OST (OpenStoryTeller) is an Open Source alternative to Lunii, the green (or blue!) audio story teller which is loved by all the kids around!

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The aim of this project is to offer a reparable/hackable alternative to the commercial story teller. Here you will find electronics boards, firmware and mechanical design to create your own alternative based on popular chips (ESP32/Arduino ...) that will make the system easy to build and repair.

1. Why this project

Lunii is a commercial story teller little box for kids : they listen to audio stories and they can change the path of some of them by choosing elements and characters. There is a tiny screen used only to display images during the choices.

Kids are fond about this box! As parent, it is your best friend during travels :D

Well, here comes the goal of this project. The story box is quite good, especially the mechanical part: the touch sensation is very soft and the size nearly perfect (a thinner box is better). You can buy and add more stories through a software called LuniiStore connected to the USB port of the box. The quality of stories are very good.

The dark side of the commercial box is the fragile electronics parts:

  • Problems come often from the buggy firmware
  • the USB port and the LCD screen defective electrical connections (using a USB-C should be better!)
  • the battery fastener is poor quality (and the LiPo 700mAh is quite short and not working after 3 years, but this can be easily changed)
  • Limited options to create your own stories (everything is opaque)

Having an electronics product that does not work for one day is a drama for kids. That's why I decided to create my own version of a story teller box.

The goal of this project is:

  1. Provide resources (firmware, BOM...) and guidelines to build your own hardware
  2. We bot not provide custom boards: USE EXISTING BOARDS on the market. Using existing parts will be resilient and easy to repair
  3. Provide STL and 2D/3D plans to build your own enclosure (3D-printed, CNC ...)
  4. Provide a basic firmware, open-sourced, that can be easily hacked to fit your needs

2. Architecture

Here is the main diagram which is very generic.

3. Software

A PC and Android app is under development. Beta 1 is available! Source code and pre-build version for Windows can be downloaded!

Please provide feedbacks.

4. Firmware

The firmware will be very easy to port to any hardware platform: we will use hardware abstraction layers!

5. Mechanical parts

The form factor will be completely different: the goal will be to provide a MINI story teller box.

/!\ Work in progress /!\

The goal here will be to provide 3D mechanical parts to print by yourself to you can easily build and repair your box at home.

6. Project source code, BOM, guidelines and datasheets

Portable Network Graphics (PNG) - 467.42 kB - 10/06/2020 at 07:43


Adobe Portable Document Format - 203.17 kB - 10/06/2020 at 07:43


JPEG Image - 29.25 kB - 10/06/2020 at 07:32


Portable Network Graphics (PNG) - 45.66 kB - 10/06/2020 at 07:32


  • 1 × Arduino MKR Zero
  • 1 × LiPo Battery 1000mAh
  • 1 × Audio Codec
  • 1 × LCD Screen 320x240
  • 1 × Enclosure

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  • Arduino MK​R Zero board, ST7789 display and generic firmware

    Anthony Rabine08/11/2022 at 14:28 0 comments

    Hello there,

    Here are some news.

    I merged several repositories into a single one to achieve the generic firmware organization. The new repository is here

    The target Arduino MKR Zero is now integrated in the build system, it is the second architecture supported after the Longan Nano. Currently SD Card and display are functional (using ST7789 display driver).

    In the next step, my goal is to add some buttons, and especially a rotary encoder. Then, the sound!

  • Windows reader application is available for testing!

    Anthony Rabine04/13/2021 at 09:25 0 comments


    I have just delivered the first beta version of the Windows player software. Just specify the packs path and enjoy :D

    The firmware is on the way, the first version should be available in few months.

  • MCU change (RISC-V) and Audio is working!

    Anthony Rabine04/06/2021 at 13:29 0 comments

    Hello makers,

    The Open Story Teller project continues with a major change: we switch the main MCU board from the Arduino MKR to a RISC-V  based board from Sipeed : Longan Nano. The MCU is a STM32 clone, the GD32 family.

    This change is due to the price of the MKR ; but it can be a reliable solution for another variant of the project. The GD32 is also available with different boards such as a SeeedStudio or Lyligo brand. The SeeedStudio is very nice and has many GPIO : it may be a good candidate for our final product.

    As always, the source code is available on github:

    The next part will focus on the display and the buttons!

  • Decoding pack resources is now possible

    Anthony Rabine12/21/2020 at 12:42 0 comments

    Thanks to the effort of the community, the last version of the official Lunii which is built using a STM32 micro instead of a Sonix has allowed to find the algorithm used to encode resources files.

    I have integrated in the software player, and now the image is displayed correctly!

  • SD Card reader and Music is playing

    Anthony Rabine11/10/2020 at 16:00 0 comments

    Good day!

    My tiny mock-up is now nearly complete: I am able to play a music file stored on the SD card.

    One bad news: the sound is very very bad, it has many glitches.

    I have tried two boards, one with an audio jack output and the other a simple 4 Ohms speaker output. I have the same result, the sound is crappy. 

    Investigations is on going!

  • First firmware: Blinky, SWD debug Serial output

    Anthony Rabine10/30/2020 at 10:59 0 comments

    Hello there!

    So this week we have chosen the firmware library stack and tested some useful debug tools.

    So far, we have now:

    1. A SWD debugger, a JLink probe and the Ozone tool for visual debugging
    2. A nice IDE: QtCreator
    3. A good build-engine: CMake
    4. A well-tested and simple library: Arduino SAMD21

    We have also successfully tested:

    • A LED blinky test
    • A Serial output (Hello, World) through the USB port

    Now, we are prepared to develop the entire application code. We are going to start with the SD-Card reader in the following weeks.

View all 6 project logs

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