Petoi Doc Center

FAQ(Frequently Asked Questions)

Arduino IDE

Cannot upload sketch, sync error.

The error that occurs when uploading the sketch is shown below:
This "not in sync error" indicates a bad connection between your computer and your robot. It could be:
Usually, it can be fixed by the following checks:
  1. 1.
    Install the CH340 driver, please refer to the section Driver for CH340 USB uploader​
  2. 2.
    Use the USB cable with the data function(the one included in the kit is good).
  3. 3.
    Select the correct board (Arduino Uno) and serial port
  4. 4.
    Connect the board and the programmer in the right pin order
The above steps are covered in the Doc Center.
Of course, you can also refer to the solution in the Arduino technical forum:


What do different sounds from the board mean?

Sound type
Short melody
Power on or reboot
The program starts successfully
Short beep
During use
The program receives a command
Repetitive short melody
During use and pausing the movements
The battery is low or unconnected

Why there are two calibration stages?

There are two calibration steps for different components.
Because the controller board has limited resources, we divide the program into two stages.
In the first stage, we upload the program and large data to the onboard EEPROM (hard disk) and use the remaining programming space to calibrate the IMU, a sensor that measures the body orientation. The board should be leveled and untouched during the (IMU) calibration.
In the second stage, we upload the standard functional code. For the first-time configuration, we need to enter the (joint) calibration state and attach the legs in the right direction.
If you use the Arduino IDE to set up the board, you will handle those stages explicitly. The Petoi Desktop App can finish the two-stage uploading in the background. The smartphone app can work only with an already configured board. Its (joint) calibration is only for attaching the legs.

When using the smartphone app, I found that Bittle was walking very slowly.

Try turning off the Gyro in the mobile app, as shown in the following picture:

When using the smartphone app, Bittle cannot turn back up now.

Try turning on the Gyro in the mobile app, as shown in the following picture:

Bittle doesn't walk very stable.

  • Make sure you calibrate the joints with the included L-shaped tuner and understand the references
  • Remove the rubber toe covers
  • ​Turning off the Gyro will make slow gaits more stable

If to buy the preassembled bittle does it still have to be calibrated?

Yes, you still need to use the desktop app or smartphone app or Arduino IDE to fine-tune the joints.

If to buy the main board alone, do you have to buy a separate software program to make it work?

Our main board is specifically designed for our robots. The code is free to download on GitHub.

Could Python be used to control the robot?

You can use python to control the robot. The scripts can work either on your computer and connects to the robot wired or wirelessly.

Can your little robot (Bittle / Nybble) function on its own? Or, it only works with the commands I give it? Also, can it learn?

It follows your instructions via the infrared remote, smartphone app, or desktop app. It can also do random behaviors if you upload the random mode. Best of all, the program is open source on GitHub and you can refer to the relevant technical documents to create new skills for the robot.


How can I easily install the springs into the upper legs of Bittle?

Please check out the forum post discussing installing springs with varies tools.

I can't find the toe covers. What are the toe covers for?

The toe covers are for special experiments that require more friction. They are not required for regular walking and performance. We have removed them from the standard kit recently and you may order them as optional accessories.

Some frame structures are broken. Where can I get replacement parts?

You may contact [email protected]. Show the picture of the broken pieces and explain how they broke. You may find the 3D-printable files or get a replacement directly from us.

Where can I get the bone shown in Bittle's picture?

The little bone is included in the Intelligent Camera Module box and it is not being sold separately. You may download its 3D-printable file at:​

Does it come with a battery or do you have to buy a lithium battery?

Both Bittle kit and pre-assembled Bittle include one Lithium battery with a built-in charging circuit. You may add more spare batteries.

Does Rasberry Pi require any additional components?

You can solder the 2x5 socket on the NyBoard and then mount the Rasberry Pi on the NyBoard.

How to debug the servo?

Quick fix the servo motor engagement

In some cases, the motor's output gear may disengage with the following gear. It will result in an abnormal buzzing sound inside the servo. You can take off the bottom of the servo and push the motor inward very hard until you hear a clicking sound.

Driver for CH340 USB uploader

Can I use Codecraft/block-based coding with the basic Bittle package or do I need to purchase add-on components/modules?

Bittle can be programmed with a Scratch-like web-based IDE Codecraft. You may find some complementary materials: online help and curriculum.
Note that CodeCraft hasn't provided support for our 2.0 version. But you may roll back to the supported version within CodeCraft or through the desktop app.
You don't need to buy add-on components to use the basic functions in Codecraft. However, several extension functions require add-on components. If you are comfortable with coding with Arduino, you can have a much wider selection of third-party components.
Recently, we developed an extension library Petoi Coding blocks, which can be imported into another Scratch-like web-based IDE Mind+. We strongly recommend you use this extension library.