The code that is below is from the ti code sample for msp430g2553.
It says in the comment that external watch crystal installed on Xin and Xout is required for ACLK.
What I am trying to ask is does this program use an external clock or not?
The code shows an O/P on P1.0/ACLK. But where are the PSEL for Xin and Xout?
If this is not the code for the external clock, what is? The readme text file has no description of the .c files.
//******************************************************************************
// MSP430G2xx3 Demo - Basic Clock, Output Buffered clocks with preloaded DCO
// calibration constants for BCSCTL1 and DCOCTL.
//
// Description: Buffer ACLK on P2.0, default SMCLK(DCO) on P1.4 and MCLK/10 on
// P1.1. DCO is software selectable to 1, 8, 12, or 16Mhz using calibration
// contstants in INFOA.
//
// ACLK = LFXT1 = 32768, MCLK = SMCLK = Selectable at 1, 8, 12 or 16Mhz
// //* External watch crystal installed on XIN XOUT is required for ACLK *//
//
// MSP430G2xx3
// -----------------
// /|\| XIN|-
// | | | 32kHz
// --|RST XOUT|-
// | |
// | P1.4/SMCLK|-->SMCLK = Default DCO
// | P1.1|-->MCLK/10 = DCO/10
// | P1.0/ACLK|-->ACLK = 32kHz
//
// D. Dang
// Texas Instruments Inc.
// December 2010
// Built with IAR Embedded Workbench Version: 3.42A
//******************************************************************************
#include <msp430g2553.h>
void main(void)
{
WDTCTL = WDTPW +WDTHOLD; // Stop Watchdog Timer
if (CALBC1_1MHZ ==0xFF || CALDCO_1MHZ == 0xFF)
{
while(1); // If calibration constants erased
// do not load, trap CPU!!
}
//1Mhz
BCSCTL1 = CALBC1_1MHZ; // Set range
DCOCTL = CALDCO_1MHZ; // Set DCO step + modulation */
/* //8Mhz
BCSCTL1 = CALBC1_8MHZ; // Set range
DCOCTL = CALDCO_8MHZ; // Set DCO step + modulation */
/* //12Mhz
BCSCTL1 = CALBC1_12MHZ; // Set range
DCOCTL = CALDCO_12MHZ; // Set DCO step + modulation*/
/* //16Mhz
BCSCTL1 = CALBC1_16MHZ; // Set range
DCOCTL = CALDCO_16MHZ; // Set DCO step + modulation*/
P1DIR |= 0x13; // P1.0,1 and P1.4 outputs
P1SEL |= 0x11; // P1.0,4 ACLK, SMCLK output
while(1)
{
P1OUT |= 0x02; // P1.1 = 1
P1OUT &= ~0x02; // P1.1 = 0
}
}
