Embedded Device for Audio Signal Analysis and Classification of Musical Notes Using Machine Learning Blog Post

การทำงานในช่วงเดือนกรกฎาคม - สิงหาคม

Results of operations in the past period

1. Experiment of summing 2 inputs and 1 1.5V DC offset

Working with microcontroller requires voltage that is more than zero, so we set 2 inputs Vpp = 1V, then sum the 2 inputs with 1.5V DC offset.

• Input Frequency 700 Hz with yellow line
• Input Frequency 1400 Hz with light line
• 1.5V DC Offset with pink line
• Output(Inverted) with blue line
  

2. Test the use of various equipment and functions to make sure they can actually be used.

We use ESP32 as a microprocessor. It has 3 ways to send the audio data.

• Bluetooth
  Test sending data via bluetooth by try sending data via Bluetooth from ESP32 to PC and experiment by sending the value i2s_buf which will be a buffer that stores sound sampling data for further processing. There are 16 i2s_buf values in total. From the code :
  
  Send data i2s_buf and count down 3 seconds, then send data again, repeating indefinitely. Showing Program for receiving data: Bluetooth serial terminal :
  
  Whem the Bluetooth connection status is Connected, which means the Bluetooth connection is successful. Show :
  
  Code example for reading data through INMP441 and I2S protocol :
  
  By setting the sample rate = 2000 Hz (experiment with low frequencies first to see if the results are correct according to the input that came in or not).
  Make settings as follows:

  • Resolution = 16 bits
  • Buffer length = 512
    Read data through I2S MEMS and test results.
    
  • The results obtained is to do an exam that Is reading the data 1 time successful or not?
  • If successful, bytes_read is displayed, which is the amount of data that can be read.
  • i2s_buf[0] is the data in the first buffer of data reading at that time.

• Connection cable

• Wifi