Problem in the USCI Receive Interrupt Operation

[Luniks]

Hi everybody !

I am writing a UART code to communicate between a MSP430-F2350 and my PC and I have a problem with the Receive Interrupt Operation. This is my code :

#include <msp430x23x0.h>

__interrupt void USCI0RX_ISR(void);

void main(void)
{
	unsigned char Tab[7] = {0x48,0x65,0x6C,0x6C,0x6F,0x20,0x21}; // ASCII code
	unsigned int i;
	
	WDTCTL = WDTPW + WDTHOLD;			// Stop WDT
	BCSCTL1 = CALBC1_1MHZ;				// Set DCO
	DCOCTL = CALDCO_1MHZ;
	P3DIR |= 0x40;						// Set P3.6 to output direction
	P3OUT |= 0x40;						// P3.6 to high level (disabled UHF)
	
	P3SEL |= 0x30;						// P3.4,5 = USCI_A0 TXD/RXD
	UCA0CTL1 |= UCSSEL_2;				// SMCLK
	UCA0BR0 = 0x68;						// 1MHz : 9600 Bauds
	UCA0BR1 = 0x00;
	UCA0MCTL = UCBRS0;					// Modulation UCBRSx = 1
	UCA0CTL1 &= ~UCSWRST;				// Initialize USCI state machine
	IE2 |= UCA0RXIE;					// Enable USCI_A0 RX interrupt
	
	for (i=0; i<7; i++)					//---- Sending Hello !
	{
		while (!(IFG2 & UCA0TXIFG));
		UCA0TXBUF = Tab[i];
	}

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

#pragma vector=USCIAB0RX_VECTOR
__interrupt void USCI0RX_ISR(void)
{
	while (!(IFG2 & UCA0TXIFG));
	UCA0TXBUF = UCA0RXBUF;				// Sending the received character
}

When I send my ASCII array before to enter in LPM0 mode I receiced correctly the string "Hello !" on my PC with Hterm. But if I press a key .... no echo in Hterm !

Any ideas ? Thanks ...

 

[bobcat1]

HI

It is bad programming way to place a while loop inside your ISR routine

You can place a SWITCH or IF sentence

You also need to implement a ring buffer for avoid loosing data

All the best

Bobi

The microcontroller specialist

 

[Luniks]

Hi,

Thanks for yours advices ... I take notes ^^.
Do you have any ideas why the program don't go in the interrupt procedure ?

Regards

 

[Luniks]

up ... !!

Luniks.