Replicape Kickstarter is now live!

Replicape front page pictureMost of the posts on this blog have revolved around Replicape, the 3D-printer controller board made for BeagleBone Black. However, there was never a real launch for Replicape through the Zeitgeist crowd funding platform Kickstarter, until now, that is. There is now a brand new major revision of Replicape, and it is currently being launched on Kickstatrer as we speak!

Check it out, and grab one if you like 3D-printers and BeagleBone : )

Replicape Kickstarter

Manga Screen Kickstarter is live!


It has certainly been longer than expected, but now the Kickstarter for Manga Screen has finally gone live!

The development of the Manga Screen was first documented here, and even the very inception can be seen in the rant I had back in the day about there not being any small HDMI compatible screens available. Since then, the screen has gotten a custom Capacitive touch panel that fits in the FF-18 socket of the LQ043Y1DX07 and is ready for some volume.

This screen is an important piece of the puzzle for Replicape as well. I’ve been working a lot (and I mean a lot!) on a new piece of software called Toggle which is an app that fits perfectly together with Redeem and Manga Screen to give the 3D-printer a nice on-board user interface with hardware OpenGL ES 2 accelleration through the PVR SGX engine on the BBB. So use Octoprint to control the 3D-printer through a web interface, Cura to control it via USB or Toggle to control it directly on the printer.

If you like the stuff you read on this blog or you need one of those screens for your BeagleBone Black projects (or similar dev boards), be sure to grab one from the first batch! I’m quite thorough with development, so I’m quite sure the product will live up to your standards! If not, you always have the option of improving it, since everything I do is open source adn with very liberal licenses.

The funding is already going well and the staff of Kickstarter ha even made it a pick, which is great!


Continue reading about BeagleBone Black

I’ve started writing down my latest findings about BeagleBone Black on the Thing printer website. Currently only three posts, but in my own humble opinion, worth a read : )

Replicape Front Page Picture

I’ve also started the pre-sale of Replicape! The Replicape is now at Revision A4A with an added expansion port for a little project I’ve called Reach, which is basically a second cape that slots on top of Replicape giving it three more extruders for those interested in experimenting with CMYK color blending or similar. There are also a few improvements to the layout for some more noise reduction.

Update: will be featured on! Yay!

Replicape Rev A4 ready for review

Replicape-1-of-6Replicape revision A4 is finally ready for review! The important changes include a brand new layout (Huge thank you to Stoneshop for sending me a brand new layout, that’s what open source hardware is all about), a few grips for reducing the noise and a few tweaks on the user interface. If anyone else besides David from CircuitCo wants to do layout revision, go right ahead! Comments are welcome.

A lot of people a have been asking about the board and when it will be ready and all I can say is: Soon! CircuitCo will be producing the board, testing it and handling RMAs and it will be sold through all your favorite electronics distributors (The same that sell BeagleBone black), so when it finally starts selling, it will definitely be available! I have not yet been able to get a definite date from CircuitCo, but they are reviewing as we speak, so I’m estimating sales will begin in a matter of weeks. The price is $179.

As for the software, there have been a lot of improvements in speed and bug fixing. Since this summer, there has been a software bug in the ADC driver that has caused a few of the measurements to be dropped giving unreliable temperature readings. A backport from the 3.12 kernel seems to have fixed this, so everything looks great. In fact We are now aiming at a Kickstarter in Q1 of 2014, in the meantime, here is a video showing an early prototype of Thing printer printing something : )

Tree frog on Thing from Elias Bakken on Vimeo.

Also, Koen has been doing a great job getting Slic3r running on Angstrom, so I’m working hard on moving everything to the 2013.06 dist of Angstrom so I can finally slice directly on the printer. Yay!

Most readers of this blog are very familiar with the features of the Replicape, but if not, have a look at the repository for an overview of the features. I also had a beer with Simen of the Bengler project yesterday, the guy that wrote the original code for GRBL, which is the the core of just about every desktop 3D-printer available. He gave me some great tips on improving the path planner in Replicape. In particular he mentioned having an n-step path segment prediction instead of the 18-step currently available on the Arduinos. Also, he pointed out that there would probably be a significant noise reduction in the steppers due to the much more fine pitch timing of the steps from the 200 MHz PRUs compared to the 3o kHz timers in the Arduions. He also liked the readability of code from writing Python : )

Sorry for not updating the blog lately, I’ve been busy with a paper, but now that that’s handled, I’m back baby! As a band-aid, here is a picture of the brand new Manga Screen (Rev A3) that arrived yesterday.

