8x8 dot matrix spectrum light

A dot matrix spectrum light based on STM32F103C8T6 can be used as an accessory to the speaker to make your music melody move.

characteristic:

• Based on STM32F103C8T6, sufficient performance space is reserved to facilitate future expansion of functions.
• Red 2088B dot matrix, driven by MAX7219, convenient for programming
• Standard 3.5mm audio interface, powered by USB.
• An integrated power supply/audio interface is reserved for further DIY
• Spectrum analysis and display based on FFT, non-level display
• Adjustable gain to accommodate small signals
• Flip the display by pressing the button, making it easy to switch the position of the audio interface left or right.

Demo video:

https://www.bilibili.com/video/av82770831/

Welding and usage precautions:

• J1 and J2 jumpers are used to select whether the input signal is a left channel signal or a right channel signal. They cannot be left unconnected or shorted at the same time.
• The input voltage should not be higher than 5.5V
• R8 on the board is used to adjust the gain, the maximum gain is 10

Some notes on the source code:

• The text encoding of the source code is UTF-8. If garbled characters appear, please modify Keil's editor encoding settings.
• The source code is generated by STM32CubeMX and written based on the HAL library
• FFT uses ST's official DSP library, with a sampling rate of 20KHz and a frequency response range of 10KHz. Perform a 256-point FFT and display 8 points below 5kHz in the common vocal frequency range. Welcome everyone to develop again, such as using a longer dot matrix display

Proofing physical display:

Welding physical display