Hi Raymond, I found the "MSP430x261x_hfxt2.c" code example in MSP430Ware in CCS. This reference combined with the datasheet and User's Guide should get you started. /* --COPYRIGHT--,BSD_EX * Copyright (c) 2012, Texas Instruments Incorporated * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * * Neither the name of Texas Instruments Incorporated nor the names of * its contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * ******************************************************************************* * * MSP430 CODE EXAMPLE DISCLAIMER * * MSP430 code examples are self-contained low-level programs that typically * demonstrate a single peripheral function or device feature in a highly * concise manner. For this the code may rely on the device's power-on default * register values and settings such as the clock configuration and care must * be taken when combining code from several examples to avoid potential side * effects. Also see www.ti.com/grace for a GUI- and www.ti.com/msp430ware * for an API functional library-approach to peripheral configuration. * * --/COPYRIGHT--*/ //****************************************************************************** // MSP430x26x Demo - Basic Clock, MCLK Configured to Operate from XT2 HF XTAL // // Description: Proper selection of an external HF XTAL for MCLK is shown // using HF XT2 OSC. OFIFG is polled until the HF XTAL is stable; only then is // MCLK sourced by XT2. MCLK is buffered on P5.4 and MCLK/10 is on P1.1 driven // by a software loop taking exactly 10 CPU cycles. // ACLK = MCLK = LFXT1 = HF XTAL, SMCLK = default DCO ~1.045MHz // //* XT2 HF XTAL NOT INSTALLED ON FET *// // //* Min Vcc required varies with MCLK frequency - refer to datasheet *// // // MSP430F261x/241x // ----------------- // /|\| XIN|- // | | | // --|RST XOUT|- // | | // | | // | XT2IN|- // | | HF XTAL (400kHz - 16MHz) // | XT2OUT|- // | | // | P1.1|-->MCLK/10 = XT2 HFXTAL/10 // | P5.4/MCLK|-->MCLK = XT2 HFXTAL // // B. Nisarga // Texas Instruments Inc. // September 2007 // Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.42A //****************************************************************************** #include volatile unsigned int i; int main(void) { WDTCTL = WDTPW + WDTHOLD; // Stop WDT P5DIR |= 0x10; // P5.4= output direction P5SEL |= 0x10; // P5.4= MCLK option select P1DIR |= 0x02; // P1.1 = output direction BCSCTL1 &= ~XT2OFF; // Activate XT2 high freq xtal BCSCTL3 |= XT2S_2; // 3 – 16MHz crystal or resonator do { IFG1 &= ~OFIFG; // Clear OSCFault flag for (i = 0xFF; i > 0; i--); // Time for flag to set } while (IFG1 & OFIFG); // OSCFault flag still set? BCSCTL2 |= SELM_2; // MCLK = XT2 HF XTAL (safe) for (;;) // Infinite loop { P1OUT |= 0x02; // P1.1 = 1 P1OUT &= ~0x02; // P1.1 = 0 } } Here's a screenshot of the XT2 section in the datasheet. Regards, James MSP Customer Applications
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