Decapede Electronics is a low-cost 10 stepper motor controller and driver. A 20 amp 24VDC driver is also added for one large out (drive motor, multiple extruders, total board power shunt, etc). It is fully open source, and compatible with Arduino mega 2560 boards, all revisions. We will also release an open source firmware based on Sprinter.
The addition of a second board, reprap expansion, is provided. This board also allows for 8 controlled outputs like fans, and 8 thermistor reads. It also provides 4 free input/output pins that will be used for SDramps
The boards were developed, funded, and supported by Armanicreations and Industries3D.
The discussion forum on Reprap.org http://forums.reprap.org/read.php?2,193415 has provided much insight and suggestions for this board.
Documentation/Updates are also on Armanicreations.com http://armanicreations.com/main/decapede-electronics/
Microcontroller Board: Arduino Mega Rev3 http://arduino.cc/en/Main/arduinoBoardMega2560
- Power for arduino is provided by the Decapede onboard 5V regulator.
- Inputs: Up to 24VDC (two inputs and two grounds)
- Power regulator: A power regulator is provided to output up to 5VDC up to 1A for arduino and thermistors
- Max power consumption 1200W (30V/40A)
- Suggested max continuous power: 480W (24V/20A)
- Fuse: Onboard self resetting fuse Up to 30V/40A http://www.digikey.com/product-detail/en/MF-R900/MF-R900-ND/259981
- Decapede Main FET: 60V/55A http://www.digikey.com/product-detail/en/STP55NF06L/497-6742-5-ND/1039551
- Pinning: See datasheet for stepstick and endstop pinning. The large FET is tied to the LED pin 13.
Stepper Driver Boards:
- Use standard stepstick format boards:
- Recommended for 1A continuous current: http://www.pololu.com/catalog/product/1182
- Recommended for 1.5A continuous current
- Recommended for 2A continuous current: DRV8811 Stepstick will be released soon
- Recommended for 3A continuous current: In3D Stepstick will be released in the future: TBD
- Inputs: Uses power input from decapede, and 5VDC from the regulator.
- Thermistors: 7 thermistor header pins are provided with 5V, and voltage measurement is connect through arduino. These are for NTC thermistors.
- Switched outputs: 8 FET outputs are provided capable of 40V/24A peak. http://www.digikey.com/product-detail/en/PSMN023-40YLCX/568-10157-2-ND/3598046. These are quite overpowered, so that any one FET can be used to power a heated bed or extruder. However, even though they are capable of very high peak currents to ensure part safety, they are intended to be use for a combined 20A continuous power usage. In combination with decapede, total continuous draw should be only 40A total. A typical reprap extruder uses 3.3A and a typical fan uses 1A. Four of the output fets are marked as being capable of PWM.
- SDRamps: Currently this board is under modification to allow sdramps.
- Pinning: Thermistors 1,2,3,4,5,6,7 are on arduino pins 69,68,67,66,65,64,63 respectively. The FETS 1,2,3,4 without PWM capability are on pins 29,33,38,39 respectively. FETS_PWM 1,2,3,4 has PWM capability and are on pins 38,39,6,19 respectively. Additional digital I/O pins 22,23,27,28 are available. These are being modified to match the SDramps format.
Recommended Power Supply: These days, we highly recommend a linear regulated power supply. For example, 240W 24V/10A amp units are costing 50 USD (2013). Do not use an ATX power supply, as these create noise, break easily, create feedback, can crash the arduino during power surges, and are overpriced. Avoid the use of a "Switching" power supply because these create ripple current that makes motors noisy and can cause low torque and missed steps.
Additional specification will be coming as we finalize production. Attached in a zip file of the pre-production pin assignments for the Arduino Mega pins to Decapede and ReprapExpansion http://reprap.org/mediawiki/images/7/77/Decapede_Pin_Mapping_Rev_09.zip
Decapede Feature I - 10 Stepper output
Each board was designed to work with any stepstick standard format board, like Stepstick, G3D, or DRV8825. This way any broken boards can be replaced.
The output of stepper boards for controlling bipolar stepper motors is A B B A (motor windings for phase A and B on the row of 4 output female header pins). On other controllers (not Decapede), it may be A A B B - please make sure your motors are wound accordingly.
The jumpers for Decapede are designed so that no jumpers = maximum microstepping. This way, if you loose jumpers or dont have 30 extra ones, you have the most popular settings already hard coded. For most applications, microstepping should be used to increase accuracy of positioning, smoothness of motion, and reduce motor noise. However, it does increase computational demands on the Arduino Mega.
We are currently designing a new Stepstick like board based on DRV8811 for Decapede specifically, to aim towards 2.5A peak current output. We are also designing a separate 3A continuous duty board (10A peak). This is mainly aimed at extreme torque for filament extrusion or CNC motors.
Decapede Feature II - 1 Massive FET output
A very large FET is provided for driving up to 20 amp and 24VDC. Technically, the load can be 60V/50A, but the wires only support this.
Decapede Feature III - Expansion pins
Two expansion pins are provided capable of feeding 24VDC / 8A into the next board. 5VDC is also fed into 3 pins. Ground connectors are provided. There are 4 free PWM pins, 8 analog pins, and 8 more digital pins on the expansion header.
Decapede Feature IV - Stepper Linkers
For users wanting to use one driver for 2 or more motors, or wanting to try linking of multiple stepstick outputs for larger power, a linker is being developed. This will have two 4-pin female headers and yield a single 4-pin male header output. In this instant the maximum theoretical output would be 4A. This way across all 10 boards, CNC users could drive 4A over 5 axis.
Reprap Expansion Feature I - 4 PWM FETS
Four 1A outputs are provided capable of PWM because they are connected to PWM outputs on arduino
Reprap Expansion Feature II - 4 More FETS
Four more 1A FET outputs are provided but do not provide PWM.
Reprap Expansion Feature III - 7 Thermistor Header
7 Thermistor headers are provided. They use a standard voltage divider using 5VDC from the regulator, and measure the loss of voltage as the temperature increases and resistance in the NTC thermistor drops. These headers consume all remaining analog inputs.
Reprap Expansion Feature IV - 4 pin digital IO pins
The remaining pins from arduino were routed for access. Such pins could drive external circuits like the Powerswitch tail to control 120VAC. These are currently being redesigns to map to the same pins as SDramps on RAMPS.
Examples of use
Decapede comes out of a need to have a single, simple, and easy to program system for stepper motors. Ideal applications include:
Driving complex robotics with central drive motor Assembling remote control system Low cost factory automation Multi axis CNC machines General robotics prototyping Testing 3D printers/RepRaps with multiple extruders or mixing nozzles We are open to your design suggestions for future revisions. Many have suggested the use of an ARM processor and PIC drivers to allow for greater processing power and we are looking into it.
Where/when to get it
We will either purchase and sell 100 sets of boards or launch a crowd source campaign in the June/July 2013. After that the boards would be sold directly on Industries3d.com or resold through distributors like Robotshop.com (TBD).
Designer and Principal: Michael Armani (Reprap user Simba)
Designer: David Jones
Electronics Designer 1: Am Miram
Electronics Designer 2: Miroslav Mrdjan
Naming the device: Reprap user Ugen