SLAA834B May 2018 – August 2021 MSP430FR2000 , MSP430FR2032 , MSP430FR2033 , MSP430FR2100 , MSP430FR2110 , MSP430FR2111 , MSP430FR2153 , MSP430FR2155 , MSP430FR2310 , MSP430FR2311 , MSP430FR2353 , MSP430FR2355 , MSP430FR2422 , MSP430FR2433 , MSP430FR2475 , MSP430FR2476 , MSP430FR2512 , MSP430FR2522 , MSP430FR2532 , MSP430FR2533 , MSP430FR2632 , MSP430FR2633 , MSP430FR2672 , MSP430FR2673 , MSP430FR2675 , MSP430FR2676 , MSP430FR4131 , MSP430FR4132 , MSP430FR4133 , MSP430FR5720 , MSP430FR5721 , MSP430FR5722 , MSP430FR5723 , MSP430FR5724 , MSP430FR5725 , MSP430FR5726 , MSP430FR5727 , MSP430FR5728 , MSP430FR5729 , MSP430FR5730 , MSP430FR5731 , MSP430FR5732 , MSP430FR5733 , MSP430FR5734 , MSP430FR5735 , MSP430FR5736 , MSP430FR5737 , MSP430FR5738 , MSP430FR5739 , MSP430FR5847 , MSP430FR58471 , MSP430FR5848 , MSP430FR5849 , MSP430FR5857 , MSP430FR5858 , MSP430FR5859 , MSP430FR5867 , MSP430FR58671 , MSP430FR5868 , MSP430FR5869 , MSP430FR5870 , MSP430FR5872 , MSP430FR58721 , MSP430FR5887 , MSP430FR5888 , MSP430FR5889 , MSP430FR58891 , MSP430FR5922 , MSP430FR59221 , MSP430FR5947 , MSP430FR59471 , MSP430FR5948 , MSP430FR5949 , MSP430FR5957 , MSP430FR5958 , MSP430FR5959 , MSP430FR5962 , MSP430FR5964 , MSP430FR5967 , MSP430FR5968 , MSP430FR5969 , MSP430FR59691 , MSP430FR5970 , MSP430FR5972 , MSP430FR59721 , MSP430FR5986 , MSP430FR5987 , MSP430FR5988 , MSP430FR5989 , MSP430FR59891 , MSP430FR5992 , MSP430FR5994 , MSP430FR59941
Unlike the FR59xx Clock System (CS), which uses an internal digitally controlled oscillator (DCO) to provide precalibrated frequencies (the fixed frequency points), the FR4xx clock system (CS) uses an internal digitally controlled oscillator (DCO) plus a frequency-locked loop (FLL) to provide frequencies.
A significant difference in the FR4xx DCO with FLL is that it can be configured only to the factory-provided frequencies and does not provide the in-between frequency steps that are available on the FR59xx DCO.
If an in-between frequency is necessary when using an FR4xx MCU, there is a workaround to implement it using the DCOFTRIMEN and DCOFTRIM bits in user code.
The FR4xx devices provide all of the same clock source options and system clocks as the FR59xx family. However the clock distribution system is simplified. For example, SMCLK is always derived from MCLK. There is a SMCLK divider (DIVS) between MCLK and SMCLK. However, the MCLK divider DIVM also affects SMCLK.
FR59xx clock distribution is more flexible than FR4xx. For example, the VLO can be the ACLK source in FR59xx, but in the FR4xx family this feature is available on only FR235x, FR215x, FR267x, and FR247x devices. It is not available on the rest of the FR4xx devices.
For more detailed information, see the Clock System chapter in the MSP430FR4xx and MSP430FR2xx family user's guide. Each FR4xx device can have differences in its clock distribution system (see the clock distribution table in the device-specific data sheet for details).