SPMD150STP

Function description and application information

Doc ID 17160 Rev 1

17/23

Figure 17.

Half step mode

4.5.2

Normal drive mode (full-step two-phase-on)

A Low level on the HALF/FULL input selects the full step mode.

If the low level is applied when the state ma1chine is at an ODD numbered state, the normal

drive mode is selected.

Figure 18 shows the motor current waveform state diagram for the state machine of the

phase sequencer generator.

The normal drive mode can be selected easily, by holding the HALF/FULL input low and

applying a RESET. AT start -up or after a RESET the state machine is in state1.

After the HALF/FULL input is kept low, state changes following the sequence 1,3,5,7,… if

CW/CCW is high (Clockwise movement) or 1,7,5,3,… if CW/CCW is low (Counterclockwise

movement).

Figure 18.

Normal drive mode

4.5.3

Wave drive mode (full-step one-phase-on)

A low level on the pin HALF/FULL input selects the full step mode.

If the low level is applied when the state machine is at an EVEN numbered state, the wave

drive mode is selected.

Figure 19 shows the motor current waveform and the state diagram for the state machine of

the phase sequence generator.

To enter the wave drive mode the state machine must be in an EVEN numbered state.

An example of selecting the wave drive mode is the following:

to apply a RESET first;

keeping the HALF/FULL input high, to apply one pulse to the CLOCK input;

then, to apply the logic level Low to the HALF/FULL input.

This sequence first forces the state machine to sate 1.