Getting started

To keep these instructions simple to use, I’m focusing on the assembly rather than an in-depth explanation.

If you have specific questions on “why” rather than “how”, please post on our Petoi robot forum at or write to [email protected].

You can support us by shopping at Petoi coding robot shop. Our social media (Instagram/Twitter/Facebook/GitHub) account is @PetoiCamp. Share your build with us by tagging #nybble #petoi #opencat so we can repost it for you!

1.1 Preparation

Prepare a clean desk and some small boxes to unzip the package. Take a picture of the kit contents in case you lost something later.

1.2 Tools and accessories

The actual kit contents and packaging method may be adjusted as we improve the product. This instruction will keep consistent with the current namespace.

Newest kit contents:

Early kit contents:

2.1 Cut body pieces off the baseboard.

8.1 Understand skills in InstinctNybble.h.

8.2 Example InstinctNybble.h

See the Getting Started guide.

There are 4 methods for users without any programming experience to control Nybble:

• Use the IR Remote Controller.

• Use .

• Use .

• Use .

If you have some programming experience or want to explore more advanced features, you can try the following methods:

• Use .

• Use .

• Use .

• Use .

To be written by 👉 YOU!

Share your knowledge and creativity with the community at https://www.petoi.com/forum.

There are two methods to config the NyBoard:

• The simplest method is to use the Petoi Desktop App. No programming is involved. You can play with some preset modes.

• If you have some programming experience, you can use the Arduino IDE. You will be able to modify the open-source codes for your new projects.

If you are using the BiBoard, please refer to this Arduino configuration instruction.

• The simplest method is to use the .

• If you have some programming experience, you can use the .

🔬It will make another textbook.

The controlling framework behind Nybble is OpenCat, which I've been developing for a while. You can read more stories from my on Hackster.io.

It's too much work for now 🤷🏻‍♂️ but you are welcome to discuss it with me on the forum or through email. Good thing is, I will keep the code compatible with future OpenCat models, and even ! Hopefully, the documentation will be completed during the processes.

Please refer to the in the Doc center.

The joints of the robot have to be calibrated before future use. Make sure all the servos are connected to the right spot on the circuit board in the right direction, the battery is powering (the yellow LED in the cat's logo is lighting up), and all the legs and head/tail are NOT attached to the servos so that the servos can rotate freely.

Our calibration routine will send a calibration signal to the main board and rotate all the joints to known positions. Then you can attach the legs close to the reference posture, and fine-tune the angles using the software.

There are three methods to calibrate Nybble:

• Use the mobile app .

• Use the .

• Use the .

3.1 Head and neck

3.1.1 Part list

3.1.2 Prepare ultrasonic sensor

We include an ODMed in the Nybble kit. It doesn't require soldering, but you need to trim off the plastic clip residue of the connection wire on the head's end.

You can download the demo code at

BelowT is a tutorial video:

With the basic distance detection and some proportional reactions, you can achieve the following demo:

3.1.3 Trim the servo arms for attaching servos.

Most of the servo arms on the model are trimmed from the cross-shaped arm I. Since there will be more unused straight arms, you can practice trimming with them first.

An alternative method to trimming is using a half-burned knife to cut the plastic parts off. Leave a little bit longer because melted plastic will have a rounded edge.

As we switched servo suppliers, the servo arms also changed a little bit (as shown below). To reduce confusion, the servo arm I can be used for most of the joints, just trim it accordingly. Servo arm K is used for the tail. Servo J can be omitted.

3.1.4 Assemble the head group.

Watch the to understand the assembling process, but don't assemble them all at once. Every part that connects to the servo's output shaft should not be fixed before calibration.

Notice how the servo wire is organized in the head.

3.2 Body

3.2.1 Part list

• NyBoard only

Note that without the Raspberry Pi, the NyBoard is mounted to the underside of y1 with the servo connections facing downward. In later versions, the y1 piece is designed to be symmetric so that both ends have two screw holes.

• NyBoard with Raspberry Pi

Use y1Pi to replace y1, and add Pi Stand. Pay attention to the location of the pink pieces. Note that with the Raspberry Pi, the NyBoard is mounted on top of y1Pi.

• Other controllers

I also included 5 x 1”/4 nuts for mounting other circuit boards.

3.2.2 Install the adjustable battery holder to the belly

After June 2022, we start to equip Nybble with a rechargeable Li-ion battery pack. It's also available at our if you get an earlier version of Nybble with a battery holder. Please add a note if you need the as well.

3.2.3 Assemble the body group

Pay attention to the long pins of the infrared receiver and FTDI port. They are designed to be bent in favorable directions. Don’t bend the pins too often or it will lead to metal fatigue. Observe the if you want to mount a Pi.

Assemble the body group as shown in the .

3.3 Shank

3.3.1 Part list

3.3.2 Attach the rubber to the tip of the shank.

The serrated structure on the tip of the shank is already good for walking. The rubber toe is optional to increase friction and soften each step.

3.3.3 Insert the servo into the slot on the shank.

Pay attention to the direction that the wire is twisted. The small dent on the long edge is designed to let the wire go through. Think about the symmetry of the four legs. Assemble the shank as shown in the .

3.4 Thigh

3.4.1 Part list

In later versions, we will use plastic pieces for thigh2.

3.4.2 Trim the servo arms for attaching servos.

The location has been shown in the section. The trimmed narrower servo arm is designed to be inserted into spring F.

3.4.3 Assemble the thigh.

Before closing thigh1 and thigh2, put the wire of the shank through the slot in the middle of the thigh. Think about the symmetry of the four legs.

When installing the screws, pay attention to the directions you insert them.

The servo arm should be able to slide in the track on thigh2 with subtle friction after thigh1 and thigh2 are screwed together. You can tune the tightness of screw C to achieve proper friction. If you need more control over the tightness:

• Scratch the track using a flat screwdriver to reduce friction.

• Apply a little paper glue to the track and let it dry to increase friction.

Assemble the thigh as shown in the .

3.5 Tail

3.5.1 Part list

3.5.2 Assemble the tail.

The screw D is installed in the third hole counted from the center of the servo arm K. Pay attention to the order that every piece is stacked. The wheel (tail2) should be able to rotate with little friction, and the whole tail should be able to tilt by a small degree.

Assemble the tail as shown in the .

4.1 Joint map

Nybble's servos are connected to NyBoard's PWM pins symmetrically and resemble the nerves along the spinal cord. Though Nybble doesn't have shoulder roll DoF, those indexes(4~7) are reserved for the full OpenCat framework.