How can I use External Crystal(clock) in MSP430F1611

Hi Mogano,
Have you tried using the code examples located in product page www.ti.com/.../toolssoftware ) or Resource Explorer (found under 'View' in CCS Desktop, or at dev.ti.com)?

It looks like you are wanting to use high frequency crystal, XT2, is that correct?

If so, there is an example called "fet140)clks.c" that uses the XT2.

For ease, I post the code here, but do go check out the examples at one of the locations I mentioned above.

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//******************************************************************************
//  MSP-FET430P140 Demo - Basic Clock, Output Buffered SMCLK, ACLK and MCLK
//
//  Description: Output buffered MCLK, SMCLK and ACLK.
//  ACLK = LFXT1 = 32768, MCLK = DCO Max, SMCLK = XT2
//  //* XTAL's REQUIRED - NOT INSTALLED ON FET *//
//  //* Min Vcc required varies with MCLK frequency - refer to datasheet *//	
//
//                MSP430F149
//            -----------------
//        /|\|              XIN|-
//         | |                 | 32k
//         --|RST          XOUT|-
//           |                 |
//           |            XT2IN|-
//           |                 | XTAL (455k - 8Mhz)
//           |RST        XT2OUT|-
//           |                 |
//           |             P5.4|-->MCLK = DCO Max
//           |             P5.5|-->SMCLK = XT2
//           |             P5.6|-->ACLK = 32kHz
//
//  M. Buccini
//  Texas Instruments Inc.
//  Feb 2005
//  Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.21A
//******************************************************************************

#include <msp430.h>

int main(void)
{
  WDTCTL = WDTPW +WDTHOLD;                  // Stop Watchdog Timer
  DCOCTL = DCO0 + DCO1 + DCO2;              // Max DCO
  BCSCTL1 = RSEL0 + RSEL1 + RSEL2;          // XT2on, max RSEL
  BCSCTL2 |= SELS;                          // SMCLK = XT2
  P5DIR |= 0x70;                            // P5.6,5,4 outputs
  P5SEL |= 0x70;                            // P5.6,5,5 options

  while(1)
  {
  }
}

Thank you Cameron
In my micro controller , there is an external crystal. is that name xt2?

Are you using a Target board or EVM? Or is this a custom design.

The XT2 is usually the high frequency crystal, but looks  like it will default to the LFXT (low frequency 32kHz crystal) if the high frequency crystal is not present.