1. Electrical traditional Chinese Instrument - Xun
ECE 445, Team 9
Hongyi Li, Chi Zhang, Yujie Zhou Dec 10, 2018

2. Introduction An acoustically similar wind instrument to real Xun
An innovative way to learn and practice instrument playing

3. Objectives Play out different notes under different hand gestures
Change loudness under different blowing strength
Respond quickly to players’ change in hand gestures and blowing

4. Block Diagram

5. Project Design Hardware:
Power supply, buttons, air pressure sensor, micro controller, SD card, low-pass filter, audio amplifier
Software:
Program on the microcontroller that play the right piece of music on the SD card based on player’s input

6. Physical Design

7. Power System Function: Deliver power to the rest of the circuit
Three major parts:
Each part is composed of a 9V DC Alkaline battery and a linear regulator.
Each part outputs 5V DC voltage to the rest of the circuit.

8. Power System - Current Verification

9. Sensor System
The sensor system is used to take inputs from the player.
There are two main player inputs that we need to monitor and utilize.
Player’s hand gestures.
Player’s breath.

10. Sensor System - Buttons
Six button-like switches to sense the player’s hand gesture.
Function: Generate voltage signals of different magnitude, high or low, when the button is pressed and released.

11. Button Schematic Output is LOW by default.
Output is HIGH when pressed.
Schematic for one button

12. Sensor System - Air Pressure Sensor
Get air pressure as input.
Output voltage between 0 to 5V, 1.8V in lab condition.
Steady output.

13. Air Pressure Sensor Verification
Connect air pressure to the microcontroller and wrote code to read the air pressure sensor input.
Put the air pressure at rest in the 2070 design lab and record its output voltage.
Take 100 samples, and 97 of them were V, 3 of them were V.

14. Air Pressure Sensor Verification
We let the player blow into the air pressure sensor and we got an output voltage range from V to V.

15. Control System Input: Signals from the sensor system.
Output: Music signals stored previously in the SD card to the audio output system.

16. Control System - SD card
The SD card stores all the music recordings of the real xun. All the music recordings should be in the following format:
8-bit resolution
16 kHz sampling rate
mono channel
PCM unsigned 8-bit

17. Control System - Microcontroller
Connect to all sensors
Read data stored in the SD card
Select data based on sensors’ input and give it to audio output system

18. Microcontroller
- flow chart

19. Control System Verification
verification code:
Data transfer time:
The data transfer time is approximately 7ms.

20. Control System Verification
Note Correctness:
Real Xun’s Sound
Our Xun’s Sound
483.31HZ
484.87HZ

21. Audio Output System Achieve two tasks:
Filter the signal to reduce noise
Amplify the output music signal so that it can be played on a speaker

22. Audio Output System - Filter
Keep components of the signal under 16 kHz the same
Attenuate the components of the signal above 16 kHz

23. Audio Output System - Audio Amplifier
Can amplify the signal 40 times in magnitude

24. Audio System Verification - Filter
Pass signals at 1kHz
Peak-to-peak voltage: 3.44 V
Attenuate signals at 55kHz
Peak-to-peak voltage: 1.49 V

25. Audio System Verification - Amplifier
Testing: Achieve 40
times of amplifications of a signal with 100mV (peak-to- peak)
Output signal has peak-to- peak voltage of 3.99V

26. Review: Design and Verification
Components that we tested and verified successfully:
Alkaline batteries and linear regulators
All six buttons and the air pressure sensor
Microcontroller and the uploaded program
RC filter for noise attenuation
Audio amplifier

27. Video

28. Conclusion Our project meets all high-level requirements:
Output correct sound pitch
Output four different volume levels
Response time is tolerable.

29. Future Work Obtain higher similarity with the real sound of the xun
Improve sound control with respect to air pressure sensor
Implement an instructive LED system

30. Thank you!