Audio waveform and frequency spectrum display program.  Audio input is from an
Electret mic with pre-amp circuit.  Frequency response is only around 8kHz.  No
anti-alisaing filter so, may get erroneous values at higher frequencies.

Although this runs on Arduino framework, a higher power MCU is needed than
standard Arduinos.  In this case using an STM32 Nucleo32 dev board was used NUCLEO-L432KC.  If you cannot  find this board, then another STM32 with at least 80MHz clock rate is fine.

Hookup

DISPLAY

CS -> D6

DC->D9

RES->D10

SDA->D11

SCL->D12

Vcc - LEAVE UNCONNECTED

MIC - output ->A0

Switch - GND and to D4

I used platform.io for development.