CCS/MSP430F248: MSP430F248 oscillator error problem

Hi Kevin,

Do you happen to know what value the XT2Sx bits in the BCSCTL3 register are set to?
I see you have 22pF caps and 1M resistor in the circuit.
Is this what the crystal manufacturer recommends?

Hi Dennis,
Thank you for your reply.
The caps and resistor is manufacturer recommends. I connect the crystal to XT1 and config is as follows:
BCSCTL1 = 0xc8; //2M

BCSCTL2 = 0xc0; //2M

BCSCTL3 = 0x10;

do
{
IFG1 &= ~OFIFG; // Clear OSCFault flag
delay(1000);
}
while (IFG1&OFIFG); // OSCFault flag still set?

Kevin

Hi,
Any suggestions? Thanks.
Kevin

Hi Dennis,
Now a new discovery is that when I turn on the power and write watchdog whthout right security key, a PUC is generated, and because the PUC switches the LFXT1 to LF mode, so crystal oscillation does not start. And power consumption is the same size as in case of mentioned earlier。
But I still don't know why the program doesn't continue to execute, but repeatedly in puc.

Kevin

Hi Kevin,

As you mentioned - the PUC signal can turn off your crystal oscillator as mentioned in page 33, section 2.2.13 of the MSP430Fx2xx Family User's Guide:

"The oscillator fault signal warns of a possible error condition with the crystal oscillator. The oscillator fault

can be enabled to generate an NMI interrupt by setting the OFIE bit. The OFIFG flag can then be tested

by NMI the interrupt service routine to determine if the NMI was caused by an oscillator fault.

A PUC signal can trigger an oscillator fault, because the PUC switches the LFXT1 to LF mode, therefore

switching off the HF mode. The PUC signal also switches off the XT2 oscillator."

 

-Chris

Hi Chris,
Thank you for reply.

What perplexed me was the condition which PUC would occur repeatedly. I've checked the conditions as follows in section 2.1 of the MSP430Fx2xx Family User's Guide:

A POR is a device reset. A POR is only generated by the following three events:
• Powering up the device(1)
• A low signal on the RST/NMI pin when configured in the reset mode(2)
• An SVS low condition when PORON = 1.(3)
A PUC is always generated when a POR is generated, but a POR is not generated by a PUC. The
following events trigger a PUC:
• A POR signal(4)
• Watchdog timer expiration when in watchdog mode only(5)
• Watchdog timer security key violation(6)
• A Flash memory security key violation(7)
• A CPU instruction fetch from the peripheral address range 0h to 01FFh(8)

And i have check the condition as follows:
(1)The power supply is stable.
(2)External Watchdog takes effect every 30 seconds（give a reset signal）.
(3) And there is no flash operation.
(4) Enough time for variable initialization.
(5)The first instruction of the main function is "WDTCTL = WDTPW + WDTHOLD; "(after cstartup.s43)

Is there a condition that cause PUC repeatedly? And only poweroff can return to normal？

Kevin