STM32CUBEL4 datasheet(22/37 Pages) STMICROELECTRONICS

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Demonstration functional description

UM1919

22/37

DocID028080 Rev 1

4.4.7

Guitar tuner

Overview

The Guitar tuner module application allows to demonstrate the perfect integration of an

acoustic Guitar tuner audio library. It uses the audio recording capability of the digital

microphone embedded on the STM32L476G discovery board.

Figure 18. Guitar tuner application menu selection and display

Status could be any of the following display outputs:

•

“

“: audio sample invalid. Ensure that STM32L476G discovery board is close to the

guitar

•

“OK“: string in tune

•

“++“: string needs to be tightened

•

“+“: string needs to be tightened but close to be in tune

•

“--“: string is too tightened

•

“-“: string is too tightened but close to be in tune

Features

•

Standard tuning type of 6 acoustic guitar strings

•

Input 16-bits PCM data with a sample rate at 8 kHz (mono)

•

Precision lower than 0.5 Hz

•

Real time display every 256ms

The standard tuning method is based on the following expected frequencies per string:

Table 3. Frequencies per string

String 1 (Hz)

(the thickest

string)

String 2 (Hz)

String 3 (Hz)

String 4 (Hz)

String 5 (Hz)

String 6 (Hz)

(the thinnest

string)

E1 = 82.41

A1 = 110

D2 = 146.83

G2 = 196

B2 = 246.94

E3 = 329.63

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