Bakiwi Assembly Documentation

Clean and wipe your workbench and get all the tools needed as denoted in the list or shown in the picture.

Prepare your workbench for soldering. We recommend using a fine tip and thin solder.

Adjust the soldering station for sufficient heat depending on the solder you use. Some stations show the current temperature, make sure to let the iron pre-heat before starting. If soldering 'feels' very sticky, you might have not the correct temperature (too cold) or the flux in the molten solder has already evaporated. Also, ensure to always use a clean solder tip, preferably using a dry cleaner (metal pot cleaner) as it does not cool down the solder tip (in comparison to a wet sponge) and the cleaning result is generally better.

Keep the electronic parts together as they are tiny and get lost easily when they are accidentally dropped from the table.

So now you should be prepared for soldering the first part. Insert header pins for the Nano-Board as shown in the picture.

You can use a breadboard, if available, for stabilizing the pin headers and keep them aligned and perpendicular during soldering.

Solder the pins one after another. After soldering the first pin, double-check for alignment and correct it if needed. Otherwise, continue soldering all 30 pins.

The result should look like this. Sufficient solder looks shiny and volcano-shaped. If it looks like a water drop or ball then there is too much solder. You can remove it by cleaning the tip and put the soldering iron again to the pin. Alternatively, use de-soldering braid to remove excessive solder.

If the solder point has a weird shape or noses, then there was probably not sufficient flux available in the melting process, use a little fresh solder to make the solder point shiny again.

Get the two 1 Kilo-Ohms resistors and the motherboard. Don’t get irritated as the color might be different than shown in the picture.

Bend down the resistors' leads very close to their ends and trim the leads as shown in the picture.

Insert resistors as depicted and printed as R1 and R2 on the board’s silk screen. Make sure that the resistors are soldered very closely to the board.

Trim the leads after soldering using the side-cutting pliers.

Get the two capacitors. They completely differ in size and form.

Insert the ceramic capacitor (small) first as it has a lower profile. Again, make sure that the capacitor is soldered very closely to the board.

The electrolytic capacitor has a polarity and its leads must not be mixed up. The shorter lead is minus, the longer lead is plus. Make sure polarity is correct as denoted on the board and shown in the picture. The capacitor must be laid on its side since the Nano-Board will be mounted above it.

Get the LEDs. Their colors or shape can be different depending on the version of the assembly kit.

The LEDs also have polarity. Again, the shorter lead is minus, the long lead is plus. Make sure polarity is correct as denoted on the board and shown in the picture.

Get the switches. The silver/black one is a tactile switch, a button so to say. The other one (blue/white) is a slide switch.

Insert and solder the slide switch and button. When inserting the tactile button, look out for correct orientation. There is only one correct way and you probably need to gently press the part into the board. You feel a little click when inserted correctly. The orientation of the slide switch is pretty clear and can be installed in both ways. After soldering, make sure that the slide switch is turned off (as marked on the board).

The next thing to solder is the sockets for the Nano-Board. The sockets in your package might have more than 15 slots, so you need to trim the socket to exactly 15 slots and use sanding paper to make it even. Be careful when trimming the sockets, they might break easily. You have to cut directly through the 16th socket pin, not between pins as this might accidentally break the 15th pin as well.

Then insert the socket and solder the 30 pins. For each half of the socket, make sure the sockets are aligned perpendicular and closest to the board. Otherwise, the Nano-Board might not fit into the socket.

Get the servo pin headers and insert four times the 1x3 pin servo header to all four corners of the board, next to the screw holes. Again, make sure the pins are perfectly perpendicular to the board, otherwise, the servo connectors might interfere with the sockets of the Nano-Board.

Get the four potentiometers (10 KOhms) and the associated knobs (might have a different color) and insert the knobs in such a way that the shiny metal part of the potentiometer is on the back. When inserting the knobs, make sure the arrow is pointing upwards. Check for correct neutral position (pointing to the top), e.g. when turned fully to the left end stop the arrow should point in the lower left corner and when turned fully to the right end stop, the arrow should point to the lower right corner.

Insert the potentiometers as shown in the picture, turn the board and solder them.

Get the wires (approx. 10 cm each). The might have different colors than depicted or the wires come as a flat cable.

