请教关于串口的问题

2019-07-25 15:28发布

站内问答 / TI MCU

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我最近在学MSP430F149串口模块，我用的是TI的标准程序，一个字都没改；但是单片机就是不能正常收发数据。而且换了2个了，不知道到底怎么回事，大家能够帮帮我吗。

//******************************************************************************
// MSP-FET430P140 Demo - USART0, Ultra-Low Pwr UART 9600 Echo ISR, 32kHz ACLK
//
// Description: Echo a received character, RX ISR used. In the Mainloop UART0
// is made ready to receive one character with interrupt active. The Mainloop
// waits in LPM3. The UART0 ISR forces the Mainloop to exit LPM3 after
// receiving one character which echo's back the received character.
// ACLK = UCLK0 = LFXT1 = 32768, MCLK = SMCLK = DCO~ 800k
// Baud rate divider with 32768hz XTAL [url=home.php?mod=space&uid=681799]@9600[/url] = 32768Hz/9600 = 3.41 (0003h 4Ah )
// //* An external watch crystal is required on XIN XOUT for ACLK *//
//
// MSP430F149
// -----------------
// /|| XIN|-
// | | | 32kHz
// --|RST XOUT|-
// | |
// | P3.4|----------->
// | | 9600 - 8N1
// | P3.5|<-----------
//
//
// M. Buccini
// Texas Instruments Inc.
// Feb 2005
// Built with IAR Embedded Workbench Version: 3.21A
//******************************************************************************
#include <msp430x14x.h>
void main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P3SEL |= 0x30; // P3.4,5 = USART0 TXD/RXD
ME1 |= UTXE0 + URXE0; // Enable USART0 TXD/RXD
UCTL0 |= CHAR; // 8-bit character
UTCTL0 |= SSEL0; // UCLK = ACLK
UBR00 = 0x03; // 32k/9600 - 3.41
UBR10 = 0x00; //
UMCTL0 = 0x4A; // Modulation
UCTL0 &= ~SWRST; // Initialize USART state machine
IE1 |= URXIE0; // Enable USART0 RX interrupt
// Mainloop
for (;;)
{
_BIS_SR(LPM3_bits + GIE); // Enter LPM3 w/interrupt
while (!(IFG1 & UTXIFG0)); // USART0 TX buffer ready?
TXBUF0 = RXBUF0; // RXBUF0 to TXBUF0
}
}
// UART0 RX ISR will for exit from LPM3 in Mainloop
#pragma vector=UART0RX_VECTOR
__interrupt void usart0_rx (void)
{
_BIC_SR_IRQ(LPM3_bits); // Clear LPM3 bits from 0(SR)
}