A4988 Stepstick Ramps Stepper Motor Driver Reprap, CNC 3D Printers
A4988 is a driver for stepper motors with a current of up to 2A. The system is commonly used in CNC machines and 3D printers.
The A4988 Stepstick stepper motor driver module includes a heat sink
Ideal driver for 3D printers (RepRap)
Example application in CNC Shield for 3D Printers CNC Shield V3.00 - Shied 3D Printers for A4988
Stepper motor driver based on the A4988 system.
Wide range of supply voltage 8 - 35V
High operating current up to 2 A per coil.
Maximum resolution: 1/16 step.
Attention! Connecting and disconnecting the engine with the controller turned on may damage the system.
The module is equipped with the A4988 chip
Motor supply voltage: 8-35V
Max current: 2A with a heat sink
Work in 5 different modes: full step, 1/2, 1/4, 1/8 and 1/16 step
Possibility to regulate the current consumed by the motor with a potentiometer
Protection against overheating of the system
A module with a stepper motor driver A4988
Detailed description of the driver
The module is very easy to use.
In order to rotate the motor one step, you should enter a high level on the STEP pin (logical one), another sequence of zeros and ones will move the motor one step, etc.
The choice of the direction is done by giving the appropriate level to the DIR output (e.g. low level - turns clockwise, low level - on the contrary).
The controller also has the option to select the resolution of the engine operation.
To power the logic part of the module, a voltage in the range of 3 V to 5.5 V is required, which should be connected to the VDD pin.
The motor supply voltage in the range from 8 V to 35 V is supplied to the VMOT pin.
The system can control motors with a nominal voltage lower than the required 8 V. To this end, the maximum current consumption should be limited by the potentiometer, so as not to exceed the permissible motor power.
3. Other inputs
One pulse given to the STEP pin causes one step of the motor in the direction selected by giving the appropriate logic level to the DIR pin.
The STEP and DIR pins are not internally pulled up.
If the motor is to turn in one direction only, the DIR pin can be permanently connected to VCC or GND.
The system has three more inputs for controlling power consumption: RESET SLP and EN - their description can be found in the documentation.
Note that the RESET pin is not tucked up for anything. If it is not used, it can be connected to the adjacent SLEEP pin.
4. Current limitation
The A4988 module allows active current limitation with a potentiometer.
One of the ways of introducing a 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.
The 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 on the REF pin (marked with a circle on the PCB) and calculate the current limit (measuring resistors have a value of 0.05Ω).
More details in the documentation for the A4988 chip.
5. Heat dissipation:
The board has been designed so that it can dissipate heat with a current consumption of about 1A per coil.
If the current is much higher, an external heat sink should be used, which can be mounted with thermally conductive glue.