1. Project Introduction

This product is an electronic musical instrument. The main control chip uses ESP32. Its appearance imitates the shape of the ancient Chinese musical instrument "Xun". It has six buttons, simulating the six finger holes of the instrument, and can play 13 tones. Through the Bluetooth MIDI protocol, connect the mobile phone "Zileban" APP and make sounds on the mobile phone ~

Bilibili video demonstration: https://www.bilibili.com/video/BV1RT411u7S9

2. Design ideas

The entire product can be divided into four modules, as shown below:

Its working principle is that the microphone detects the size of the blowing airflow, converts it into voltage, collects it through the ADC, and controls the volume. Different key combinations identify different notes. Bluetooth is responsible for sending note and volume information to the mobile phone and making sounds on the mobile phone.

The microphone is installed as shown in the picture above. When playing, blow into the kitten’s ears.

The specific fingering is as shown in the picture above, and a total of 13 notes can be played.

The board is equipped with 7 WS2812 lamp beads to indicate the Bluetooth connection status and airflow intensity.

The hardware structure adopts the form of upper and lower floors, connected by 4 copper pillars in the middle. The copper pillars also have 4 electrodes for communicating with the upper and lower floors.

The size of the board is controlled within 10*10, and you can go to Jialichuang for free proofing~~~

3. Welding guidance

In order to continuously debug and optimize the equipment during the production process, some pads that were not used in the end were reserved. In addition, the audio output function has not been implemented yet, so this part does not need to be welded. The parts that need to be welded are as shown in the figure below:

4. Software source code

The software is written in C language and needs to be compiled using Espressif's ESP-IDF. Open source address: https://github.com/ospanic/Totoro

It doesn’t matter if you don’t have relevant programming knowledge. The compiled firmware is provided in the attachment . Just follow the figure below and use flash_download_tools to burn it into the device:

5. How to use

The first step is to install the " Zileban " APP on your mobile phone

Search for "Zileban" in the app market, download and install it

The second step is to set the device mode

The pronunciation methods of the Android and iOS versions of the software are different, so you need to adjust the device mode according to your phone type .

Flip the switch of the device to " on " and start the device. The 1357th light will flash once at the moment of startup, and then the 7th light will flash blue, indicating that the device starts normally .

The device defaults to iOS mode. If your phone is an iOS system, there is no need to adjust and jump directly to the third step.

If your phone is the Android version, you need to follow the following steps to adjust:

After the device is started, press and hold the " Flash button ", and then press the " Mobile Mode Switching Button ". The device will switch modes. If the 3rd light lights up blue, it means switching to Android mode. If the 3rd light lights up green, it means it has switched to Android mode. Switch to iOS mode.

The device mode settings have a save function, so there is no need to repeat the settings next time. When the power is turned on, the No. 1357 light is green, indicating that the current mode is iOS, and the light blue, indicating that the current mode is Android.

The third step is to connect the mobile phone to the device

After the device is powered on, the seventh light flashes blue, indicating that it is waiting for connection.

At this time, open the "Ziyueban" APP on your mobile phone, click "Performance", and then click the connection logo in the upper right corner.

Note : 1. Connecting the device is done in the "Zileban" APP, not in the phone settings.

           2. Only after opening the Bluetooth and positioning permissions to the "Zileban" APP can the device be searched correctly.

In the page that opens again, you can see the currently connectable devices and click on the link.

Note: iOS phones need to click "Bluetooth MIDI Device" on the above page to see the list of connectable devices.

Step 4: Select the tone and play

Turn up the volume on your phone, select "Local" on the performance page, create a track, click to enter, then add a tone according to the prompts, select the tone and play:

Currently, the device provides a variety of timbres to choose from, and readers can explore them on their own.

Raise and lower tone operation

The device defaults to the key of C, and the key can be raised or lowered by doing the following steps:

After the device starts normally, hold down the Flash key and tap the rising key. The device will rise a semitone and the 6th LED will light up red.

Hold down the Flash key and tap the flat key, the device will drop a semitone and the first LED will light up red.

The above settings can be saved even when the power is off!