MSP430FR5739: MSP430FR5739 XT1CLK

Part Number: MSP430FR5739

hello all.

i am simply trying to work with external  XIN crystal mode of 20MHz value .

i did the below setting of the  CS Registers but from my testing  i get MCLK  as 5MHz and i  don't understand where is

deviation of 4  as i expecting to get the 20MHZ.

int main(void)
{
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
CSCTL0_H = 0xA5;
CSCTL1 |= DCORSEL + DCOFSEL1;              // DCO on 16 MHz for MSP DCORSEL = 1 , DCOFSEL = 00 
CSCTL2 = SELA_0 + SELS_0 + SELM_0;      // set  ACLK = SMCLK = MCLK    source  from  XT1CLK
CSCTL3 = DIVA_0 + DIVS_0 + DIVM_0;         // set all dividers /1
CSCTL4 = XTS + XT1DRIVE0 + XT1DRIVE1 ;   // XT1  setting  to High-frequency mode , Maximum drive capability
CSCTL5 &= ~XT1OFFG;

PJSEL0 |= BIT4;          // setting ports to XIN and XOUT pins
PJSEL1 &= ~BIT4;