteCtr-; / Decrement TX byte counter else UCB0CTL1 |= UCTXSTP; / I2C stop condition IFG2 / Exit LPM0 ,#include 从机 volatile unsigned char RXData; int main(void) WDTCTL = WDTPW + WDTHOLD; P1SEL |= BIT6 + BIT7; P1SEL2|= BIT6 + BIT7; UCB0CTL1 |= UCSWRST; UCB0CTL0 = UCMODE_3

12、+ UCSYNC; UCB0I2COA = 0 x32; UCB0CTL1 ,#pragma vector = USCIAB0TX_VECTOR _interrupt void USCIAB0TX_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,h g f e d c b a,高电平,共阴极,h g f e d c b a,h g f

13、e d c b a,R8,com,D7 D6 D5 D4 D3 D2 D1 D0,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,D7 D6 D5 D4 D3 D2 D1 D0,h g f e d c b a,h g f e d c b a,h g f e d c b a,段码与字形的关系,0 x3f , 0 x06 , 0 x5b , 0 x4f , 0 x66 , 0 x6d , 0 1 2 3 4 5 0 x7d , 0 x

14、07 , 0 x7f , 0 x6f , 0 x77 , 0 x7c , 6 7 8 9 A B 0 x39 , 0 x5e , 0 x79 , 0 x71 , 0 x00 C D E F 无显示,+5V,h g f e d c b a,共阳极,com,R8,a b c d e f g h 某段为低电平时 该段点亮发光,D7 D6 D5 D4 D3 D2 D1 D0,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 , 0 1 2 3 4 5 0 x82 , 0 xf8 , 0 x80 , 0 x90 , 0 x88 ,

15、 0 x83 , 6 7 8 9 A B 0 xc6 , 0 xa1 , 0 x86 , 0 x8e , 0 xff C D E F 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,#include TM1638.h const uint8_t tab2 = 0 x3F,0 x06,0 x5B,0 x4F,0 x66,

16、0 x6D,0 x7D,0 x07,0 x7F,0 x6F,0 x77,0 x7C,0 x39,0 x5E,0 x79,0 x71; void TM1638_Write(unsigned char DATA) /写数据函数 unsigned char i; P3DIR |= BIT5; for(i=0;i=1; ,unsigned char TM1638_Read(void) /读数据函数 unsigned char i; unsigned char temp=0; P3DIR ,void Write_COM(unsigned char cmd) /发送命令字 P3OUT |= BIT4; P

17、3OUT |= BIT2; P3OUT ,unsigned char Read_key(void) unsigned char c4; unsigned int key_value=0 x00; unsigned int i; P3OUT |= BIT2; P3OUT ,else if(c0 ,else if(c1 ,void Write_DATA(unsigned char add,unsigned char DATA) /指定地址写入数据 Write_COM(0 x44); P3OUT ,void Write_allLED(unsigned char DATA) unsigned char

18、 i; Write_COM(0 x8F);/显示控制 Write_COM(0 x40); /数据命令 P3OUT ,#ifndef _TM1638_H #define _TM1638_H #include msp430f6638.h #include #define CPU_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) #define D

19、IO_high(P3OUT |= BIT5) #define DIO_low(P3OUT #endif,参考程序代码,#include TM1638.h #include msp430f6638.h uint8_t num8; /各个数码管显示的值 uint8_t led_flag8; const uint8_t tab = 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;,void init_port(void) P3DIR |= BIT5; P3DIR |= BIT4 + BIT2; P1DIR |= BIT0; / ACLK set out to pins P1SEL |= BIT0; ,void main(void) unsigned int i = 0; unsigned char count; WDTCTL = WDTPW+WDTHOLD; init_port(); init_TM1638();,while(1) i=Read_key(); if(i0;count-) numcount = numcount-1; ,