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Replicape rev B

Revision as of 18:13, 6 September 2016 by Elias (talk | contribs) (Connectors)





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

Fritzing example


Connector overview


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.

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


The TMC2100 stepper drivers are designed to be very quiet. However, if the coil resistance on the steppers are too high, the current limit on the stepper drivers are never reached, and this makes the steppers give off a very high pitch sound. If you are experiencing high pitch noise, you might want to experiment with the "stealth mode" which will silence all steppers. This is micro stepping level 7 and 8. Stealth mode might make the steppers somewhat less powerful, but should work for most printers. To calculate if the current limit is reached or not, you can calculate the maximum coil resistance for a given input voltage. If the input voltage is 12V and you want to run your steppers on 1A current limit, the maximum coil resistance can be 12 ohm.






Thermocouple is not supported out of the box, but instead requires some extra care in order to work. Most importantly is to use a voltage divider on the signal so it is converted to a value that the analog input on the BeagleBone can handle: 1.8V. Secondly, the input needs to be sent in on AIN0..AIN3, which are pins P9_37...P9_40. Then, the analog input used needs to be enabled by a device tree overlay, ideally by editing the current DTO. That can be found here: https://github.com/eliasbakken/bb.org-overlays. Finally, the software needs to be hacked to make use of the new analog input and conversion.

Inductive sensors

Inductive sensors are typically mounted on the end stop marked Z2. If you have an NPN (sinking) sensor, you can mount it directly on there. Typically
Brown: 12V (pin 4)
Blue: GND (Pin 2)
Black: Sig (Pin 1, square)
If you have a PNP (sourcing) type, you need to add a pull-down resistor externally between the signal and ground on the sensor. The value is not important, as long as it can comfortably pull a 4.7K resistor low. 1K should be fine.

DS18B20 temperature sensors


Switches as end stops

All the end stops have 4.7K (47K on Rev B3) pull-up resistors on the signal lines. Therefore, the best way to connect switches is between the signal and ground pins on the connectors. If the switches have can be connected as normally closed (NC), that is preferable since it will act as a pressed in switch if a cable has been destroyed or removed.

The signals on the end stops as as follows:
pin 1, square, signal
pin 2, round, GND
pin 3, round, VCC (5V)


Replicape comes with Molex screw terminals for the heaters, hot bed and power input. Most stepper motors comes with the 4 pin Molex 2.54 mm (0.1") female connector attached. Fans and end stops sometimes comes with the right connector, but not always, it depends on the manufacturer. 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:
Here is a couple of good mating products:

3 pin
For the 3 pin end stop and Dallas 1W inputs:
Mating alternatives:

4 pin
Mating alternatives:



Note that if you do not power the Replicape, the BBB will not be able to properly communicate with it, and you will get an error such as

kamikaze redeem[675]: Error accessing 0x70: Check your I2C address

Hardware source files


Routing and noise

Component placement

Board extensions

Hardware details

Pins on the BeagleBone used by replicape
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.

High power MOSFETs
Maximum voltage: 30V
Maximum current: 40A

Low Power MOSFETs
4X AO7400
Maximum voltage: 30 V
Maximum current: 1.7 A

Thermistor inputs
The thermistor inputs have a first order low pass filter with a cut off frequency of 3.4 Hz. Since only slow moving signals are measured, this cuts out all capacitive influence from the high power heater cables that typically run in parallel with the thermistor cables.

Power management
Replicape has two step down voltage regulators or 5V and 12V, both built using Richtec RT8268GFP.




On the Debian/kamikaze image:

 sudo -s
 wget https://bitbucket.org/intelligentagent/replicape/raw/bf08295bbb5e98ce6bff60097fe9b78d96002654/eeprom/Replicape_00B3.eeprom
 cat Replicape_00B3.eeprom > /sys/bus/i2c/drivers/at24/2-0054/at24-1/nvmem


Rev B3

The first batch revision is Rev B3

- Power save mode is not implemented correctly. Therefore there will be some 3 seconds of noise from the steppers until u-boot can configure the SPI registers correctly. 
- Some boards have shipped without the EEPROM flashed. To fix that: http://wiki.thing-printer.com/index.php?title=Replicape_rev_B#Debian

Rev B2
