L6228Q datasheet(18/32 Pages) STMICROELECTRONICS

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Circuit description

L6228Q

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Doc ID 14321 Rev 4

4.7

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

A LOW level on the HALF/FULL input selects the full step mode. When the low level is

applied when the state machine is at an ODD numbered state the normal drive mode is

selected. Figure 19 shows the motor current waveform state diagram for the state machine

of the phase sequencer generator. The normal drive mode can easily be selected by holding

the HALF/FULL input low and applying a RESET. At start -up or after a RESET the state

machine is in state 1. While 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).

4.8

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

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

applied when the state machine is at an EVEN numbered state the wave drive mode is

selected. Figure 20 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. The most direct method to select the Wave Drive

Mode is to first apply a RESET, then while keeping the HALF/FULL input high apply one

pulse to the clock input then take the HALF/FULL input low. This sequence first forces the

state machine to state 1. The clock pulse, with the HALF/FULL input high advances the

state machine from state 1 to either state 2 or 8 depending on the CW/CCW input. Starting

from this point, after each clock pulse (rising edge) will advance the state machine following

the sequence 2,4,6,8,… if CW/CCW is high (clockwise movement) or 8,6,4,2,… if CW/CCW

is low (counterclockwise movement).

Figure 18.

Half step mode

Figure 19.

Normal drive mode

D01IN1320

2345678

IOUTA

IOUTB

CLOCK

Start Up or Reset

D01IN1322

3571357

IOUTA

IOUTB

CLOCK

Start Up or Reset

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