MSP430F249: UART RX is not working

Can you share your code?

//******************************************************************************
// MSP430x24x Demo - USCI_A1, Ultra-Low Pwr UART 9600 Echo ISR, 32kHz ACLK
//
// Description: Echo a received character, RX ISR used. Normal mode is LPM3,
// USCI_A1 RX interrupt triggers TX Echo.
// ACLK = BRCLK = LFXT1 = 32768Hz, MCLK = SMCLK = DCO ~1.045Mhz
// Baud rate divider with 32768Hz XTAL @9600 = 32768Hz/9600 = 3.41
// => UCBRx = 0x03; In UCA1MCTL: UCBRSx = round(0.41*8) = 0x03
// //* An external watch crystal is required on XIN XOUT for ACLK *//
//
// MSP430F249
// -----------------
// /|\| XIN|-
// | | | 32kHz
// --|RST XOUT|-
// | |
// | P3.6/UCA1TXD|------------>
// | | 9600 - 8N1
// | P3.7/UCA1RXD|<------------
//
// B. Nisarga
// Texas Instruments Inc.
// September 2007
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A
//******************************************************************************
#include <msp430.h>

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
P1DIR = 0xFF; // All P1.x outputs
P1OUT = 0; // All P1.x reset
P2DIR = 0xFF; // All P2.x outputs
P2OUT = 0; // All P2.x reset
P3SEL = 0x0C0; // P3.6,7 = USCI_A1 TXD/RXD
P3DIR = 0xFF; // All P3.x outputs
P3OUT = 0; // All P3.x reset
P4DIR = 0xFF; // All P4.x outputs
P4OUT = 0; // All P4.x reset
P5DIR = 0xFF; // All P5.x outputs
P5OUT = 0; // All P5.x reset
P6DIR = 0xFF; // All P6.x outputs
P6OUT = 0; // All P6.x reset

UCA1CTL1 |= UCSSEL_1; // CLK = ACLK
UCA1BR0 = 0x03; // 32kHz/9600 = 3.41
UCA1BR1 = 0x00; //
UCA1MCTL = UCBRS1 + UCBRS0; // Modulation UCBRSx = 3
UCA1CTL1 &= ~UCSWRST; // **Initialize USCI state machine**
UC1IE |= UCA1RXIE; // Enable USCI_A1 RX interrupt

__bis_SR_register(LPM3_bits + GIE); // Enter LPM3, interrupts enabled
}

// Echo back RXed character, confirm TX buffer is ready first
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=USCIAB1RX_VECTOR
__interrupt void USCI1RX_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(USCIAB1RX_VECTOR))) USCI1RX_ISR (void)
#else
#error Compiler not supported!
#endif
{
while (!(UC1IFG&UCA1TXIFG)); // USCI_A1 TX buffer ready?
UCA1TXBUF = UCA1RXBUF; // TX -> RXed character
}

Have you reset (or power-cycled) the board since you programmed it? As I recall, the FET-Pro software leaves the device in Reset unless you check a box somewhere.

Hi Swarna,

Maybe you can check the difference betwwen the one compiled by IAR, and the one you read out from FET tool.

If it is the same, I suspect whether you have let the device enter some mode which are not running the application code. For eaxmple, reset mode, or bsl mode.

B.R.

Sal

Hi,

The hex there is no change. 

I haven't done any crystal settings. Is this the reason the application is not getting any clk? 

Can you please share the code to configure. I tried with some examples but not successful. 

Hi Swarna,

Swarna Latha said:

The hex there is no change. 

So, is it normal when you use IAR debug mode and then exit debug mode and reset the device?

Swarna Latha said:

I haven't done any crystal settings. Is this the reason the application is not getting any clk? 

The example you share has configured the CLK. 

Maybe you can use internal clock rather than the ACLK for the uart, the reference code is below:

https://dev.ti.com/tirex/explore/node?node=A__AKlljD0-u6GH-hOGGBHFtg__msp430ware__IOGqZri__LATEST 

B.R.

Sal