Description
At the heart of the module is the DRV8825 stepper motor driver with heatsink. The DRV8825 driver is ideal for size stepper motors Nema 17. It is suitable for 4, 6 or 8 wire 2 phase stepper motor if connected correctly. The module has pins that are almost identical to those of the A4988 stepper motor driver, so it can be used as a replacement for the A4988 in many applications.
DRV8825 heatsink stepper motor driver and its features
- Simple interface to control steps and direction
- Six different step resolutions: full, half step, 1/4 step, 1/8 step, 1/16 step and 1/32 step
- Can be directly connected to 3.3 V and 5 V systems
- Works from 8.2 to 45V
- It allows up to about 1.5A per phase without a heatsink or active airflow (rated up to 2.2A per coil with sufficient additional cooling).
- Automatic protection against excessive temperature, low voltage and excessive current
- Exposed “ground” pad under the driver IC on the bottom of the PCB
- The module size and pinout match the A4988 stepper motor driver in most respects
- Adjustable current control allows you to set the maximum output current with a potentiometer, allowing you to use voltages above the rated voltage of the stepper motor to achieve higher stepper speeds
- Intelligent "chopping" control that automatically selects the correct current current decay (fast decay or slow decay)
- Built-in regulator (external logic supply not required)
- For easy installation of DRV8825 driver we can use Expansion board for DRV8825
Dimensions DRV8825
Terminals and connections
The DRV8825 stepper motor driver has a total of 16 pins that connect it to the outside world. The links are as follows:
Warning: The DRV8825 stepper motor driver uses low ESR ceramic capacitors, which makes it susceptible to high LC voltage spikes, especially when using power cables longer than a few centimeters. Under the right conditions, these voltage spikes can exceed the DRV8825's 45V maximum and permanently damage the board, even if the motor supply voltage is only 12V. One way to protect the driver from such voltage spikes is to use a large (100 µF recommended) electrolytic capacitor between the terminals motor (VMOT) and ground somewhere near the board.
Warning: Connecting or disconnecting the stepper motor while the driver is powered may permanently damage the driver.
The DRV8825 driver has three inputs to select the microstep resolution, M0, M1 and M2. By setting the appropriate logic levels on these pins, the motor can be controlled with one of eight resolutions.
M0 | M1 | M2 | Micro step resolution |
Low | Low | Low | A full step |
High | Low | Low | Half a step |
Low | High | Low | 1/4 step |
High | High | Low | 1/8 step |
Low | Low | High | 1/16 step |
High | Low | High | 1/32 step |
Low | High | High | 1/32 step |
High | High | High | 1/32 step |
These three microstepping pins are pulled to a logic LOW level by internal “pull-down” resistors, so that if left disconnected, the motor will run at full step.
If you need help controlling the DRV8825 with an Arduino or other microcontroller, please feel free to contact us you contact.
Setting the correct current on the DRV8825 driver
There is a small potentiometer on the DRV8825 driver that you can use to set the maximum current. The maximum current must be set to the value of the rated current of the motor or lower.
The maximum current can be set by measuring the voltage (Vref) at the “ref” terminal (potentiometer).
- Look up the rated current for your stepper motor in the documentation for your stepper motor. In our example, we use a NEMA 17 with a rated current of 250 mA.
- Set the driver to full step mode leaving the three micro step pins M0, M1, M2 unconnected.
- Leave the motor in a fixed position by not applying STEP pulses per step.
- Measure the voltage (Vref) on the metal part of the potentiometer itself.
- Adjust the voltage Vref according to the formula: Vref = Maximum current x 0.5
For example, if your motor is rated at 250mA, set the reference voltage to 0.125V.
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