MSP430FR5969: msp430fr5969 development board

From the resource explorer i downloaded an example program named msp430fr59xx_cs_04.c

based on this program crystal oscillator worked, creating a one second led toggle,

I changed DCO frequency to 4Mhz which creates 2 second delay

Then i selected HFXT of 4Mhz for MCLK now when i checked it creates a delay of 335 seconds.

#include <msp430.h>

int main(void)
{
WDTCTL = WDTPW | WDTHOLD;

// Configure GPIO
P1OUT = 0;
P1DIR = BIT0; // For LED

P2DIR |= BIT0;
P2SEL0 |= BIT0; // Output ACLK
P2SEL1 |= BIT0;

P3DIR |= BIT4;
P3SEL0 |= BIT4; // Output SMCLK
P3SEL1 |= BIT4;

PJSEL0 |= BIT4 | BIT5 | BIT6 | BIT7; // For XT1 and XT2

// Disable the GPIO power-on default high-impedance mode to activate
// previously configured port settings
PM5CTL0 &= ~LOCKLPM5;

CSCTL0_H = CSKEY >> 8; // Unlock CS registers
CSCTL1 = DCOFSEL_4; // Set DCO to 8MHz
CSCTL2 = SELA__LFXTCLK | SELS__HFXTCLK | SELS__HFXTCLK;
CSCTL3 = DIVA__1 | DIVS__1 | DIVM__1; // Set all dividers to 1
CSCTL4 |= LFXTDRIVE_0 | HFXTDRIVE_0;
CSCTL4 &= ~(LFXTOFF | HFXTOFF);
/* do
{
CSCTL5 &= ~(LFXTOFFG | HFXTOFFG); // Clear XT1 and XT2 fault flag
SFRIFG1 &= ~OFIFG;
}while (SFRIFG1&OFIFG); // Test oscillator fault flag
CSCTL0_H = 0; */ // Lock CS registers

while (1) {
P1OUT ^= 0x01; // Toggle LED
__delay_cycles(8000000); // Wait 8,000,000 CPU Cycles
}
}

does MCLK support HFXT

Hi Bruce,

I uncommented to loop and it worked fine, but in my design, I am not using an external low-frequency oscillator so I commented the loop and the external crystal is not providing the required clock pulse is it possible that this microcontroller can work only with external high-frequency oscillator

Data sheet (SLAS704F) Table 5-5 claims the HFXT runs up to 24MHz. My Launchpad even has a site (Y1) for a high-speed crystal.

Clearing HFXTOFFG (and OFIFG) repeatedly is pretty much required [Ref User GUide (SLAU367P) Sec 3.2.8], since the clock system won't switch clocks until HFXTOFFG is explicitly turned off (and stays off). 

Probing a a crystal oscillator with a scope is notoriously difficult. I suggest routing SMCLK to P3.4 and watching that [Ref data sheet Table .6-57].

Hi Bruce,

My external crystal oscillator is working fine and able to produce desired frequency when i have an external low-frequency oscillator, whereas in my design i not able to use an external low-frequency oscillator, is there a way to make it work without external low frequency oscillator

I think my neuron finally fired -- you don't care about  (indeed expect) an LFXT fault, but it still causes OFIFG to be set.

I haven't tried this combination. But based on UG (SLAU367P) Sec 3.2.8 (specifically "If LFXT is sourcing any system clock..") you should start by something like:

> CSCTL2 = SELA__LFMODCLK | SELS__HFXTCLK | SELS__HFXTCLK; // ACLK=something which is not LFXT

There's also CSCTL5:ENSTFCNT1=0 [Ref UG Table 3-9], which based on the description turns off the clock-fault logic for LFXT. [I haven't tried it, maybe it works.]