L6474PD datasheet(20/51 Pages) STMICROELECTRONICS

20 / 51 page

Functional description

L6474

20/51

Doc ID 022529 Rev 2

6.5

Absolute position counter

An internal 22 bit register (ABS_POS) takes memory of motor motion according to the

selected step mode; the stored value unit is equal to the selected step mode (full, half,

quarter, etc.). The position range is from -221 to +221-1 (µ) steps (see Section 9.1.1).

6.6

Step sequence control

The motor movement is defined by the step clock signal applied to the STCK pin. At each

step clock rising edge, the motor is moved by one microstep in the direction selected by DIR

input (high for forward direction and low for reverse direction) and absolute position is

consequently updated.

6.7

Enable and disable commands

The power stage of the device can be enabled and disabled through the respective SPI

commands.

The enable command turns on the power outputs and starts the current control algorithm.

The phase currents are controlled according to present EL_POS value. If a fault condition

requires the power stage to be disabled, the command is ignored.

The disable command immediately forces the power outputs in a high impedance condition.

L6474PD 数据表(PDF) 20 Page - STMicroelectronics