Texas Instruments MSP430x4xx - Manual (Page 480)

Scan IF Operation
24-20 Scan IF
24.2.3 Scan IF Processing State Machine
The PSM is a programmable state machine used to determine rotation and
direction with its state table stored within MSP430 memory (flash, ROM, or
RAM). The processing state machine measures rotation and controls interrupt
generation based on the inputs from the timing state machine and the analog
front-end. The PSM vector SIFPSMV must to be initialized to point to the PSM
state table. Multiple state tables are possible by reconfiguring the SIFPSMV
to different tables as needed. The PSM block diagram is shown in
Figure 24−11.