Description

A4988 module – stepper motor controller

A4988 Stepstick motor driver module is a stepper motor driver with up to 2A current per coil and a wide supply voltage range from 8V to 35V.

Circuit commonly used in CNC machines and 3D printers (RepRap) and others.

Product features

• A4988 Stepstick motor driver module heatsink included
• Controller ideal for 3D printers (RepRap)
• Examples of use in CNC Shield for 3D Printers
• Stepper motor controller based on the A4988 chip.
• Wide range of supply voltage 8 – 35 V
• Large operating current of up to 2 A per coil.
• Maximum resolution: 1/16 step.
• Note! Connecting and disconnecting the motor while the controller is on can damage the system.

Technical data

• Module equipped with A4988 chip
• Motor supply voltage: 8-35 V
• Max current: 2A with heat sink
• Operation in 5 different modes: full step, 1/2, 1/4, 1/8 and 1/16 step
• Possibility to adjust the current drawn by the motor with a potentiometer – ceramic screwdriver available here.
• Protection against overheating of the system

Included

• Stepper motor controller module A4988
• Radiator

Important information

• Wiki to A4988
• Reprap – driver description
• Controller data sheet

Detailed description of the controller

1. Control
• The module is characterized by very simple operation.
• In order to rotate the motor by a step, a high state (logical one) must be given to the STEP lead, the next sequence of zero and one will move the motor by the next step, etc.
• Selection of the direction is carried out by applying the appropriate state to the DIR pin (e.g., low state – clockwise rotation, low state – counterclockwise).
• The controller also has a selectable motor resolution.
2. Power supply
• To power the logic part of the module, a voltage in the range of 3V to 5.5V is required, which should be applied to the VDD pin.
• The motor supply voltage from 8V to 35V is applied to the VMOT pin. The system can be used to control motors with a nominal voltage lower than the required 8V. To do this, limit the maximum current draw using a potentiometer so as not to exceed the allowable motor current. E.g. for a motor with a resistance of 5Ω per coil and current consumption of 1A, the nominal supply voltage is 5V. When supplying 12V, limit the current so that it does not exceed 1A.
3. Other inputs
• One pulse applied to the STEP pin causes one motor step in the direction selected by applying the corresponding logic state to the DIR pin.
• STEP and DIR outputs are not internally pulled up.
• If the motor is to spin in one direction only, the DIR pin can be permanently connected to VCC or GND.
• The circuit has three more inputs to control power consumption: RESET SLP and EN their description can be found in the documentation.
• Note that the RESET pin is not connected to anything. When not in use it can be plugged into the adjacent SLEEP pin.
4. Current limitation
• A4988 module allows active current limitation using a potentiometer.
• One way to implement the limitation is to set the controller to full step mode and measure the current flowing through one coil without applying a signal to the STEP input.
• Measured current is 70% of the set limit (both coils are always on and limited to 70% in full step mode).
• Another way is to measure the voltage at the REF lead (marked with a circle on the PCB) and calculate the current limit (the measurement resistors have a value of 0.05Ω).
• For more details, see the A4988 chip documentation.
5. Heat dissipation:
• The board is designed to be able to dissipate heat at a current consumption of about 1A per coil.
• If the current will be much higher, it is necessary to use an external heat sink for the installation of which you can use thermally conductive glue – heat sink in our offer

Controller diagram