Forum Post: Internal LF/LP oscillator for MCLK?

Hi everybody,

I try to use the internal 12 kHz LF/LP oscillator for MCLK but it won't work. The DCO (1.1 MHz default) is always selected instead.

I use an MSP430F2013 on a LaunchPad. The test code is:

    .global    _main                  ; define entry point
_main
    mov.w   #__STACK_END,SP          ; Initialize stackpointer
    mov.w   #WDTPW|WDTHOLD,&WDTCTL   ; Stop watchdog timer

    ;12 kHz operation using VLOCLK
    mov.b    #LFXT1S_2,&BCSCTL3      ;12 kHz LF/LP oscillator for VLOCLK
    mov.b    #SELM_3,&BCSCTL2        ;VLOCLK -> MCLK (does not change anything)
    bis.b    #SCG0,SR               ;Switch DCO off (not necessary for this test)
    bis.b    #BIT0,&P1DIR            ;P1.0 test output
Loop12k
    bis.b    #BIT0,&P1OUT            ;Test  Should toggle with 1.2 kHz approx,
    bic.b    #BIT0,&P1OUT            ;Test  but toggles with 110 kHz approx.
    jmp      Loop12k                 ;10 cycles per loop

When stopped after initialisation the registers show as intended (yellow: changed from PUC)

I tried and experimented, googled and searched in this forum but did not find any hint.

Thanks in advance

Uwe