The ChromaticTuner application was developed for the 2009 STM32 Primer2 contest. It demonstrates the STM32 Cortex-M3 signal processing capabilities.
16 bits audio samples are captured from the STw5094A audio codec at 16kHz. A sub-sampling pass (x1 to x32) is done to adapt the targeted frequency accuracy. Thanks to the STM32F10x DSP library, samples are processed with a real-time 4-radix complex FFT (1024 points). Once the fundamental frequency is extracted, the corresponding note and the accuracy is displayed on a vu-meter.
By clicking on the 'scope' toolbar ChromaticTuner is able to display to screen the captured audio graph (time domain) and it's real-time spectrum (frequency domain).
A short help is available clicking the 'info' button.
1.0 : initial revision
1.1 : changed the FFT to a 1024 points one to improve the measured frequency accuracy to 1 Hz