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Difference between revisions of "Replicape rev B"

(Testing Replicape)
(Hardware details)
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''' Pins on the BeagleBone used by replicape'''<br>
 
''' Pins on the BeagleBone used by replicape'''<br>
 
Below is a diagram of the pins that have been used on the BeagleBone.  
 
Below is a diagram of the pins that have been used on the BeagleBone.  
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<a href="http://www.thing-printer.com/wp-content/uploads/2015/12/Replicape_pinout_rev_B3.png"><img src="http://www.thing-printer.com/wp-content/uploads/2015/12/Replicape_pinout_rev_B3.png" alt="Replicape_pinout_rev_B3" width="500" height="450" class="alignnone size-full wp-image-1139" /></a>
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<img src="http://www.thing-printer.com/wp-content/uploads/2013/11/Replicape_pinout_rev_A4-e1384823678555.png" width="100%"/>
 
<img src="http://www.thing-printer.com/wp-content/uploads/2013/11/Replicape_pinout_rev_A4-e1384823678555.png" width="100%"/>
  

Revision as of 13:05, 9 December 2015

Replicape is a high end 3D-printer electronics package in the form of a Cape that can be placed on a BeagleBone Black. This page is about the Major revision B. It has five high power and low noise stepper motors with cool running MosFets and it has been designed to fit in small spaces without active cooling and without the need for physical access to the board once installed. That means no potentiometers to trim or switches to flip.

This page is about the hardware. It explains how to install the board and wire everything up. If you are looking for software that will run, have a look at the Kamikaze CNC image. There are other options as well, but that is the standard that will work for most people.

Availability

There has been a Kickstarter for Replicape Rev B. Since the Kickstarter is done, Replicape Rev B can be ordered from the thing-printer web shop.

Mounting the Replicape on the BeagleBone.

As the name suggests, Replicape is a cape. Capes are one of the defining things about BeagleBone black/white/green, where the main development board acts as a base unit, and then accepts different add-on hardware through the two 48 pin headers, which in turn define some of the pin behaviors during Linux kernel startup. This is similar to "shields" on Arduino and "HAT"s on Raspberry Pi. Mounting the Replicape on BeagleBone should be pretty straight forward, just make sure the notch in the cape goes around the Ethernet connector so it makes a.. cape!

How to wire up the board

Fritzig example

The Fritzing board below shows the most basic setup for connecting the board.

Connector overview


Steppers

Bipolar and hybrid stepper motors are supported with these stepper motor drivers (SMD). Some smaller stepper motors are known to produce a high pitch noise and get very warm even with a low current setting. They will appear to work, but they may very well burn do to the large heat being produced.

With the board oriented as in the above image, the wires for the steppers are:
Rev B2: 1, 2, 3, 4 = OB1, OA1, OA2, OB2<- Not so standard
Rev B3: 1, 2, 3, 4 = OA2, OA1, OB1, OB2<- Pretty standard

Heaters

The heater output on the Replicape have rugged connectors, with the heat bed having double connectors for redundancy (in case one wire comes loose) and for handling the power load. These are brand Molex connectors that have both screw terminals for easy fitting and slot in connectors for easy disassembly. All the heaters are controlled with PWM. The power MOSFETs controlling the output are AON6758 that are rated at 30V, 32A. For a 12V PSU, this means that the maximum power that can be used on the heated bed is 32 A x 12 V = 384 W. Please remember that there is a 20 A fuse preventing such a large power use on the heated bed. The 20 A fuse is installed to keep the traces on the PCB from over heating.

Thermistors

The thermistor inputs on Replicape have been designed for 100 K NTC thermistors. These are the typical type used for desktop 3D-printers. 10K thermistors can also be used, however the voltage divider setup makes the 100 K thermistors more ideal since the area of most change will be around 100 degrees. TODO: add charts for 10 K and 100 K thermistors showing their ideal temperature for most significant bit change.

DS18B20 temperature sensors

The connector marked Dallas W1 can be used for connecting temperature sensors of the type DS18B20. These are relatively low temperature sensors that can handle up to 125 degrees Celsius and are typically used for monitoring the cold end of the extruder which should never reach more than around 60 degrees when printing with PLA. The great thing about using a cold end monitor is that the temperature measurements can be used to regulate the fan on the extruder. That way, the noise level can be lowered further than when using the thermistor as a trigger for enabling the extruder fan.


