我在使用launch pad msp430g2553芯片做iic开发时，下载的程序是ccs里的例程
// 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 = ~1.2MHz
//
// /|\ /|\
// MSP430G2xx3 10k 10k MSP430G2xx3
// slave | | master
// ----------------- | | -----------------
// -|XIN P1.7/UCB0SDA|<-|---+->|P1.7/UCB0SDA XIN|-
// | | | | |
// -|XOUT | | | XOUT|-
// | P1.6/UCB0SCL|<-+----->|P1.6/UCB0SCL |
// | | | P1.0|--> LED
//
// D. Dang
// Texas Instruments Inc.
// February 2011
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include "msp430g2553.h"
unsigned char TXData;
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR |= BIT0; // P1.0 output
P1SEL |= BIT6 + BIT7; // Assign I2C pins to USCI_B0
P1SEL2|= BIT6 + BIT7; // 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 STT 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
}
同时我在P1.6和P1.7引脚上接了上拉电阻5.1k。然后下载程序，并把示波器接到P1.6和P1.7上，但是无法出现波形？不知道是怎么回事，还有就是P1.6和P1.7的输出电压是不一样的吗？