OverviewWith Arduino, we can generate sounds in several frequencies using a simple buzzer or speaker.Arduino's API comes with specific functions for this given task: tone() and noTone() [1].In this project, we'll use a bunch of pushbuttons in order to create a musical keyboard!The goal is to produce distinct tones for each of the 6 available pushbuttons.These six tones should correspond to these musical notes: C5, D5, E5, F5, G5, and A5.Yeah, B5 is missing due to lack of space in my small 400-contacts breadboard.Note frequencies were retrieved from Physics of Music Notes (MTU Physics) [2].Components1 buzzer (or speaker)6 pushbuttons6 current resistorsJumper wiresBreadboardArduino Uno compatibleSchematics[https://github.com/hjort/arduino-toys/blob/master/buzzer/MusicalKeyboard.fz]Source Code#define BUTTON1_PIN 3#define BUTTON2_PIN 4#define BUTTON3_PIN 5#define BUTTON4_PIN 6#define BUTTON5_PIN 7#define BUTTON6_PIN 8#define BUZZER_PIN 9#define FIRST_BUTTON BUTTON1_PIN#define LAST_BUTTON BUTTON6_PIN#define FREQ_C5 523.25#define FREQ_D5 587.33#define FREQ_E5 659.25#define FREQ_F5 698.46#define FREQ_G5 783.99#define FREQ_A5 880.00const float freqs[] = {FREQ_C5, FREQ_D5, FREQ_E5, FREQ_F5, FREQ_G5, FREQ_A5};void setup(){ for (int pin = FIRST_BUTTON; pin <= LAST_BUTTON; pin++) pinMode(pin, INPUT);}void loop(){ int button = 0, freq = 0; for (int pin = FIRST_BUTTON; pin <= LAST_BUTTON; pin++) { if (digitalRead(pin) == HIGH) { button = pin - FIRST_BUTTON; freq = int(freqs[button]); tone(BUZZER_PIN, freq, 100); } } delay(100);}[https://github.com/hjort/arduino-toys/blob/master/buzzer/MusicalKeyboard.ino]Project in Action[https://www.youtube.com/watch?v=BgP_79HdVc0]ReferencesArduino Language Reference Guide - Tone: https://www.arduino.cc/en/Reference/ToneFrequencies of Musical Notes: http://www.phy.mtu.edu/~suits/notefreqs.html This series of articles aim at evaluating NBIS biometric software by using it against fingerprint image databases from FVC2004 verification competition.1. Contextualization matters1.1. First of all, what is NBIS?NBIS, which is an acronym for NIST Biometric Image Software [1], is a biometric software distribution developed by the National Institute of Standards and Technology (NIST) for the Federal Bureau of Investigation (FBI) and the Department of Homeland Security (DHS).The NBIS software bundle provides a collection of application programs, utilities, and source code libraries. It is organized in two categories: i) non-export controlled and ii) export controlled.The non-export controlled NBIS software is comprised of five major packages:PCASYS: a neural network based fingerprint pattern classification system;MINDTCT: a fingerprint minutiae detector;NFIQ: a neural network based fingerprint image quality algorithm;AN2K7: a reference implementation of the ANSI/NISTITL 1-2000 "Data Format for the Interchange of Fingerprint, Facial, Scar Mark & Tattoo (SMT) Information" standard; andIMGTOOLS: a collection of image utilities, including encoders and decoders for Baseline and Lossless JPEG and the FBI's WSQ specification.The export controlled NBIS software is organized into two major packages:NFSEG: a fingerprint segmentation system useful for segmenting four-finger plain impressions; andBOZORTH3: a minutiae based fingerprint matching system.NIST software is publicly available for download [2] and it is apparently continuously developed to present days. Its last version, 5.0.0, was released in April of 2015.1.2. Second, what is FVC2004?The Fingerprint Verification Competition (FVC) is an international competition focused on fingerprint verification software assessment [3]. A subset of fingerprint impressions acquired with various sensors was provided to registered participants, to allow them to adjust the parameters of their algorithms. Participants were requested to provide enroll and match executable files of their algorithms; the evaluation was conducted at the organizers' facilities using the submitted executable files on a sequestered database, acquired with the same sensors as the training set.These events received great attention both