MSP430F149 small system development board implements USART data receiving interrupt

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MSP430F149 small system development board implements USART data receiving interrupt [Copy link]

//******************************************************************************
// MSP-FET430P140 Demo - USART0, Ultra-Low Pwr UART 2400 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 @2400 = 32768Hz/2400 = 13.65 (000Dh)
// //* An external watch crystal is required on XIN XOUT for ACLK *//
//
// MSP430F149
// -----------------
// /|\| XIN|-
// | | | 32kHz
// --|RST XOUT|-
// | |
// | P3.4|----------->
// | | 2400 - 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 = 0x0D; // 32k/2400 - 13.65
UBR10 = 0x00; //
UMCTL0 = 0x6B; // 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=USART0RX_VECTOR
__interrupt void usart0_rx (void)
{
_BIC_SR_IRQ(LPM3_bits); // Clear LPM3 bits from 0(SR)
}

After running the program, when data is sent to the development board, the light on the development board will go out. Then, the serial port debugging assistant will receive the data.