SMCLK cant drive 2 peripherals?

Dear all,

I am an AVR atmega8 refugee, and msp's clocking scheme seems pretty feature rich (not to mention complex!). I am using MSP430G2 launchpad (g2553). This program uses TImerA, and hardware UART with interrupt. It runs at 1Mhz from DCO. And the peripherals take clock from SMCLK.

The UART just echos whatever it receives. The timer generate 500ms delay, and toggles the red and green leds on board

http://pastebin.com/yApLyFbu

The problem is, I can only have one peripheral at a time using the SMCLK. If I have the above code running exactly as it is, the timer will correctly run and toggle the leds as expected, but the UART echo wont work.

If I comment out line 8,

TACTL = TASSEL1; //set SMCLK as source - TASSELx = 10

(which means timer is not turned-on at all, right?) then UART echo works.

So is it something wrong with my code, or is it like that with the MSP430G2253 ?

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Thanks and Regards,

Aurabindo