Low power modes can drastically reduce power consumption, going from around a hundred microamps in active mode to under a microamp (or tenths of a microamp) in the 3.x and 4.x low power modes.

• Use the following command to enter the x mode, where x = 0,1,2,3,4,3.5,or 4.5:

_bis_SR_register( GIE | LPMx_bits ); bis = bit set

• To exit LPMx use the following command inside the Interrupt Service Routine ISR, where x = 0,1,2,3,4,3.5,or 4.5 :

__bic_SR_register_on_exit(LPMx_bits ); bic = bit clear

• Choose the appropriate LPM that suits your application. For example, if you use the SPI communication, you need a clock. As result, you have to choose the LPM where the clock source for your SPI is enabled.
• To support low power design, configure all unused pins as an input with pull down resistor to prevent them from floating.

• Be aware of the interrupts priorities for the MCU that you are working on.
• There are specific interruptible ports. Not all ports of the chip are interruptible.

For port interrupts:

• If the interrupt will fire when the port status changed from Low to High, you should configure the port to be pulled down.
• If the interrupt will fire when the port status changed from high to low, you should configure the port to be pulled up.

• Interrupt : https://training.ti.com/msp430-workshop-series-5-12-interrupts?cu=1135311
• Low-Power Optimization : https://training.ti.com/msp430-workshop-series-7-12-low-power-optimization?cu=1135311