Manga Rev A3

DC-DC buck converter noise on Replicape

image (2)

The Replicape has two DC-DC buck step down regulators, one for supplying the 5V to the BeagleBone (Black), a MCP16321 and one 12V so you can use 12V fans or LEDs for keeping your stuff cool. (Pun intended)

When both the Replicape and the Manga Screen were finished and I was finally able to test them together, an issue arose. The screen would suddenly cut out during boot because the power to the USB was cut by the BBB. Only by lowering the brightness significantly and adding an extra electrolytic capacitor across the 5V input was I able to make them work together. Why was this happening?

It turns out that Rev A3A has a transient load issue when powered through the Replicape board. This was traced to the 5V DC-DC step down regulator. But even with slow changes in load, for instance ramping up the brightness on the display, the display would suddenly be cut when the load was high.

The Beaglebone has a power management circuit for the USB, a TPS2051 which has an under voltage lockout of 2V. This is probably what kicked in when a combination of switching noise and a sharp transient occurred.

Switching noise issues are not the easiest to debug. It doesn’t help (much) to add lots of capacitance to the output of the converter, it simply will not help reduce noise in the 200MHz range.

One solution to this problem was to limit the slew rate of the N-MOS on the step down converter by adding a resistor in series with the boost capacitor. This does decrease the efficiency of the converter by something in the region of 1%, but that is a small price to pay for a working USB power.

Below is a picture of a Replicape with a slew rate limiting resistor and one without. It is clear that the switching noise has been dramatically reduced with the slew rate limiting resistor.
Heat management is an important on such a small board, but a 1% reduction in efficiency should be acceptable.

image (3)image

A different solution would be to filter the noise by using an rc/lc filter or similar on the output, an RC snubber as they call it.

Sorry for the few updates lately, I’ve been in limbo trying to get ready for Maker Faire Rome. And the in the end I never did get the printer running in time for the event, haha! Still, it was a good show.

Ok, so this is the only hardware issue I am aware of, so hopefully CircuitCo will start production now.

Also, HipsterBot is dead! It’s now called Thing! You know, ‘cos it prints things? More updates in that later, I’m working on calibrating the printer now, so a few videos in a few days I’m sure!

Manga Screen Rev A2 – How to assemble

Populate the PCB

Remember to take your protein pills before such an endeavor. tools

Apply solder paste at strategic locations. Doesn’t have to be perfect, it will smear out in the reflow oven. solder-added

Into the oven it goes. This was actually after being in the oven. There are a lot of bridges here, these must be removed with a solder iron, flux and solder braid.
Manga Rev A2


This revision has an Atmega 32U4 AVR chip so there should be plenty of power to spare for anyone wanting to do some fancy touch filtering. The source code is in the Manga Screen repository.

Atmel stopped supporting FLIP for Linux on version 3.2.1, before they added support for Atmega 32U4, so in order to program the Atmega 32U4, I had to do the following:

sudo apt-get install  dfu-programmer

dfu-programmer atmega32u4 erase

dfu-programmer atmega32u4 flash MangaScreen.hex
6436 bytes used (22.45%)
dfu-programmer atmega32u4 reset

The reset command sets the program counter (PC) to 0×00 so the user program starts. If you hit the reset button at any time, the PC will jump to the start of the bootloader code.

USB Device

The USB driver is built on top of the LUFA library.  It should populate as a USB with two devices, one serial port and on Human Interface Device (HID). The serial port will accept commands such as “set display on”, “set backlight 128″, “set gamma yadayada”. perhaps also Upload/download EDID etc.  The HID  will of course be the touch screen.

Software implementation of a slave EEPROM chip

A couple of weeks ago we did not know that the EEPROM chips that are present in all displays and supplies the host with EDID info can also be programmed through the HDMI cable. Therefore we thought the best thing to do would be to let the AVR chip handle the role of the EEPROM. The problem was that the I2C controller on the AVR had been reserved for the touch screen controller so we had to use two GPIO lines and handle the timing our selves. But there was only one interrupt line available so we gave that the the SCK line, when actually it is the SDA line that initiates the start and stop conditions. So if anyone ever decides to do make the same mistakes we did, you might enjoy the EEPROM.c and .h files found in the repository. However, my advice is: Spend that extra 10 cents on a real I2C EEPROM chip : )

The (almost) final result

As you can see in the picture below, the screen works fine and dandy. Right now it is run through the DVI interface of my Ubuntu box at the native resolution of 480×800@60Hz. The idea is that this screen will be used primarily with the HDMI interface for BeagleBone Black.


I also made a video as soon as I got the screen working. Here it is:

Manga screen rev A2 from Elias Bakken on Vimeo.

