GAUPS 0.2 Instructions

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What's Different

Top of GAUPS 0.2 board

GAUPS 0.2 (beta) is almost identical to the 1.0 (final) version. The differences are:

  • The board is green, not blue;
  • Instead of jumpers (JP1) for selecting between dual-Y and fourth axis, it has a DIP array (SW2);
  • The RESET switch is labelled SW3;
  • The positive and negative supply terminals are swapped (connector P5);
  • There are a few more traces on the back of the board (the 1.0 ground plane is slightly better);
  • Some pads are a different size;
  • It does not have a cool A/S/L logo on the back.

Other than that, the boards are identical. The schematic is exactly the same.

Open Source

GAUPS is derived from Bart Dring's open-source Arduino-compatible Stepper Motor Driver Shield rev 3. Thank you, Bart!

GAUPS is open-source hardware, released under the Creative Commons Attribution-ShareAlike 3.0 License. However, as GAUPS 0.2 was a beta version, we ask you to use the GAUPS 1.0 files instead.


Bottom of GAUPS 0.2 board

Please follow the illustrated GAUPS 1.0 Instructions. The boards are nearly identical, so the instructions apply as well, with these changes:

  • Step 2: solder both DIP arrays (SW1 and SW2);
  • Step 3: the switch is SW3;
  • Step 7: skip this step;
  • Step 10: set SW2 (see #Switch Settings below).

Driver Orientation

Driver pin EN (ENABLE) is marked with an arrow on the silkscreen (please note that this changed in the 1.0 version). The motor outputs (1A, 1B, 2A, 2B) face the respective screw terminals. The electrolytic capacitor is near the VMOT pin, and the yellow ceramic capacitor is near the VDD pin.

Note that two drivers (X and Y) are oriented one way, the other two (Z and A) the other way.


The motor screw terminals are connected to the driver output nearest to them, in the same order.

The motor power supply input is P5, the two bottom screw terminals in the block of ten at the left of the board. Negative is next to the X axis motor terminals, positive at the bottom edge of the board. Please note that this has changed in version 1.0 of the board.

Do not make or break any connections while the board or the Arduino are powered. There is a high risk of destroying the drivers and/or the Arduino.

Switch Settings

Switches are OFF to the left (the side of the switch with the numbers), ON to the right (the side labelled "ON").

For Dual-Y operation, the A driver takes the same control signals (STEP and DIR) as the Y driver. For 4-axis operation (or spindle relay in the A axis slot), STEP and DIR for the A driver come from Arduino pins D12 and D13.

SW2 Dual-Y 4 axes
1 OFF       ON
2 OFF       ON
3       ON OFF
4       ON OFF

SW1 controls the microstepping for the four drivers. The silkscreen is labelled to show which switches apply to which driver.

SW1 switch A4988 and DRV8825 A4988 DRV8825 DRV8834
X axis Y axis Z axis A axis Pin name 1 × 2 × 4 × 8 × 16 × 16 × 32 × Pin name 2 × 4 × 16 × 32 ×
10 4 7 1 MS1 OFF            ON OFF       ON       ON OFF       ON M0       ON OFF       ON OFF
11 5 8 2 MS2 OFF OFF       ON       ON       ON OFF       ON M1 OFF OFF            ON       ON
12 6 9 3 MS3 OFF OFF OFF OFF       ON       ON       ON (CFG) not used

For instance, to set a DRV8825 driver on the Z axis to 8 × microstepping, set switches 7 on, 8 on, 9 off. In the Dual Y configuration, it's simplest to use the same type of driver and motor for both the Y axes (Y and A), and use the same microstepping configuration for both (switches 1–3 same as switches 4–6).

Note that it is not possible to select all microstepping combinations for the DRV8834 low-voltage stepper motor driver (1 × and 8 × would require pin M0 to be held low).