DRV8825 Stepper Driver

Driver DRV8825 stepper motor

The DRV8825 is a driver for stepper motors IT, improved from the A4988. With 1/32 microstepping up giving the movement of stepper motors bipolar great finesse, it can deliver up to a theoretical maximum of 2.2A per phase with forced air ventilation or no ventilation or sinks 1.5A by both these power increases.

Another important improvement is that the DRV8825 is mounted on a printed circuit layers 4 therefore heat dissipation is improved in the driver

The printed circuit DRV8825 can be mounted directly on the sockets 1.4 Ramps shields or plates or other supporting these drivers. The module has an interface and pinout that are almost identical to those of drivers A4988 stepper motor, which can be used as a driver DRV8825 higher performance microstepping or as replacement plate plates that and is mounted on A4988.

Main features of DRV8825

• Six resolutions micro different steps: full step to 1/32 micro steps.
• It has an automatic voltage regulator, which effectively results in quieter operation and less vibration
• Adjustable current control that lets you adjust the maximum current output with a potentiometer.
• Supply voltage 45 V maximum
• 4-layer printed circuit
• Protection against short-circuit and overtemperature.

Note: The DRV8825 is mounted upside down the A4988

737px-Stepper_drivers_mixed_a4988_drv8825_RAMPS_1a

You can see a comparison of DRV8825 with the A4988 (Article AndrewBCN)

DRV8825 as replacing the printer or similar BCN3D + RepRap

Whether you want to replace a faulty driver or do an update of all drivers, we have to follow these simple steps if we do not want to modify the firmware of our 3D printer.

We just have to remove the old A4988 drivers (white on BCN3D +), draw two jumpers on the electronic board Ramps and place the new driver (purple) in the correct orientation.

As a picture is worth a thousand words, then we can see the jumpers have been removed. The withdrawal of these jumpers makes new drivers are compatible with previous, avoiding having to make any additional changes.

drv8825 en la ramps

Here we describe as regular drivers correctly to provide the necessary power to the engines and everything runs smooth and without overheating.

The drivers are controlled by a small knob having at one end. If we rotate clockwise increase the power counterclockwise disminuimos.Por default, factory are poorly regulated and therefore be good practice to devote time to the correct calibration. If the change as they come, we run the risk of delivering more power to the engines and we can get to burn.

In the picture you can see that the potentiometer has a small chamfer on the head (a flat face). We have found that orienting the flat side up, adjust the driver got quite well without a multimeter or tester.

ajustedrv8825 drv8825 setting 2

For the more “experienced / theoretical” users the possibility to calibrate the drivers with a tester. To do this, please read this article before the RepRapWiki. We can say that we must be careful not to cause any short circuit, there is a risk of damaging some electronic component of the machine.

Advanced – Change firmware in BCN3D +

If you please make the most of the DRV8825 with all its microstepping (quieter and fine in movement printer), we have to modify the firmware of the BCN3D + (the guide also serves for 3D RepRap printers, but obviously the values ​​are different ).

They must be all jumpers inserted in the socket where new drivers are!

To configure the step / mm in the firmware have three options:

In this example all the drivers installed on the 1.4 Ramps are DRV8825

1.On screen: If we go to Menu> Control> Motion> Xsteps / mm, Ysteps / mm, Zsteps / mm, Esteps / mm

We must adjust the values ​​for each axis have changed the driver to twice the current value. Next, for which values ​​are not erased when turn off the machine, select the Store memory option in Menu> Control. The values ​​can be found in section 2.

2.Arduino IDE: We need to open the firmware with the Arduino and go to the tab 353 h locate line.

#define DEFAULT_AXIS_STEPS_PER_UNIT {80.19,80.43,2560,458.3}

These values ​​define the steps needed to travel a distance unit. We just have to modify multiplying by 2. So would this:

#define DEFAULT_AXIS_STEPS_PER_UNIT {160.38,160.86,5120,916.6}

3.USB: We need a program to open a serial communication with the printer via USB.

Once the connection is established we send the following g-codes that allow us to change the values ​​we seek.

M501 // read the values ​​stored in the EEPROM

M92 Z5120 X160.38 Y160.86 E916.6 // We modify the values ​​of Step / mm

M500 // We save the new values ​​in the EEPROM

M501 // We return to check the memory values ​​and verify the change