The next step

That is to get the touch functionality working by porting the Linux driver for the mXT224 to the AVR.

Capacitive touch support for Manga Screen on BeagleBone Black

Manga touch

The first evidence of working touch functionality for Manga Screen can be seen in the video below.

Currently I have only gotten this working on Ubuntu 13.04 with LXDE as the desktop environment. The touch screen is controlled via I2C at the moment, so four separate wires are going to the display in addition to the HDMI cable. This has all been fixed in the Rev A2 of the Manga Screen where  all communication is done via USB.

There was quite a bit of work that had to be done in order to get the Synaptic ClearPad 3000 series touch screen controller working with X on the BeagleBone Black.

- Port the Synaptics driver from kernel version 2.6 to 3.8.13

- Recompile the tslib library module

- Recompile the tslib input module

- Write a device tree overlay

Below are the details for reproducing this. I’m sure a lot of steps have been left out, but at least this is better than nothing.

Compile the tslib module

The tslib driver consists of both a shared library and a Xorg input module.

I don’t know if this is normal or not, but it appears that the tslib xorg module is dependent on and is compiled in statically.The changes that were made to the module are currently in the git repository of the Manga Screen.

sudo make && sudo make install

If the default install dir is used, the .so-file has to coped to the location where the xorg input module expects to find it:

sudo cp /usr/local/lib/ /usr/lib/arm-linux-gnueabihf/

Compile the Xorg tslib input module

Here is a post explaining how to get the source code and recompile it:

Since there is no dependency information in the tslib lib (, you need to fix that:

I used the last solution.

Recompile the package:

sudo debian/rules binary

To re-install the debian package, do this:

sudo dpkg -i ../xserver-xorg-input-tslib_0.0.6-7build3_armhf.deb

The file /usr/local/etc/ts.conf is the overwritten, so remember to update it.

After that, you can compile with:

sudo make && sudo make install

You need to get the source for the tslib
ts_error(“line in %s is %s\n”, conffile, line);

 Rotation of screen with tslib does not work

With the tslib installed and the screen rotated, it turns out that X crashes, look:

I have been unable to get tslib 0.0.6 to work with Rotation=CCW on the screen. I get the error:

X: /usr/include/xorg/privates.h:123: dixGetPrivateAddr: Assertion `key->initialized' failed.

Instead I have had to hard code the rotation into the driver:

Rotation rotation = RR_Rotate_90;//rrGetScrPriv (pScrn->pScreen) ? RRGetRotation(pScrn->pScreen) : RR_Rotate_0;

Other errors: 

tslib: Selected device is not a touchscreen (must support ABS and KEY event types)

Make sure the right input device is selected try evtest /dev/input/event1. IF this reports these two symbols, it is the right device.

More info:

I’ve written up much of the process on the Replicape wiki as well, so if you want to reproduce this or expand on it, have a look at that as well:

Enable Device tree overlay on startup on BeagleBone Black

Update July 17, 2013: It appears that the reason the overlay can only be gotten from the firmware built in to the kernel and not from the file system (in /lib/firmware) is a bug in the latest kernels. Not sure which kernel numbers are affected by this, but it might work for earlier versions.

Ok, this should have been easy, but alas. Probably took me tree hours to figure it out. The key here is that loading firmware from file system does not work, you have to make it built-in and have it piggybacked with the kernel. This might be a bug because the file drivers/base/firmware_class.c does try to load the file, but fails, presumably due to insufficient rights. Go figure..

For this to work, you need a working “compile the kernel-setup”. Here is one example:

Then you need to add the device tree source file to the directory:


So for me adding a capacitive multitouch driver based on I2C, I add the file:

BB-SYNAPTIC-00A0.dts to that directory.

You also need to edit the file


and then add something like this:

			/* Always enable the Synaptic multitouch over I2C overlay */
			slot@103 {
				compatible = "ti,beaglebone-black"; 
				board-name = "BB-SYNAPTIC";
				version = "00A0";
				manufacturer = "Synaptic";
				part-number = "BB-SYNAPTIC";

If you do not want to recompile the kernel every time you want to add this line instead.

compatible = "kernel-command-line", "runtime";

You also have to edit the file kernel/firmware/Makefile

and add your device tree overlay as a cape:

# the virtual peripheral capes for Multitouch
fw-shipped-$(CONFIG_CAPE_BEAGLEBONE) += \

Recompile with action “uImage” and scp the uImage over to the /boot/ directory if you are on Angstrom. On Ubuntu, it’s the zImage that goes into /boot/uboot/.


