Plug in your NeoMatrix Mk I to your computer over USB.
Before going any further, make sure you have a basic understanding of how to program and use an Arduino. Thankfully, we have a lot of great tutorials on how this whole thing works. Click here to get started with Arduino, and then come back to this guide to continue.
Board Manager
To use the Metro board in Arduino, check the Arduino IDE Tools > Board list and select Adafruit Metro. Note: if you don't see the Metro on that list, add this URL to your Arduino > Preferences > Additional Boards Manager URLs: https://adafruit.github.io/arduino-board-index/package_adafruit_index.json
Then, go to the Arduino > Tools > Board > Boards Manager... and type 'metro' in the search, then install the Adafruit AVR Boards package.
Now, pick the Adafruit Metro board from the Arduino > Tools > Board list.
Keypad
To use the 3x4 matrix keypad, you'll need to get a library that adds this functionality to your Metro. Click Arduino > Sketch > Include library... > Manage Libraries, then type 'arduino keypad' in the search box. Install the library shown here.
NeoSegment
Finally, you'll need to install the NeoSegment library. This makes it easy to program the displays without needing to make calls to the individual NeoPixels behind the segments. This higher level library abstracts things into digits and segments, so you can tell, say, the first digit to display a '4' and the second digit to display an 'A'.
Check out the documentation on NeoSegments here. Then, install the library as explained and provided here. Once you've gotten the basic demo examples working, return here.
Coding
Now, you're ready to code the NeoMatrix Mk I. Copy the code below, then past it into a new Arduino document. Save the file to your Arduino project directory as neoMatrixMkI.ino, then upload it to the board.
// SPDX-FileCopyrightText: 2017 John Park for Adafruit Industries
//
// SPDX-License-Identifier: MIT
#include "Arduino.h"
#include "Keypad.h"
#include "Neosegment.h"
#include <stdlib.h>
#define SERIAL_BAUD 115200
#define nDigits 6 // number of digits in display
#define NEOSEGPIN 12
#define LEDbrightness 255 // 0 to 255
/*
Segment mapping
5
___
4 | | 6
|___|
| 3 |
0 |___| 2
1
*/
int buttonPin = 11; //pushbutton
int ledPin = 13; // select the pin for the LED
int knobUpperPin = A3; // input pin for a potentiometer
int knobLowerPin = A2; // input pin for a potentiometer
int knobUpper = 0; // variable to store the value coming from the sensor
int knobLower = 0; // variable to store the value coming from the sensor
int buttonState;
int lastButtonState = LOW;
long lastDebounceTime = 0;
long debounceDelay = 50;
//initialize the neosegment object
Neosegment neosegment(nDigits, NEOSEGPIN, LEDbrightness);
uint16_t i, j;
//set up the keypad
const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns
char keys[ROWS][COLS] = {
{'1','2','3'},
{'4','5','6'},
{'7','8','9'},
{'*','0','#'}
};
byte rowPins[ROWS] = {5, 6, 7, 8}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {2, 3, 4}; //connect to the column pinouts of the keypad
//initialize the keypad object
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
//use to set digit cursor position
int neoCounter = 0;
//gamma correction table
const uint8_t PROGMEM gamma8[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2,
2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 5,
5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10,
