SLAZ453Z May   2014  – August 2021 MSP430FR5849

 

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6.45 USCI50

USCI Module

Category

Functional

Function

Data may not be transmitted correctly from the eUSCI when operating in SPI 4-pin master mode with UCSTEM = 0

Description

When the eUSCI is used in SPI 4-pin master mode with UCSTEM = 0 (STE pin used as an input to prevent conflicts with other SPI masters), data that is moved into UCxTXBUF while the UCxSTE input is in the inactive state may not be transmitted correctly.  If the eUSCI is used with UCSTEM = 1 (STE pin used to output an enable signal), data is transmitted correctly.

Workaround

When using the STE pin in conflict prevention mode (UCSTEM = 0), only move data into UCxTXBUF when UCxSTE is in the active state.  If an active transfer is aborted by UCxSTE transitioning to the master-inactive state, the data must be rewritten into UCxTXBUF to be transferred when UCxSTE transitions back to the master-active state.