MSP430F47167: deactivating XT1, only use DCO and XT2

OK, than I have to use an oscillator on XT1 as well.

I added a 3,6 MHz crystal to XT1, the 16 MHz resonator on XT2 is still present. For debugging, the clocks MCLK, ACLK and SMCL are put out on the corresponding pins.

The test code at the end of this post was used

I measured the following frequencies:
ACLK: 3,6 MHz -> OK
SMCLK: 16 MHz -> OK
MCLK: 7,2 MHz -> FAILURE, this is still the DCO clock, not XT2 as coded

Also tried it with

FLL_CTL1 = SELM_A | SELS;     //MCLK source: XT1, SMCLK source: XT2

which should output the XT1 clock on MCLK, but there is still the DCO clock.



I have absolutely no idea what is going wrong

#include <msp430.h> 

/*
 * main.c
 */
int main(void) {
    WDTCTL = WDTPW | WDTHOLD;	// Stop watchdog timer

    SCFQCTL = 0b00000001;   //N = 1
    SCFI0 = FN_2;           //DCO range control: 001x 2 to 17.9 MHz,

    FLL_CTL0 = XTS_FLL;             //LFXT1: High frequency mode
    FLL_CTL1 = SELM_XT2 | SELS;     //MCLK source: XT2, SMCLK source: XT2
    FLL_CTL2 = XT2S_2;              //XT2 range select: 3 to 16-MHz crystal or resonator


    //output MCLK, SCLK and ACLK for external meassurement
    P1DIR |= BIT1 | BIT4 | BIT5;   //Output: P1.1, P1.4,P1.5
    P1SEL |= BIT1 | BIT4| BIT5;   //special function: P1.1(MCLK), P1.4(SMCLK), P1.5(ACLK)

    //infinite loop
    while(1)
    {
        ;
    }
	return 0;
}