Strip the insulation of all the wires' ends, approx. 3-5 mm, twist the ends a little and pre-solder the wires. Pre-soldering is useful to better insert the wire into solder holes.

The result could look like this.

Insert the wires in the denoted order and solder them to the board.

Twist pairs of wires, each pair will be associated with a single battery pack of two cells. If you have a flat cable, you can split them in two pairs of wire.

Turn the leads of the battery pack a little upwards so they do not stick out over the part.

Check polarity of the battery pack (it is denoted inside the packs).

Solder wires to the battery packs as shown. Double check for correct polarity. According to your cable colors the order should be (B1- B1+ B2- B2+) with Bx denoting the battery pack (1 or 2), as denoted on the board/schematics.

So, congratulations. You did it. You finished soldering. Yay. \o/

Next thing to do is to trim the pins to be as short as 1-1.5 mm.

Dispose the trash material correctly. Metal, plastic and paper parts can be recycled and should not be put to residual waste.

Now it is time to first power-up your freshly soldered Bakiwi robot.

Get a computer and browse to https://www.arduino.cc/en/Main/Software and download and install the latest Arduino IDE according to the description on the Arduino website. If you already worked with Arduino boards and have the IDE already installed on your computer, you might consider updating to the current version as it might be required to detect the Bakiwi robot’s control board in the Arduino IDE. This manual was tested with version 1.8.8 without any problems or modification needed.

Download the latest Bakiwi firmware source code folder with name so2walk from https://github.com/ku3i/Bakiwi.git and save to your local hard drive (hit the Clone or Download button on the Github website).

Alternatively, if you are familiar to a Linux terminal and want to use the source code version system Git, type

to clone the code repository to your computer. Optionally, if Git is not already installed on your Linux machine, type

If you have question on using Git (e.g. for other operating systems), please refer to https://www.git-scm.com/.

Open the Bakiwi firmware’s source code in the Arduino IDE (file→open) and hit the compile button (it looks like a checkmark, it’s somewhere in the left upper corner). When compiling works without complains from the IDE then all the code dependencies seem to be fulfilled on your machine and the compiler was able to create the binary code to be run by the microcontroller on the Nano-Board. The firmware source code file is located in:

Remove batteries again and connect the Nano-Board to your computer via USB (mini)-cable. The board should immediately power-up again as you connect the cable.

Next you need to select the target board and processor. The Nano-Board is compatible to Arduino Nano and hosts an 8-bit ATMEGA328p microcontroller. After setting the board via Tools → Board → Arduino Nano you also have to select the correct microcontroller and Bootloader combination via Tools → Processor → ATMEGA328P (Old Bootloader). If the old-bootloader option is not available in your Arduino IDE you may consider updating to the current version.

Please note: The board uses an USB-to-Serial chip-set called "CH340" which, depending on your operating system, may need some sort of driver to be installed.

You can now upload the code by hitting the upload button (an arrow to the right). If everything has worked out fine, the motherboard’s LEDs should blink in a periodic pattern.

For testing, follow these steps:

The LEDs should again be blinking periodically. The four knobs modify the properties of the neural oscillator: Frequency, Phase and Amplitude (2x).

There are four 3-pin headers that allow for connecting motors. In the current version of the code only two of them are sending motor commands (the two next to the USB connector). The others you can use for connecting additional motors or sensors, when you modify or extend your robot or its code.

You find the knob which modifies the frequency in the right upper position when holding the board with the USB connector upwards while looking from the Nano-Board side. Try out modifying the frequency and watch the LEDs blinking accordingly. The blinking LEDs corresponds to moving motors later. So the motors will change direction with the same frequency as shown by the LEDs.

For each motor the oscillation is tapped at two different positions, so that you can create patterns that are either more in-phase or anti-phase. The right lower knob modifies the phaseshift between those taps. Try out the phase knob and so how you can create different blinking patterns.

When powering-up, your Bakiwi is in pause mode. You can now start the motors by hitting the tactile button. The motors will now begin to move according to the frequency and phaseshift you set.

The other two knobs (on the left side) can be used to modify each motor’s amplitude. You can either decrease the amplitude by turning them to the right until the motors fully stop or you can increase the amplitude to a certain maximal value by turning them to the left.

Please note that a mixture of large amplitude and high frequency at the same time can probably not be accomplished by the motor since every physical device has some sort of inertia.