- The motor supply voltage: 8 V to 35 V
- Czterowarstwowa PCB
- Current: max. 1,2, And reel (if applying cooling to 2 A)
- The simple control interface
- Work in 5 different modes: full step, 1/2, 1/4, 1/8 and 1/16 step
- The ability to adjust the current consumed by the motor with a potentiometer
- Overheat protection system
- The module is fully compatible with the predecessor: A4983
The system allows you to control a stepper motor using a device that allows you to generate the logical state, for example, Aa rduino, STM32Discovoery, the Raspberry Pi people of any microcontroller. The Pololu module is characterized by a very simple operation. In order to rotate the motor one step, you must specify the STEP output high (logical unit), another sequence of zeros and ones moves the motor one step, etc. the Choice of direction is accomplished by depositing as the output DIR (e.g., low - momentum clockwise, a low - versa). The driver also has the choice of resolution of operation of the engine.
In contrast to the green of the A4988 module, black tiles made according to the technology czterowarstwowej. which allows for more efficient heat transfer. Thanks to this module can provide 1.2 A per coil without mounting the radiator.
To control a stepper motor bipolarnym it is necessary to connect the system in accordance with the following figure. In the case of engine control unipolarnym must read the instructions. If the nominal voltage of the motor is lower than required power supply driver (8 V), manually with the potentiometer to set the current limit.
The illustration shows the minimum connection driver. Pin the factory default RESET is not connected to start the system, it is necessary for him to indicate the status of high. This can be done by combining it with an adjacent terminal SLEEP.
To power the logic part of the module, you need the voltage ranges from 3 V to 5.5 V, which should be brought into contact VDD. The motor supply voltage is in the range from 8 V to 35 V is supplied to pin UMOT. The system can control the engines with a rated voltage lower than the required 8 V. In this case, it is necessary to limit the maximum current through the potentiometer, so as not to exceed the maximum power of the engine.
The connection and disconnection of the engine while the driver is turned on can damage the system.
The step size is selected via the inputs MS1, MS2, MS3. Possible settings are shown in the table below. Inputs MS1, MS2 and MS3 have internal resistor pull-down (100kOm).
One pulse on the specified pin STEP causing one step of the motor in the direction selected by making the appropriate logic state on the output DIR. Conclusions STEP and DIR are not internally pulled up. If the motor should only rotate in one direction the DIR pin can be permanently connected to VCC or GND.
The system has three inputs for monitoring power consumption: SLP EN RESET and their description is in documentation. Please note that the pin RESET to nothing pulled. If not used, you can connect it to the surrounding contact SLEEP.
The A4988 module allows the active current limit with the potentiometer. One of the ways the introduction of restrictions to set the driver to full step and measuring the current passing through one coil without signal at the input STEP. The measured current is 70% of the established limit (both coils are always on and limited to 70% of full step). Another way is to measure the voltage at pin REF (marked with a circle on the PCB), as well as the calculation of the current limit (measuring resistors have a value of 0.05 Ohms). More detail in the documentation for the A4988 chip.
The tile was designed so that it can conduct heat when the current consumption is about 1.2 A per coil. If the current is much higher, use an external heatsink to which the installation, you can use glue, thermo-conductive.