This pin determines the direction of motor rotation. Direction and size of step is controlled by DIR and MSx pin settings.ĭIR: Logic Input. Any transition on this pin from LOW to HIGH will trigger the motor to step forward one step. The IC will return the FETs to the home microstepping position found in the diagrams on page 14 of the datasheet upon receiving a HIGH signal on this pin. When switching this pin to HIGH to wake up the IC, allow 1 ms of delay before sending a STEP signal. When set to LOW, the A4988 enters sleep mode, and disables functionality of the FETs, internal current regulator and charge pump. This must be set HIGH to enable functionality of the motor driver. The translator is set to the Home state as well. When set LOW, all STEP commands are ignored and all FET functionality is turned off. See truth table below for HIGH/LOW functionality. Microstep Select 3 has a pull-up resistance of 20 kOhms. Microstep Select 2 has a pull-up resistance of 20 kOhms. Microstep Select 1 has a pull-up resistance of 20 kOhms. If set to LOW, all FETs will be enabled, allowing motor control. If set to HIGH, the FETs will be disabled, and the IC will not drive the motor. Enables the FET functionality within the motor driver.
Other half of connection point for bi-polar stepper motor coil B.ĮNABLE: Logic Input. Half of connection point for bi-polar stepper motor coil B.Ĭoil B-: DMOS Full Bridge 2 Output A. Other half of connection point for bi-polar stepper motor coil A.Ĭoil B+: DMOS Full Bridge 2 Output B. Half of connection point for bi-polar stepper motor coil A.Ĭoil A-: DMOS Full Bridge 1 Output A. Board Top PinsĬoil A+: DMOS Full Bridge 1 Output B. Several pins of the A4988 IC are broken out on the Big Easy Driver, allowing direct connection to a bi-polar stepper motor, as well as a microcontroller. Functionality between the two sets does not change. You can use whichever pin connections work best for your project. The secondary connection points are closest to the edge of the board, and are spaced to fit 2-pin screw terminals.
The first, which are the pins closest to the center of the board, are spaced out to fit standard 0.1" headers. Each pin present on the board has two connection points. The Big Easy Driver is designed around the Allegro A4988 motor driver.
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