SLAU367P October 2012 – April 2020 MSP430FR5041 , MSP430FR5043 , MSP430FR50431 , 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 , MSP430FR5969-SP , MSP430FR59691 , MSP430FR5970 , MSP430FR5972 , MSP430FR59721 , MSP430FR5986 , MSP430FR5987 , MSP430FR5988 , MSP430FR5989 , MSP430FR5989-EP , MSP430FR59891 , MSP430FR5992 , MSP430FR5994 , MSP430FR59941 , MSP430FR6005 , MSP430FR6007 , MSP430FR6035 , MSP430FR6037 , MSP430FR60371 , MSP430FR6041 , MSP430FR6043 , MSP430FR60431 , MSP430FR6045 , MSP430FR6047 , MSP430FR60471 , MSP430FR6820 , MSP430FR6822 , MSP430FR68221 , MSP430FR6870 , MSP430FR6872 , MSP430FR68721 , MSP430FR6877 , MSP430FR6879 , MSP430FR68791 , MSP430FR6887 , MSP430FR6888 , MSP430FR6889 , MSP430FR68891 , MSP430FR6920 , MSP430FR6922 , MSP430FR69221 , MSP430FR6927 , MSP430FR69271 , MSP430FR6928 , MSP430FR6970 , MSP430FR6972 , MSP430FR69721 , MSP430FR6977 , MSP430FR6979 , MSP430FR69791 , MSP430FR6987 , MSP430FR6988 , MSP430FR6989 , MSP430FR69891
There are three basic reference system requests that are used by the reference system. Each module can use these requests to obtain the proper response from the reference system. The three basic requests are REFGENREQ, REFBGREQ, and REFMODEREQ. No interaction is required by the user code. The modules automatically select the proper request.
A reference request signal, REFGENREQ, is available as an input into the REFGEN subsystem. This signal represents a logical OR of individual requests coming from the various modules in the system that require a voltage reference to be available on the variable reference line. When a module requires a voltage reference, it asserts its corresponding REFGENREQ signal. When the REFGENREQ is asserted, the REFGEN subsystem is enabled. After the specified settling time, the variable reference line voltage is stable and ready for use. The REFVSEL settings determine which voltage is generated on the variable reference line.
After the specified settling time of the REFGEN subsystem, the REF_A module sets the REFGENRDY signal. This signal can be used by each module to wait, for example, before a conversion is started after a REFGENREQ was set. The generation of the reference voltage can be triggered by a timer or by software to make sure that the reference voltage is ready when a module requires it.
In addition to the REFGENREQ, a second reference request signal, REFBGREQ, is available. The REFBGREQ signal represents a logical OR of requests coming from the various modules that require the bandgap reference line. When the REFBGREQ is asserted, the bandgap and its bias circuitry and local buffer are enabled, if not already enabled by a prior request.
After the specified settling time of the REFBGREQ subsystem, the REF_A module sets the REFBGRDY signal. This signal can be used by each module to delay operation while the bandgap reference voltage is settling. The generation of the buffered bandgap voltage can be triggered by a timer or by software to make sure that the reference voltage is ready when a module requires it.
The REFMODEREQ request signal configures the bandgap and its bias circuitry to operate in either sampled or static mode of operation. The REFMODEREQ signal represents a logical AND of individual requests coming from the various analog modules. A REFMODEREQ occurs only if a REFGENREQ or REFBGQ is also asserted by a module, otherwise it is a don't care. When REFMODEREQ = 1, the bandgap operates in sampled mode. When a module asserts its corresponding REFMODEREQ signal, it is requesting that the bandgap operate in sampled mode. Because REMODEREQ is a logical AND of all individual requests, any modules that request static mode cause the bandgap to operate in static mode. The BGMODE bit can be read for use as an indicator of static or sampled mode of operation.