AVR audio spectrum monitor on graphical LCD

Running a Fast Fourier Transform (FFT) algorithm on an 8-bit microcontroller can be challenging. Here are a few reasons why:

  1. 8-bit microcontrollers are typically low-power devices with limited processing power. FFT algorithms require a lot of processing power, which can be challenging for these small devices.
  2. FFT algorithms require significant memory to store the data being processed and the intermediate results. 8-bit microcontrollers often have limited memory, making it challenging to implement a large FFT algorithm.
  3. 8-bit microcontrollers have limited precision when it comes to performing mathematical calculations. FFT algorithms rely heavily on floating-point calculations, which can be challenging to implement on an 8-bit microcontroller with limited precision.
  4. FFT algorithms are often used in real-time applications, such as audio processing or signal analysis. 8-bit microcontrollers may struggle to perform the necessary calculations quickly enough to meet the real-time requirements of these applications.

This is an original version of the previously posted AVR FFT analyzer. Chan developed it some time ago and is still a good reference for those willing to build or modify their own FFT analyzers.


On SG12232C graphical LCD, there are who parts displayed: waveform and spectrum. It looks fantastic and authentic when playing music. The program runs on AVR Atmega8 microcontroller clocked at maximum 16MHz frequency. The signal is passed through an 8th-order elliptic filter(anti-alias filter) implemented on MAX293. The hardest part of this project was implementing an FFT algorithm requiring lots of processing. But Chan has reached 9.6kHz sampling with 75Hz resolution, which is enough for visualization. Besides firmware author also provides fixed point FFT library optimized for Atmega microcontrollers so anyone can enjoy creating similar projects.


  1. The links to the firmware and the library are broken.

  2. Links are working properly. Just checked them.

  3. No – links don’t work for me either 🙁

  4. Hi, actually there is a problem when yo go direct to that direction, but you can copy and paste it in the and it works fine.

    I go to work now with this, this seems really cool.


Comments are closed