L9779WD-SPI datasheet(68/141 Pages) STMICROELECTRONICS

68 / 141 page

Functional description

L9779WD-SPI

68/141

DocID027721 Rev 2

Stepper is controlled by the logic AND between PWM input pin and PWM SPI bit. Thus to

control it by PWM input, SPI PWM bit must be set first, and to do it by SPI PWM bit, PWM

input pin must be set first.

If the bit EN=1, the writing of bit PWM from 0 to 1 leads to the next step of the turn on

sequence. The writing of bit PWM to 0 left unchanged the MOS of the bridge that is ON. The

step is done only if the PWM bit goes from 0 to 1.

The order of the turn-on sequence is defined by the bit DIR.

The initial stepper position, after power-on, is the one with OUTA_HS, OUTB_LS ON in

Hbridge1 and with OUTD_HS, OUTC_LS ON in Hbridge2.

If configured as H-bridges the internal logic prohibits that the low-side and the high-side

switch of the same half-bridge will be switched on simultaneously.

In the below diagram the stepper motor operation is available.

Table 29. Configuration of the stepper motor

PWM

DIR

H-bridge 1 Power on

H-bridge 2 Power on

None

OUTA_HS, OUTB_LS

OUTD_HS, OUTC_LS

OUTA_HS, OUTB_LS

OUTC_HS, OUTD_LS

OUTB_HS, OUTA_LS

OUTC_HS, OUTD_LS

OUTB_HS, OUTA_LS

OUTD_HS, OUTC_LS

OUTA_HS, OUTB_LS

OUTD_HS, OUTC_LS

OUTB_HS, OUTA_LS

OUTD_HS, OUTC_LS

OUTB_HS, OUTA_LS

OUTC_HS, OUTD_LS

OUTA_HS, OUTB_LS

OUTC_HS, OUTD_LS

L9779WD-SPI Datasheet(PDF) 68 Page - STMicroelectronics