![]() The A4988 stepper motor driver can be connected to a microcontroller like Arduino to control the speed, number of revolutions and direction of rotation of a stepper motor. MS1Ĭonnecting A4988 Stepper Motor Driver to Arduino. Microstep settings in A4988 can be changed by setting the appropriate logic levels for MS1, MS2 and MS3 pins to give one of five step resolutions as indicated below. Motor drivers that supports microstepping mode like A4988 allow higher resolutions for stepper motors by allowing intermediate step locations through energizing the motor phases with intermediate current levels.įor example, when in ½ step mode, the stepper motor will make 400 microsteps per revolution and in ¼ step mode it will make 800 microsteps per revolution. Stepper motors normally make 200 steps per revolution in full-step mode which gives a step size of1.8°. Therefore to get more than 1A per coil, a heat sink is required. This is because the A4988 driver IC has a maximum current rating of 2A per coil but if more than 1A per coil is supplied, a lot of heat is dissipated which can eventually damage the IC. The A4988 driver comes with a heatsink and it is good practice to install it before using the driver. MS1, MS2, MS3 – Microstep selection pins used to set the microstep resolution depending on the different combinations of inputs as detailed in the next section.ENABLE – This pin active low and is enabled by default so the driver is always enabled unless you pull it high.This pin is floating and if you are not using this pin, you can connect it to the SLEEP pin to make it high and enable the driver. ![]() ![]() RESET – is also an active low input and when activated, it ignores all inputs sent to the “STEP” pin until deactivated.Pulling this pin LOW puts the driver into sleep mode, minimizing power consumption especially when the motor is not in use to save power. The faster the pulse, the faster the motor will spin. STEP – for controlling the microsteps of the motor by sending HIGH pulses to this pin.The motor spins clockwise or counter-clockwise depending on whether this pin is pulled LOW or HIGH. DIR – used to determine the direction of rotation of a stepper motor.One coil of the stepper motor goes through 1A and 1B, and the other through 2A and 2B. 1A, 1B, 2A, 2B are output pins connected to the bipolar stepper motor coils.GND is connected to ground pin of the microcontroller and VDD is connected to 5V. GND and VDD on the lower right side are power supply for the internal circuit of the A4988 driver.GND and VMOT on the top right side are the connections for the motor power supply taking on 8V – 35V depending on the motor you are using.The A4988 stepper motor driver board has a total of 16 pins as shown below: Microstep resolution of full, 1/2, 1/4, 1/8 and 1/16.Continuous current per phase of 1A and Maximum current per phase of 2A.This motor driver is based on the A4988 DMOS Microstepping Driver IC from Allegro with Translator and Overcurrent Protection. I also have tutorials on other stepper motor drivers that you can check out using the links below Ī4988 Stepper motor driver hardware overview The A4988 stepper motor driver is used for controlling small and medium-sized bipolar stepper motors like NEMA 17 stepper motor used in 3D printers and CNC machines
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