GAUPS 1.0 Instructions

From Amber Spyglass Ltd
Jump to: navigation, search

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. KiCAD files will be available here soon.


It's easiest to assemble the board in the order of component height, leaving the tallest last. For the parts with long leads, trim them as soon as you've soldered them (do not trim the Arduino headers, obviously). The instructions assume the board is held with the driver labels ("X AXIS" etc) the right way up, as shown.

Step Part Image and Instructions Board Image
GAUPS 1.0 R1.jpg
GAUPS 1.0 Assembly 01 R1.jpg
Solder R1 (10 kΩ resistor). Color code: Ra.pngRb1.pngRc.pngRd0.pngRe.pngRd0.pngRe.pngRd2.pngRf.pngRb1.pngRg.png (1%) or Ra.pngRb1.pngRc.pngRd0.pngRe.pngRd3.pngRf.pngRbG.pngRg.png (5%).
GAUPS 1.0 SW1.jpg
GAUPS 1.0 Assembly 02 SW1.jpg
Solder SW1 (12-way DIP switch). Orient it numbers to the left, "ON" text in the upper-right corner. The 1, 2 and 3 labels will match the 1, 2 and 3 silkscreen labels for the A axis.
GAUPS 1.0 SW2.jpg
GAUPS 1.0 Assembly 03 SW2.jpg
Solder SW2 (push-button), taking care not to overheat it.
GAUPS 1.0 C1-C4.jpg
GAUPS 1.0 Assembly 04 C1-C4.jpg
Solder C1, C2, C3, C4 (47 µF 35 V capacitors), paying attention to the orientation. Install with the negative terminal (shorter lead, marked with a stripe on the body of the capacitor) toward the middle of the board.
GAUPS 1.0 C5-C8.jpg
GAUPS 1.0 Assembly 05 C5-C8.jpg
Solder C5, C6, C7, C8 (100 nF capacitors). These are not polarized, so orientation doesn't matter.
GAUPS 1.0 U1-U4.jpg
GAUPS 1.0 Assembly 06 U1-U4.jpg
Solder the eight 8-way female headers for the drivers.
GAUPS 1.0 JP1.jpg
GAUPS 1.0 Assembly 07 JP1.jpg
Solder JP1 (2×3-pin male header). The holes for it are very tight (sorry!). The best way is to push it in with a flat, rigid object.
GAUPS 1.0 J1-J4.jpg
GAUPS 1.0 Assembly 08 J1-J4.jpg
Solder the two 6-way and two 8-way Arduino stacking headers, taking care to not to deposit solder on the long pins (except where they meet the PCB, of course). Make sure the pins are straight and parallel before soldering them.
9 GAUPS 1.0 J1, J2, J5 apart.jpgGAUPS 1.0 J3, J4 apart.jpg
GAUPS 1.0 J1, J2, J5 joined.jpgGAUPS 1.0 J3, J4 joined.jpg
GAUPS 1.0 Assembly 09 P1-P5.jpg
Join one 2-way and two 4-way screw terminals, by sliding the little dovetails into the slots. Solder them as P5, P1 and P2, with the openings for the wires toward the outside of the board. Join the remaining two 4-way screw terminals. Solder them as P3 and P4.
GAUPS 1.0 Jumpers.jpg
GAUPS 1.0 Assembly 10 JP1 DY jumpers.jpg
Install two jumpers on JP1, either in the DY position (shown) or the A position (not shown). See jumper settings below. Please note the orientation of the jumpers: they're vertical. Check all the soldering, remove any loose bits of solder, insert into the Arduino Uno, and you're done!

Driver Orientation

Please pay attention to driver orientation! A driver inserted backwards will be destroyed instantly when the power is turned on.

Driver pin VMOT (motor supply voltage) is marked with an arrow on the silkscreen (please note that this is different from the beta 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. The digital inputs are toward the middle of the board.

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

Jumper Settings

For Dual-Y operation, the A driver takes the same control signals (STEP and DIR) as the Y driver, acting as a second Y driver instead of a fourth independent axis. Install two jumpers in the positions marked 'DY' on the board.

For 4-axis operation (or spindle relay in the A axis slot, instead of a driver), STEP and DIR for the A driver come from Arduino pins D12 and D13. Install two jumpers in the positions marked 'A' on the board.

Dual-Y    4 axes

Note that, in either case, the jumpers are vertical (parallel to the short edge of the board).

Switch Settings

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

Microstepping is controlled independently for each of the four drivers. Each driver has three switches associated with it. The silkscreen shows 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).

gShield/grblShield Compatibility

To make a GAUPS behave exactly like a gShield (or an older grblShield with the Z-axis hack), so that one can use the same settings for GRBL, set X and Y to 8 × microstepping, and Z to 2 ×:

1       ON
2       ON
4       ON
5       ON
7       ON
10       ON
11       ON
12 OFF


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

The motor power supply input is P5, the two bottom screw terminals in the block of ten on the left side of the board. Positive is next to the X axis motor terminals, negative at the bottom edge of the board. Please note that this is different from the beta version. The polarity is marked on the silkscreen on the back of the board (there was no room on the front).

