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Attention! The product has been discontinued. Check other products in category. |
Description: SparkFun Big EasyDriver A4988 - 35V 1.4A stepper motor controller with voltage regulator
The Big Easy Drive A4988 is a system for controlling stepper motors with a supply voltage up to 35 V and a maximum current per coil of 1.4 A. It can operate in five modes: full step, 1/2, 1/4, 1/8 and 1/16 step. There is a voltage regulator on the board so that there is no need to provide separate power supply to the logical part. The module can control both bipolar and unipolar motors, see the manual for details.
Stepper motor controller specification:
- Motor supply voltage: 8 V - 35 V
- Current: max. 1.4 A per coil (if the value is close to maximum, the manufacturer recommends usinga heat sink)
- The logical part works with voltages of 3.3 V and 5 V
- Built-in voltage regulator for the logical part
- Simple control interface
- 5 different modes of operation: full step, 1/2, 1/4, 1/8 and 1/16 step
- Possibility to adjust the current drawn by the motor by means of a potentiometer
- The module is compatible with 4, 6 and 8-wirestepper motors
- Control is by 5 V or 3.3 V signals (after soldering the jumper)
- Module dimensions: 38 x 31 mm
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Arduino compatible product A detailed description of the connection can be found inthe user guide. |
Control
One pulse given on the STEP pin causes one motor step in the direction selected by giving the appropriate logical state on the DIR pin. If the motor is to rotate in only one direction, the DIR pin can be permanently connected to VCC or GND.
| Pin | Description |
|---|---|
| ENABLE | The low state switches on the system outputs. The output in low state by default, pulled to ground by 20 kΩ resistor - the circuit is on. |
| MS1, MS2, MS3 | Choice of resolution. The default value is 1/16 step, determined by 20 k pull-up resistors. |
| RST | Low status resets the system. The output is high by default, pulled up through a 20 kΩ resistor. |
| SLEEP | Low status switches the system to standby mode. The output is high by default, pulled up by a 20 kΩ resistor. |
| VCC | Power supply to the logical part or voltage output after the voltage regulator. |
| GND | The weight of the system. |
| STEP | The pulse given on the STEP pin causes one motor step according to the set resolution. |
| DIR | Selection of direction of rotation. |
| M+, GND | Stepper motor power supply. |
| A, B | Outputs for stepper motor connection. |
| 3/5V APWR | The module has a built-in voltage regulator for the logical part. The user can select the supply voltage using this jumper |
Resolution
Step size is selected using MS1,MS2, MS3inputs. The possible settings are shown in the table below. The default device is set to step 1/16.
| MS1 | MS2 | MS3 | Resolution |
|---|---|---|---|
| low | low | low | Full step |
| high | low | low | 1/2 step |
| low | high | low | 1/4 step |
| high | high | low | 1/8th step |
| high | high | high | 1/16 step |
Current limitation
The A4988 module allows for active current limitation with a potentiometer. One of the ways to introduce the limitation is to set the controller to full step mode and to measure the current flowing through one coil without giving 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). SeeA4988documentation for more details.
Useful links |
