Good afternoon,
I am working on a project and I am interested in utilizing the VLO to turn off and on the msp430fr2311 microcontroller. I found an example code in the documentation for doing this with an external 32khz crystal:
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//******************************************************************************
// MSP430FR231x Demo - Enters LPM3 with ACLK = XT1CLK = 32768Hz.
//
// Description: Configures ACLK to be sourced from XT1 crystal. Enter LPM3 until
// WDT ISR is executed and toggles the LED on P1.0.
//
// MSP430FR2311
// ---------------
// /|\| |
// | | |
// | | XIN(P2.7)|--
// --|RST | ~32768Hz
// | XOUT(P2.6)|--
// | |
// | P1.0|-->LED
//
// Darren Lu
// Texas Instruments Inc.
// July 2015
// Built with IAR Embedded Workbench v6.30 & Code Composer Studio v6.1
//******************************************************************************
#include <msp430.h>
int main(void)
{
WDTCTL = WDT_ADLY_1000; // WDT 1000ms, ACLK, interval timer
SFRIE1 |= WDTIE; // Enable WDT interrupt
P2SEL1 |= BIT6 + BIT7; // P2.0: XOUT; P2.1: XI1
CSCTL4 = SELMS__DCOCLKDIV | SELA__XT1CLK; // MCLK=SMCLK=DCO; ACLK=XT1
// Port Configuration all un-used pins to output low
P1OUT = 0x00;
P2OUT = 0x00;
P1DIR = 0xff;
P2DIR = 0xff;
// Disable the GPIO power-on default high-impedance mode
// to activate previously configured port settings
PM5CTL0 &= ~LOCKLPM5;
do
{
CSCTL7 &= ~(XT1OFFG | DCOFFG); // Clear XT1 and DCO fault flag
SFRIFG1 &= ~OFIFG;
}while (SFRIFG1 & OFIFG); // Test oscillator fault flag
__bis_SR_register(LPM3_bits | GIE); // Enter LPM3
__no_operation(); // For debug
}
// Watchdog Timer interrupt service routine
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=WDT_VECTOR
__interrupt void WDT_ISR(void)
#elif defined(__GNUC__)
void __attribute__ ((interrupt(WDT_VECTOR))) WDT_ISR (void)
#else
#error Compiler not supported!
#endif
{
P1OUT ^= BIT0; // Toggle P1.0 (LED) every 1s
}
How could I edit the code to use the internal VLO as an ACLK source instead.
Regards,
George Fleming