A block diagram is a diagram of a system where the principal parts or functions are represented by blocks connected by lines that shows the relationships of the blocks. A block diagram of a clock system shows how MSP430 controllers work with usually three clock sources (MCLK, SMCLK, and ACLK). As the image shows, MCLK is used as a clock source for the central processing unit. SMCLK is usually a high-frequency clock, and it is used for peripheral modules like timers and serial communication modules. ACLK is usually a 32KHz crystal clock and is used for peripheral modules that require a low-frequency clock like real team clocks. In the clock system block diagram showing, active mode means that MCLK, SMCLK, and ACLK have influenced the flash and RAM.