10, 10, 11, 11, 11, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 16,
17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 24, 24, 25,
25, 26, 27, 27, 28, 29, 29, 30, 31, 32, 32, 33, 34, 35, 35, 36,
37, 38, 39, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 50,
51, 52, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 66, 67, 68,
69, 70, 72, 73, 74, 75, 77, 78, 79, 81, 82, 83, 85, 86, 87, 89,
90, 92, 93, 95, 96, 98, 99,101,102,104,105,107,109,110,112,114,
115,117,119,120,122,124,126,127,129,131,133,135,137,138,140,142,
144,146,148,150,152,154,156,158,160,162,164,167,169,171,173,175,
177,180,182,184,186,189,191,193,196,198,200,203,205,208,210,213,
215,218,220,223,225,228,231,233,236,239,241,244,247,249,252,255 };
void setup(){
Serial.begin(SERIAL_BAUD);
pinMode(ledPin, OUTPUT);
pinMode(buttonPin, INPUT_PULLUP);
digitalWrite(ledPin, HIGH); //turn on the LED
neosegment.begin();
neosegment.clearAll();
for(int i = 0; i < 6; i++){ //turn on green lines, top row, L to R
neosegment.setSegment(i, 5, 0, 40, 0); //the '3' segment is middle dash
tone(A1, 330, 100);
delay(50);
}
neosegment.setSegment(5, 6, 0, 40, 0);
tone(A1, 330, 100);
delay(50);
neosegment.setSegment(5, 2, 0, 40, 0);
tone(A1, 330, 100);
delay(50);
neosegment.clearAll();
for(int i = 5; i > -1; i--){ //turn on green lines, bottom row, R to L
neosegment.setSegment(i, 1, 0, 40, 0); //the '3' segment is middle dash
tone(A1, 330, 100);
delay(50);
}
neosegment.setSegment(0, 0, 0, 40, 0);
tone(A1, 330, 100);
delay(50);
neosegment.clearAll();
for(int i = 0; i < 6; i++){ //turn on green lines, middle row, L to R
neosegment.setSegment(i, 3, 0, 40, 0); //the '3' segment is middle dash
tone(A1, 440, 100);
delay(100);
}
}
void loop(){
//read button
int buttonReading = digitalRead(buttonPin);
if (buttonReading != lastButtonState) {
lastDebounceTime = millis();
}
if ((millis() - lastDebounceTime) > debounceDelay){
buttonState = buttonReading;
}
Serial.println(buttonState);
if(buttonState){
digitalWrite(ledPin, LOW);
}
else{
digitalWrite(ledPin, HIGH);
}
lastButtonState = buttonReading;
//read knobs
knobUpper = analogRead(knobUpperPin); //used for hue
knobLower = analogRead(knobLowerPin); //used for value
//map knob range
int knobUpperMapped = map(knobUpper, 0, 700, 360, 0);
int knobLowerMapped = map(knobLower, 0, 700, 700, 0);
//constrain knob range
knobUpperMapped = constrain(knobUpperMapped, 0, 360);
knobLowerMapped = constrain(knobLowerMapped, 0, 700);
//map to hue range
//int knobHue = map(knobUpperMapped, 0, 255, 0, 360);
//knobHue = constrain(knobHue, 0, 360);
float knobHue = ((float)knobUpperMapped);
//map to value range
float knobValue = ((float)knobLowerMapped / 700);
float r, g, b;
float h = knobHue;
float s = 1.0;
float v = knobValue;
HSVtoRGB(&r, &g, &b, h, s, v); //convert HSV to RGB
uint8_t r_byte = (int)(r * 255);
uint8_t g_byte = (int)(g * 255);
uint8_t b_byte = (int)(b * 255);
//apply gamma correction table values
r_byte = pgm_read_byte(&gamma8[r_byte]);
g_byte = pgm_read_byte(&gamma8[g_byte]);
b_byte = pgm_read_byte(&gamma8[b_byte]);
char key = keypad.getKey();
if (key != NO_KEY){ // a key has been pressed
Serial.print("key: ");
Serial.println(key);
int neoKey = key - '0'; //terminate w zero so don't get ASCII code
//enter with '#'
if(key == '#'){
neosegment.clearAll();
delay(35);
neosegment.setSegment(5, 2, 40, 40, 40);
neosegment.setSegment(5, 6, 40, 40, 40);