Connectors

The white 2, 3 and 4 pin connectors on Replicape used for thermistors, end stops and steppers are the MTA-100 series from TE connectivity:

2 pin
For the 2 pin thermistor inputs and fan outputs:
https://www.digikey.com/product-detail/en/640455-2/A19450-ND/258997
Here is a couple of good mating products:
http://www.digikey.com/product-detail/en/1375820-2/A99613-ND/1864915
http://www.digikey.com/product-search/en?keywords=952-2227-ND

3 pin
For the 3 pin end stop and Dallas 1W inputs:
https://www.digikey.com/product-detail/en/640455-3/A19451-ND/258998
Mating alternatives:
https://www.digikey.com/product-detail/en/1375820-3/A99614-ND/1864916
http://www.digikey.com/product-search/en?keywords=952-2228-ND

4 pin
For the 4 pin stepper motor connectors, and the inductive sensor input:
https://www.digikey.com/product-detail/en/640455-4/A19452-ND/258999
Mating alternatives:
http://www.digikey.com/product-detail/en/1375820-4/A99615-ND/634994
http://www.digikey.com/product-search/en?keywords=%09952-2229-ND

Power

Replicape is powered through a single 12 to 24 V power supply. This powers the BeagleBone as well, through a 5V step down converter. It also supplies 12V for fans and the inductive sensor. If the USB device connector is used, no power is drawn through the connector.

Hardware source files

If you want to extend, build or modify Replicape, for the repository:
https://bitbucket.org/intelligentagent/replicape

Routing and noise
The Rev B PCB is a four layer PCB. The top layer is mostly vertical traces and the bottom layer is mostly horizontal. The uppermost inner layer is a ground layer with no signal traces. The lower inner layer is the voltage plane layer. There are in total 4 voltage planes: 12..24V, 12V, 5V and 1.8V. In addition, there is a 3.3 V trace routed.

Component placement
All components are placed on the top layer to reduce cost of manufacturing. There are two fiducials on the top side to aid in pick and place placement of components.

Board extensions
Revision B does not have a dedicated extension header like the one that was introduced in rev A4A.There should still be possible to add an extension board on top of the current version that can add up to three more extruders. This has not been designed yet.

Hardware details

Pins on the BeagleBone used by replicape
Below is a diagram of the pins that have been used on the BeagleBone. <a href="Replicape_pinout_rev_B3.png">Replicape_pinout_rev_B3</a>

Stepper Motor Controllers
There are 5 Stepper Motor Controllers (SMDs) of the type TMC2100 (datasheet) on Replicape. With the right stepper motors, they reduce the noise level a lot compared to other, similar type SMDs. The peak current is rated at 2.5 A, with an RMS current pr phase of 1.2 A. TMC2100 has over temperature protection. If skipped steps occur, it might be due to over heating. To distribute heat better, there are exposed areas directly under the stepper drivers where heat sinks can be mounted. In that case, you may want to consider adding active cooling to lead the air flow away from the gap between the BeagleBone and the cape.

TODO for Rev B

High power MOSFETs
TODO for Rev B

Low Power MOSFETs
TODO for Rev B

Thermistor inputs
TODO for Rev B

Power management
TODO for Rev B

Update EEPROM

The EEPROM on the Replicape should be updated when it arrives. If not, here are the instructions on how to update it.

Debian

On the Debian/kamikaze image:

 sudo apt-get install nodejs-legacy
 wget https://bitbucket.org/intelligentagent/replicape/raw/f623a0304134b3effcc427a82de1ebbf7cee82bb/eeprom/replicape_0A4A.json
 wget https://bitbucket.org/intelligentagent/replicape/raw/a2b195880014c7c27aabd7c0a8d140c5564007ad/eeprom/eeprom.js
 wget https://bitbucket.org/intelligentagent/replicape/raw/a2b195880014c7c27aabd7c0a8d140c5564007ad/eeprom/bone.js
 node ./eeprom.js -w replicape_0A4A.json
 cat Replicape.eeprom > /sys/bus/i2c/drivers/at24/2-0054/nvmem/at24-1/nvmem

Please note the address on the I2C bus, it might be 55, 56 or 57 depending on your settings.

Testing Replicape

A script is available for testing the board. This is inteded for manufacturers, but could be useful for end-users as well. To install the test script do the following. Install the test script package:

 cd /usr/src/
 git clone https://bitbucket.org/intelligentagent/replicape
 cp /usr/src/replicape/test/test-replicape.service /lib/systemd/system
 systemctl enable test-replicape

Use the "testing" config file for Redeem:

 cd /etc/redeem
 ln -s testing.cfg printer.cfg

Finally, since the boards to test/flash do not have eeprom when plugged in, it must be enabled through the command line.

 nano /boot/uEnv.txt

Make sure the line about cape manager is set:

 cape_enable=bone_capemgr.enable_partno=BB-BONE-REPLICAP:00B3

Errata

Rev B3

The first batch revision is Rev B3

Rev B2

Replicape Revision B2 has a hardware error. This board was only manufactured for beta testing and has "developer edition" clearly shown on the board. The error is that 470K resistors were mounted instead of 4.7K for the thermistor voltage divider. The resistors were manually changed to 5.1K resistors. The thermistor voltage divider resistance value needs to be updated in software to reflect this. Add the following section to the file /etc/redeem/local.cfg

[Heaters]
resistance_e = 5100.0
resistance_h = 5100.0
resistance_hbp = 5100.0