【Course Design】Kalimba Electronic Piano

source of creativity

You can often see the musical instrument shown in the picture below on video websites. This instrument is called kalimba, and it makes sound by the vibration of metal shrapnel. This project will guide you on how to design a kalimba electronic keyboard.

Project proposals

The core of an electronic musical instrument has two major parts, the key system and the sound system. The key system determines the feel when playing, and the sound system determines the expressiveness of the instrument. In order to simulate the feel of metal keys, we used the travel switch shown in the picture above to make the keys. This kind of travel switch also has a metal spring on it, which feels very consistent with the real kalimba. The sound system uses PWM to drive a buzzer to generate sounds of different frequencies.

Project software and hardware design

The system structure diagram of the entire project is shown below:

The main control chip is STC15W204, packaged in SOP16. One of the 14 GPIOs is used as a PWM driver buzzer, and the other 13 GPIOs are connected to 13 keys, which can be made into a 13-tone kalimba. The 3D rendering is shown below:

The software is also relatively simple. The core idea is that when I press a button, it controls the PWM to output a square wave of the corresponding frequency to drive the buzzer to make a sound. The program block diagram is shown below

Generally, buzzers have a response frequency range. I tried several common buzzers on the market and found that the sound is relatively clear in the range of 500Hz - 1300Hz. If the frequency is lower than 500Hz, a hoarse sound will appear. If the frequency is higher than 1300Hz, the sound intensity will decrease. Moreover, the tone of the buzzer is relatively simple and can only emit a beep beep sound, so the performance of this version of the electronic keyboard is average. Fortunately, the production process is relatively simple. Interested readers can try to make one by themselves.

Project design knowledge points

1. Schematic diagram and PCB design 2. Welding skills training 3.51 Microcontroller minimum system 4. Application of PWM 5. Application of key input

Expected classroom results

The main purpose of this project is to stimulate students' interest in learning and improve students' enthusiasm for participating in class.

By producing a real and interesting work, students can learn the knowledge they need to learn in the process and realize the application value of the knowledge they have learned.

Make and present videos

Homemade kalimba electronic keyboard, which can be connected to mobile phone GarageBand MIDI Boy via Bluetooth [the first musical instrument for science students]_bilibili(゜-゜)つロCheers~-bilibili