请教一个串口的奇怪问题

zhenyu xu

Prodigy 240 points

Other Parts Discussed in Thread: MSP430F2252

先说说我的开发环境：

IAR + 430LaunchPad + msp430F2252目标板。

电路上断开launchpad的J3跳线（VCC保留），连接到目标板上，可以调试，仿真和串口。

问题来了，我写了一段双工的串口程序，结果：可以收到PC端的，却不能发送到PC,怪异的是示波器查看TXD有输出,9600波特率每位约103.5us,应该算标准了，但PC就是收不到，换了几个软件都不行。

我又用launchpad带的G2553试了模拟串口的程序，收发都可以，所以硬件应该没问题

下面把程序贴出来，大家帮我检查一下那里配置错了。其实程序参考例程的。

#include "io430.h"
#include "led.h"

#define UCA0_TXD BIT4
#define UCA0_RXD BIT5

char string1[8]="u hello";
char i;
char j = 0;

void uart_init(void)
{

P3SEL = UCA0_TXD + UCA0_RXD; // P3.4,5 = USCI_A0 TXD/RXD
UCA0CTL1 |= UCSSEL_2; // CLK = ACLK
UCA0BR0 = 0x68; // 1.MHz/9600 = 125
UCA0BR1 = 0x00; //
UCA0MCTL = UCBRS2; // Modulation UCBRSx = 0x04
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI_A0 RX interrupt

}

#pragma vector=USCIAB0TX_VECTOR
__interrupt void USCI0TX_ISR(void)
{
UCA0TXBUF = string1[i++]; // TX next character
//LED_PWR_GRN_BLINK;
if (i == sizeof string1 - 1) // TX over?
{
IE2 &= ~UCA0TXIE; // Disable USCI_A0 TX interrupt

i=0;
}
}

#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{
if (UCA0RXBUF == 'u') // 'u' received?
{
i = 0;
UCA0TXBUF = string1[i++];
//LED_GAME_RED_BLINK;
IE2 |= UCA0TXIE; // Enable USCI_A0 TX interrupt
}
}

我时钟选得smclk = dco =1MHZ

主函数调用

uart_init();
__bis_SR_register(GIE); // interrupts enabled
while(1);

请各位指点下。

12 年多前

0 Bruce Wei 12 年多前

TI__Mastermind 24987 points

楼主你好！

试一下超级终端，参考附件

Hypertrm.7z

0 zhenyu xu 12 年多前回复 Bruce Wei

Prodigy 240 points

试过了，一样不行。我用timer模拟的uart可以工作，所以估计是程序问题

0 Bruce Wei 12 年多前回复 zhenyu xu

TI__Mastermind 24987 points

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*
*******************************************************************************
*
* MSP430 CODE EXAMPLE DISCLAIMER
*
* MSP430 code examples are self-contained low-level programs that typically
* demonstrate a single peripheral function or device feature in a highly
* concise manner. For this the code may rely on the device's power-on default
* register values and settings such as the clock configuration and care must
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* for an API functional library-approach to peripheral configuration.
*
* --/COPYRIGHT--*/
//******************************************************************************
// MSP430G2xx3 Demo - USCI_A0, 9600 UART Echo ISR, DCO SMCLK
//
// Description: Echo a received character, RX ISR used. Normal mode is LPM0.
// USCI_A0 RX interrupt triggers TX Echo.
// Baud rate divider with 1MHz = 1MHz/9600 = ~104.2
// ACLK = n/a, MCLK = SMCLK = CALxxx_1MHZ = 1MHz
//
// MSP430G2xx3
// -----------------
// /|\| XIN|-
// | | |
// --|RST XOUT|-
// | |
// | P1.2/UCA0TXD|------------>
// | | 9600 - 8N1
// | P1.1/UCA0RXD|<------------
//
// D. Dang
// Texas Instruments Inc.
// February 2011
// Built with CCS Version 4.2.0 and IAR Embedded Workbench Version: 5.10
//******************************************************************************
#include <msp430.h>

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
if (CALBC1_1MHZ==0xFF) // If calibration constant erased
{
while(1); // do not load, trap CPU!!
}
DCOCTL = 0; // Select lowest DCOx and MODx settings
BCSCTL1 = CALBC1_1MHZ; // Set DCO
DCOCTL = CALDCO_1MHZ;
P1SEL = BIT1 + BIT2 ; // P1.1 = RXD, P1.2=TXD
P1SEL2 = BIT1 + BIT2 ; // P1.1 = RXD, P1.2=TXD
UCA0CTL1 |= UCSSEL_2; // SMCLK
UCA0BR0 = 104; // 1MHz 9600
UCA0BR1 = 0; // 1MHz 9600
UCA0MCTL = UCBRS0; // Modulation UCBRSx = 1
UCA0CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
IE2 |= UCA0RXIE; // Enable USCI_A0 RX interrupt

__bis_SR_register(LPM0_bits + GIE); // Enter LPM0, interrupts enabled
}

// Echo back RXed character, confirm TX buffer is ready first
#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{
while (!(IFG2&UCA0TXIFG)); // USCI_A0 TX buffer ready?
UCA0TXBUF = UCA0RXBUF; // TX -> RXed character
}