Finally a working 4.3″ HDMI compatible LCD for BeagleBone Black!

image (2)

And it only took me 4 days to debug it!

This display is an LQ043Y1DX07 from Sharp, the same display that is in the HTC desire HD. The resolution is 800×480.
The display driver is an HX8363-A from Himax.
The receiver chip is a TFP401 from Texas Instruments which is really a DVI receiver. The reason for having a DVI receiver instead of an HDMI receiver is that having an HDMI receiver, you need to pay royalties.

The display needs a small amount of initializing through a 9-bit SPI interface. Currently this is done with a very inexpensive microcontroller, the MSP430G2231, the same that comes with the Launchpad. The current version can then be flashed using the Spy-bi-wire from a Launchpad.

The EDID information is read from an EEPROM chip. If you want to make EDID information yourself and do not have access to a windows machine, have a look at the python script I made:

The HX8363-A actually has a lot of registers for debugging the parallel RGB interface. You can check the state of the HSYNC, VSYNC, ENable and ClocK in addition to this you can check the status of the booster voltage and the result of the sleep out command.


The working title has been Replicape display, but from the next revision on I’m calling it Manga Screen

So why is this important?

4.3″ is fairly small size for an HDMI compatible display. There are several versions available in larger sizes at various sizes. The reason for this is that you need a high resolution to be compatible with the TFP401 PLL which is 25MHz. Now there are several LCD displays that are small, and have a large resolution, but newer displays with high resolution usually use the DSI protocol which is also impossible to get a hold of unless you are a member of the MIPI org.

The main use for this is together with the Replicape 3D printer cape, but I’m sure it can be used with a lot of other interesting projects as well.

What’s next?
Well, what’s a screen without capacitive touch? I also want the screen to be powered via USB and programmable via the same interface. If that works for the next revision, the idea is to get a batch of 50-100 made and we’ll see how it goes.

This is of course open source hardware and software:

Update: I tried it on a Raspberry Pi as well, and lo and behold, it worked! (Hope I’m not swearing in church here, BeagleBone, I still love you the most : )

raspiUpdate 2: The screen now has the right orientation:

Problems with BeagleBone Black and their solution

This page will be a running log for problems I encounter and their solutions.

LXDE under Ubuntu 13.04

On Ubuntu 13.04 I have not been able to log in and use the LXDE desktop environment in the normal manner. The LXDM (Lightwaight X11 Display Manager) did show the login screen and I was able to log in, but got a blank (or blue) screen after that. Writing “ps aux” showed that the [PreLogin] process was stuck on <defunct>. starting lxde manually with startlxde did work fine. The only solution I have found to this so far is instead installing lightdm. Should be as simple as:

sudo apt-get install lightdm lightdm-greeter-example-gtk

The lightDM display manager might be a bit big. An alternative is the Gnome Display Manager (GDM).

Unable to log in via SSH 

I’ve had a lot of trouble with logging in via SSH. One of the reasons is that the dropbear RSA key is corrupted. I think it might be related to having two BBBs.. From this thread on the google group:

rm /etc/dropbear/dropbear_rsa_host_key
dropbearkey -t rsa -f /etc/dropbear/dropbear_rsa_host_key

I’ve also had trouble with avahi-daemon.service active up and stealing all the resources. This can be seen by writing “top” and seeing that systemd takes up all the resources. To mask the avahi-daemon:

systemctl mask avahi-daemon.service

I have no idea what the consequences are, but this fixed the problem for me at least..

Rotate the screen
To rotate the screen (or change the orientation of the monitor if you will), add a couple of lines to the file


Driver "fbdev"
Option "Rotate" "CCW"

This goes in the section “Device”. The driver replaces the “modesetting”-driver.
CCW stands for counter clock wise.

This only works for X11, so if you want to rotate the framebuffer, add this to the kernel command line:


 Device tree compiler on Ubuntu 13.04

If you are getting the error:

dtc: invalid option — ‘@’

Robert C Nelson has a solution:”device-tree-compiler”package

wget -c
chmod +x

For some reason ‘which dtc’ did point to /usr/local/bin/dtc, but I still had to specify the whole path. Weird..

Unable to configure bonescript

This is the error message:

Job for bonescript.socket failed. See ‘systemctl status bonescript.socket’ and ‘journalctl -xn’ for details.

I noticed that the job was unable to start since there was already a version running. The solution was to kill the running instance:

ps aux | grep server.js

find the pid and run:

kill -9

Then try to start:

systemctl start bonescript.socket

This is probably not a permanent solution, but it worked for installing tslib that for some reason wanted to configure bonescript..