TI中文支持网如何设置相关寄存器？有例程吗？
Hardy Hu：
//******************************************************************************
// MSP430x24x Demo – USCI_B0 I2C Slave TX single bytes to MSP430 Master
//
// Description: This demo connects two MSP430's via the I2C bus. The master
// reads from the slave. This is the slave code. The TX data begins at 0
// and is incremented each time it is sent. An incoming start condition
// is used as a trigger to increment the outgoing data. The master checks the
// data it receives for validity. If it is incorrect, it stops communicating
// and the P1.0 LED will stay on. The USCI_B0 TX interrupt is used to know
// when to TX.
// ACLK = n/a, MCLK = SMCLK = default DCO = ~1.045Mhz
//
// /|\ /|\
// MSP430F249 10k 10k MSP430F249
// slave | | master
// —————– | | —————–
// -|XIN P3.1/UCB0SDA|<-|—+->|P3.1/UCB0SDA XIN|-
// | | | | |
// -|XOUT | | | XOUT|-
// | P3.2/UCB0SCL|<-+—–>|P3.2/UCB0SCL |
// | | | |
//
// B. Nisarga
// Texas Instruments Inc.
// September 2007
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************
#include "msp430x24x.h"
unsigned char TXData;
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P3SEL |= 0x06; // Assign I2C pins to USCI_B0
UCB0CTL1 |= UCSWRST; // Enable SW reset
UCB0CTL0 = UCMODE_3 + UCSYNC; // I2C Slave, synchronous mode
UCB0I2COA = 0x48; // Own Address is 048h
UCB0CTL1 &= ~UCSWRST; // Clear SW reset, resume operation
UCB0I2CIE |= UCSTTIE; // Enable Start condition interrupt
IE2 |= UCB0TXIE; // Enable TX interrupt
TXData = 0xff; // Used to hold TX data
while (1)
{
__bis_SR_register(CPUOFF + GIE); // Enter LPM0 w/ interrupts
}
}
// USCI_B0 Data ISR
#pragma vector = USCIAB0TX_VECTOR
__interrupt void USCIAB0TX_ISR(void)
{
UCB0TXBUF = TXData; // TX data
__bic_SR_register_on_exit(CPUOFF); // Exit LPM0
}
// USCI_B0 State ISR
#pragma vector = USCIAB0RX_VECTOR
__interrupt void USCIAB0RX_ISR(void)
{
UCB0STAT &= ~UCSTTIFG; // Clear start condition int flag
TXData++; // Increment data
}
Hardy Hu：
在www.ti.com//mcu/docs/mcuproductcontentnp.tsp?sectionId=95&familyId=342&tabId=3357
下面的code example中可以下载到更多的相关例程
zhibin li：
回复 Hardy Hu:
我用示波器观察SCL和SDA两根线的波形，在发出开始标志时只有SCL被拉低了，而且不会回到高电平状态，这是怎么回事？
Hardy Hu：
回复 zhibin li:
正常的操作时序是，START发了后SDA先拉低并保持，再是SCL拉低，IIC的数据在SCL的正平区间有效，而且需要在SCL正平区间内，SDA保持稳定。
建议你先断开receiver，看transmitter发送address是否正确，再接上receiver，看收到了什么数据，用示波器抓ACK和后面出错的波形。IIC等同步串行总线是receiver与transmitter双方面交互进行数据传输的，调试需要一步一步走
