RepRap Minitronics v1.1 User manual

Minitronics v1.1 Quick Start Guide Version 1.2
Copyright 2014, Reprapworld.com - 1
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Thank you for purchasing the Minitronics v1.1! This small guide will answer the
basic questions on how to connect the board to your 3D printer. For more
information visit the ReprapWorld.com product page. ReprapWorld.com may
provide updates to the firmware, documentation and specifications. Please refer
to the Minitronics page for the latest information.
Safety warnings
Do not exceed the recommended voltage for the board. With the SRC12v
Jumper in place, the maximum voltage rating for power input is 12V. Without
the jumper, the board can be powered with a maximum voltage of 24V.Also do
not turn the stepper drivers while connected to the electronics, as this may result
in high voltages running through the board.
The USB-connector is protected from shorts by a resettable fuse. The 12V inputs
are protected by a NON-resettable fuse. Shorting the 12V line or reversing
power polarization may cause the SMD fuses to burn out, requiring replacement
of the fuses.
Do not unplug stepper motors from the board while powered. This may cause the
stepper drivers to be damaged permanently. Before powering the stepper drivers
adjust the current, see the section 'adjusting current'.
Use the fan included in the kit to cool the board. This increases the max current
settings of the stepper drivers.
Features
The Minitronics board is designed to be an easy to use, compact and smart
solution to fit 90% of the 3D-printers. Unlike the Megatronics, which targets at the
advanced ranged of usages, the Minitronics is plug and plug, which will fit the
needs of the average user better.
Atmega1281
PowerfulAtmega1281 processor with 128 KB memory, running at 16Mhz
Thermistors
Two have pull up resistors to hook up thermistors directly. One has not, so you
can hook up an external thermo couple pcb. Optionally you can solder the third
4k7 resistor to have three thermistors.

Minitronics v1.1 Quick Start Guide Version 1.2
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External SD card support
You can now hook up an external SD card pcb, so you can print directly from SD.
Four MOSFETs
The board has 3 regular MOSFETs and one MOSFET for the heated bed (10A)
Up to 5 stepper drivers with 1/32 step
The Minitronics has four on board stepper drivers.Afifth can be connected
externally, using our External stepper driver board.
Preparing the board
The board is supplied with a Marlin firmware. Because of the continued
development and your specific needs, changes are you want to upload another
firmware.
You need a special Arduino version as provided by us on our site. Look in the
Software downloads section under service / support. Once downloaded and
installed, you can select the Minitronics board from the menu and upload a
sketch. Check the datasheet for port mappings and detailed technical
information.
We also supply a pre-configured Marlin version, you only need to adjust the
specific settings for your printer.
Adjusting current
Before powering the stepper drivers, be sure to adjust the current. The current
determines the torque the stepper motors will deliver, but also causes heat. You
can adjust the current by turning the trimpot for each stepper driver. DO NOT
turn the trimpot with power enabled, this may cause permanent damage to the
board.

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Locate the trimpot next to the stepper driver. Turn it fully to the left (1) to disable
the current. Then turn it about 45 degrees to the right (2). This should allow the
axes to move. If you are loosing steps during the print, you may need to increase
the current a bit. If the stepper is shutting down while printing, the chip is
probably getting to hot. Decrease the current of add extra cooling to the board.
Testing the board
To test the functionality of the board, a test firmware is available from the product
page. This firmware will help you test the board. Disconnect everything except
the USB cable to your computer. Upload the the test firmware to the board
withArduino, the blue debug LED should blink every second. By using the serial
monitor inArduino the board will provide an output like:
T1 1023 T2 1023
These values represent the resistance measured from t1 and t2. When you
connect a thermistor to the pins, the corresponding value in the serial monitor
should change to about 890.
By connecting the 12V line, the MOSFETs should have power and their LEDs will
blink in order. This verifies the MOSFETs and 12V power are OK.
Also the stepper motors should turn when connected, with the 12V lines and
stepper wiring in place. They will turn a short time and switch direction.
These three tests will verify the basic functionality of the board.
Quick Start
This paragraph will show you how to connect the board. This is just a basic
example, your requirements may differ. There is a lot of community support
available in the RepRap forums http://forums.reprap.org. By placing your
questions there other users may benefit of the information too.

Minitronics v1.1 Quick Start Guide Version 1.2
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First connect your computer with a standard USB cable. The power LED should
light up and the blue debug LED should blink once. The rxd and txd LEDs near
the USB connector may blink fast for a short period.
Connect the stepper drivers to the designated connectors. You can connect up to
5 stepper motors, 1 for each axis, except for the Z-axis, which allows two stepper
motors to be connected.Also an external stepper driver is supported, check the
datasheet for more details. You can use the following order of colors, but if you
reverse the connector, the stepper motor will just reverse.

Minitronics v1.1 Quick Start Guide Version 1.2
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The power supply should be connected to the board using the provided wire.
Mind the polarization, the yellow wires should be +.
Connect the heated bed to HB, this terminal allows larger currents, up to 10A.
The first extruder heater should be connected to E1.Asecond extruder can be
connected to E2.
You can easily connect end stops to the board. There is support for 3 end stops.
For opto end stops you will need the S(ignal), - and + pins. For mechanical end
stops the S(ignal) and –pins are sufficient.
The thermistors for reading heated bed and extruder temperature can be
connected to the thermistor pins. Polarization is not an issue here.

Minitronics v1.1 Quick Start Guide Version 1.2
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Advanced usage
Connecting a second extruder or third extruder
You can hook up another extruder using the external driver output. You won't be
able to use the heated bed however, because the board has only support for 2
thermistors.
Connecting a servo motor
Some use cases for a servo include heated bed leveling or a nozzle sweep.
Minitronics supports a servo using PWM on pin 6, also the Z axis end stop signal
pin. So effectively this will replace the Z axis end stop, but that isn't required for
bed leveling. If you do need a Z axis end stop, you can use a free digital I/O from
the AUX header. Connect the servo like this:
Yellow is signal, which needs to be on pin S of the header. Brown is -, while
orange is +5V. Note you can also draw 5v from a different power supply, in case
you have more peripherals drawing power.
In marlin's configuration.h uncomment the line #NUM_SERVOS 1.After
uploading send M280 P0 S180 and then M280 P0 S0 to test the servo.
Warranty
We provide a three months limited warranty on the board. You should verify the
proper function of the board when it arrives, you may use the test firmware as
described in the paragraph 'Testing the board'. When you have determined that
the board is not functioning properly, please provide a detailed description of the
problem including pictures (if applicable) to [e-mail]. Make sure
to include your order number.