MSP430F5436A: MSP430F5xx : XT1OFF bit for HF part or HF and LF parts of XT1

Hello Mitch,

Please see the register definition of USCSTL6 where the XT1OFF bit is described in the MSP430F5xxx and MSP430F6xxx User Guide. 

Hello Jace,

I quoted SLAU208 which is the user guide of MSP430F5xxx!

The exact sentence is :

XT1 off. This bit turns off the XT1.
0b = XT1 is on if XT1 is selected via the port selection and XT1 is not in bypass
mode of operation.
1b = XT1 is off if it is not used as a source for ACLK, MCLK, or SMCLK or is not
used as a reference source required for FLL operation.

But from the sentence I do not understand if it turns only the HF or both part of XT1.

The XT1off bit is not represented in figure 5-1

Hello,

Do not look at F2xxx UG as it is not relevant to F5xxx parts.

As you can see from the register definition I pointed to, you will see that XTS bit (mode select) is a different bit that chooses if XT1 is in LF or HF mode. XT1OFF Bit controls whether XT1 is off as it states (with the exceptions as well). XT1OFF is not dependant on XTS (Mode select) bit. 

Hello,

So to do simple, do I need to set XT1OFF to 0 or to 1 to use the low frequency crystal of XT1?

Hello,

I will follow your recommandation but it is amazing because with XT1OFF = 0 or with XT1OFF=1 I did not find any difference... same current consumption, same frequency for ACLK, same AC and DC amplitude for Xout