Texas Instruments MSP430x4xx Family User Manual page 846

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Table of Contents

Scan IF Operation

Figure 30−20. Quadrature Decoding State Diagram

Table 30−8.Quadrature Decoding PSM Table

Correct State Transitions

To transfer the state encoding into counts it is necessary to decide what

fraction of the rotation should be counted and on what state transitions. In this

example only full rotations will be counted on the transition from state 00 to 01

or 10 using a 180° disk with the sensors 90° apart. All the possible state

transitions can be put into a table and this table can be translated into the

corresponding state table entries for the processing state machine as shown

in Table 30−8.

Turns right, +1

Turns left, −1

Erroneous State Transitions

State Table Entry