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.

GAUPS 1.0 Example Configuration

This image (click on it to enlarge) shows an example configuration:

  • Four drivers and four motors
  • Dual-Y (two Y motors, each with its own driver)
  • 16 × microstepping on the X and Y axes
  • Half-stepping (2 ×) on the Z axis
  • Pololu A4988 green drivers (note that other driver modules may have the trimpot in a different location, so do not use it to decide the driver module orientation. Always check the pin labels).
Bottom of GAUPS 1.0 PCB, showing supply polarity

Also, when using GRBL 0.8 or 0.9 with the "invert mask" set to 0, Pololu A4988 green or black drivers, and the motors we carry in our store, wired as shown, for a move in the positive direction of each axis, the motors turn as follows (as viewed looking into the shaft):

Axis Motor Axis Positive Direction Motor Direction
X Right Counter-clockwise
Y Left (Y driver) Toward the back Counter-clockwise
Right (A driver) Clockwise
Z Up Clockwise

This is the standard direction of travel for a dual-motor dual-Y drive eShapeoko with any of the standard eShapeoko belt configurations (teeth down, belt going under the idler wheels and over the belt pulley). This is also valid for a Shapeoko with any of the belt mods that have the belt facing teeth down. For the original Shapeoko configuration (belt teeth up, going over the idler wheels and under the belt pulley) and any other teeth up configuration, reverse the direction of X and Y motors (by reversing the connections, black–green–blue–red instead of red–blue–green–black).

Note that not all motors from all manufacturers turn in the same direction when wired the same, although this seems to be the most common case. If your motor has different color wires, always determine the correct pairing before wiring the motors, to avoid damage to the drivers. Any configuration will work, as long as the wires in each pair are next to each other (pins 1 and 2 one pair, pins 3 and 4 another pair).

Also note that driver modules other than Pololu A4988 may turn the motors in the opposite direction, too, and the direction can also be changed in firmware.

Power Supply

The choice of voltage depends on the driver modules. The kit of parts, as supplied, has capacitors rated at 35 V, so that's the maximum voltage. However, the capacitors can be replaced.

With A4988 drivers, the maximum voltage is 35 V, but EMF induced in the motor during braking can raise the supply voltage, so we do not recommend using more than 30 V. The DRV8825 drivers are rated to 45 V, but, for the same reason, we do not recommend more than 40 V (provided that the capacitors on the GAUPS have been replaced with ones rated 50 V or more).

A4988 and DRV8825 both work from 12 V, but the most popular voltage for them is 24 V. 19 V is also popular, because it's the typical voltage of a laptop power supply, and many people have one of those lying around.

The DRV8834 driver operates from 2.5 V to 10.8 V, so it's ideal for low-voltage applications.

Part List

Part Count Description Manufacturer Part Number
PCB 1 GAUPS 1.0 PCB, dual-side 1.6 mm FR4, through-plated, ENIG, RoHS Amber Spyglass Ltd
R1 1 Resistor, 10 kΩ 0.125 W, metal film Multicomp MF12 10K
C1–C4 4 Aluminium electrolytic capacitor, 47 µF 35 V, long life (5000 hours @ 105°C),
radial, 2.5 mm lead spacing, ∅ 8 mm, 5 mm tall
Rubycon 35ML47MEFC8X5
C5–C8 4 Ceramic capacitor, 100 nF 50 V, X7R dielectric, 0.2" lead spacing Multicomp MCRR50104X7RK0050
SW1 1 Low-profile 12-way DIP switch, 0.1" pitch, 0.3" wide Multicomp * MCEI-12
SW2 1 Tactile switch, 6 mm Panasonic EVQPVG05K
JP1 1 6-way dual-row male 0.1" pitch header, straight AMP * 826925-3
Jumper 2 Jumper for 0.1" pitch header, blue Harwin * M7583-05
U1–U4 8 8-way single-row female 0.1" pitch header, straight Multicomp * 2212S-08SG-85
J1, J2 2 6-way single-row long pin (15 mm) female 0.1" pitch headers, straight Samtec * SSQ-106-04-F-S
J3, J4 2 8-way single-row long pin (15 mm) female 0.1" pitch headers, straight Samtec * SSQ-108-04-F-S
P1–P4 4 4-way side-entry PCB screw terminal, 5 mm pitch Camden Boss CTB5202/4
P5 1 2-way side-entry PCB screw terminal, 5 mm pitch Camden Boss CTB5202/2

For most components, numerous equivalent parts exist from various manufacturers. The given manufacturers and part numbers are just examples of compatible parts. However, except where marked with an asterisk, the supplied parts in our kit are exactly those listed here (those with an asterisk are generic equivalents). This is especially important for the long-life electrolytic capacitors of the correct form factor, and for the good quality screw terminals. Also important are the long (15 mm pins) Arduino headers; the typical Arduino headers with 10–12 mm pins are not tall enough for the solder joints on the back of the shield to clear the Arduino USB connector, and insulation is required.

We reserve the right to substitute parts without notice.


GAUPS 1.0 schematic.png