Datasheet

TMC4671 Datasheet • IC Version V1.3 | Document Revision V2.00 • 2020-Apr-17

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Note

The open-loop encoder is useful for initial ADC setup, encoder setup, Hall signal

validation, and for validation of the number of pole pairs of a motor. The open-

loop encoder turns a motor open with programmable velocity in unit [RPM] with

programmable acceleration in unit [RPM/s].

With the open-loop encoder, the user can turn a motor without any position sensor and without any

current measurement as a ﬁrst step of doing the system setup. With the turning motor, the user can

adjust the ADC scales and oﬀsets and set up positions sensors (Hall, incremental encoder, . . . ) according

to resolution, orientation, and direction of rotation.

4.6.2 Incremental ABN Encoder

The incremental encoders give two phase shifted incremental pulse signals A and B. Some incremental

encoders have an additional null position signal N or zero pulse signal Z. An incremental encoder (called

ABN encoder or ABZ encoder) has an individual number of incremental pulses per revolution. The number

of incremental pulses deﬁne the number of positions per revolution (PPR). The PPR might mean pulses

per revolution or periods per revolution. Instead of positions per revolution, some incremental encoder

vendors call these CPR counts per revolution.

The PPR parameter is the most important parameter of the incremental encoder interface. With that, it

forms a modulo (PPR) counter, counting from 0 to (PPR-1). Depending on the direction, it counts up or

down. The modulo PPR counter is mapped into the register bank as a dual ported register. The user can

overwrite it with an initial position. The ABN encoder interface provides both the electrical position and

the multi-turn position, which are accessible through dual-ported read-write registers.

Note

The PPR parameter must be set exactly according to the used encoder.

Figure 20: Number of Pole Pairs NPP vs. mechanical angle phi_m and electrical angle phi_e

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