Functional differences of three clocks of MSP430 microcontroller

The system clocks of the MSP430 microcontroller are divided into three types: MCLK, SMCLK and ACLK. One, several or all of them can be turned off as needed. 
The units in the MCU that require clocks include the CPU and some on-chip peripherals. The functional differences of the three clocks are as follows:
1. MCLK: Main system clock, a clock specifically provided for CPU operation. The higher the MCLK frequency is configured, the faster the CPU executes. Although the faster the CPU speed, the higher the power consumption, but the high-frequency MCLK can make the CPU work for a shorter time. Therefore, the correct low-power design is not to reduce MCLK as much as possible, but to turn off MCLK immediately when the CPU is not in use. In most applications, the time required for CPU calculation is very short, so the method of intermittently turning on MCLK (waking up the CPU) has a very obvious energy-saving effect.
2. SMCLK: Sub-system clock, which is specifically designed to provide services for some on-chip peripherals that require high-speed clocks, such as timers and ADC sampling. When the CPU is in sleep mode, as long as SMCLK is on, the timer and ADC can still work (usually after the on-chip peripherals have completed their work, an interrupt is triggered to wake up the CPU to do subsequent work).
3.ACLK: Auxiliary Clock. The frequency of the auxiliary clock is very low, so even if it is always on, the power consumption is not large. Of course, it can also be turned off. The auxiliary clock can be supplied to those on-chip peripherals that only need a low-frequency clock, such as the LCD controller. It can also be used to generate a beat time base and cooperate with the timer to intermittently wake up the CPU.