delay(35);
tone(A1, 660, 100);
for(int i = 5; i > -1; i--){ //from right to left
neosegment.setSegment(i, 1, 40, 40, 40);
neosegment.setSegment(i, 5, 40, 40, 40);
delay(35);
tone(A1, 660, 100);
}
neosegment.setSegment(0, 0, 40, 40, 40);
neosegment.setSegment(0, 4, 40, 40, 40);
tone(A1, 660, 100);
neoCounter = 0;
//letters that appear in upper: A, E, F, H, I, J, L, P, S, U
//letters that appear in lower: b, c, d, g, n, o, q, r, t
delay(1000);
neosegment.clearAll();
delay(1000);
neosegment.setDigit(5, 'a', 23, 0, 12);
tone(A1, 220, 100);
delay(500);
neosegment.setDigit(4, 'a', 23, 0, 12);
neosegment.setDigit(5, 'c', 23, 0, 12);
tone(A1, 220, 100);
delay(500);
neosegment.setDigit(3, 'a', 23, 0, 12);
neosegment.setDigit(4, 'c', 23, 0, 12);
neosegment.setDigit(5, 'o', 23, 0, 12);
tone(A1, 220, 100);
delay(500);
neosegment.setDigit(2, 'a', 23, 0, 12);
neosegment.setDigit(3, 'c', 23, 0, 12);
neosegment.setDigit(4, 'o', 23, 0, 12);
neosegment.setDigit(5, 'r', 23, 0, 12);
tone(A1, 220, 100);
delay(500);
neosegment.setDigit(1, 'a', 23, 0, 12);
neosegment.setDigit(2, 'c', 23, 0, 12);
neosegment.setDigit(3, 'o', 23, 0, 12);
neosegment.setDigit(4, 'r', 23, 0, 12);
neosegment.setDigit(5, 'n', 23, 0, 12);
tone(A1, 220, 100);
delay(2000);
for(int x=0; x<50; x++){
neosegment.setDigit(2, 'c', 0, x, 0);
delay(15);
}
for(int x=0; x<50; x++){
neosegment.setDigit(4, 'r', x, x, 0);
delay(15);
}
for(int x=0; x<50; x++){
neosegment.setDigit(3, 'o', 0, x, x);
delay(15);
}
for(int x=0; x<50; x++){
neosegment.setDigit(5, 'n', x, 0, 0);
delay(15);
}
for(int x=0; x<50; x++){
neosegment.setDigit(1, 'A', x/2, x/2, x/2);
delay(15);
}
delay(500);
neosegment.setDigit(1, 'a', 23, 0, 12);
neosegment.setDigit(2, 'c', 23, 0, 12);
neosegment.setDigit(3, 'o', 23, 0, 12);
neosegment.setDigit(4, 'r', 23, 0, 12);
neosegment.setDigit(5, 'n', 23, 0, 12);
tone(A1, 220, 100);
delay(1700);
neosegment.clearAll();
delay(500);
for(int i = 0; i < 6; i++){ //turn on green lines, middle row, L to R
neosegment.setSegment(i, 3, 0, 40, 0); //the '3' segment is middle dash
//tone(A1, 440, 100);
delay(100);
}
}
//special function with '*'
else if(key == '*'){ //show HUE value
neosegment.clearAll();
neosegment.setDigit(0, 'h', 0, 30, 0);
neosegment.setDigit(1, 'u', 0, 30, 0);
neosegment.setDigit(2, 'e', 0, 30, 0);
int ones = (((int)knobHue) % 10);
int tens = ((((int)knobHue)/10) % 10);
int hundreds = ((((int)knobHue)/100) % 10);
neosegment.setDigit(5, ones, r_byte, g_byte, b_byte);
neosegment.setDigit(4, tens, r_byte, g_byte, b_byte);
neosegment.setDigit(3, hundreds, r_byte, g_byte, b_byte);
Serial.print("red byte: ");
Serial.println(r_byte);
tone(A1, ((knobHue+31)), 200);
neoCounter = 0;
}
//number keys
else{ // display numbers
if(neoCounter%6 == 0){ //clear when screen gets full
neosegment.clearAll();
}
int neoPosition = (neoCounter % 6); //use modulo operation to loop
//through the positions
int BLUE = knobUpperMapped;
neosegment.setDigit(neoPosition, neoKey, r_byte, g_byte, b_byte);
neoCounter++;
tone(A1, ((knobUpperMapped * neoKey) + 31), 170); //+31 deals with
//the 0 key
}
}
}
//function to convert Hue, Saturation, Value to Red, Green, Blue
void HSVtoRGB(float *r, float *g, float *b, float h, float s, float v){
//HSV is in HUE: degrees, SATURATION: 0 to 1.0, VALUE: 0 to 1.0
int i;
float f, p, q, t;
if( s == 0 ) {
// achromatic (grey)
*r = *g = *b = v;
return;
}
h /= 60; // sector 0 to 5
i = floor( h );
f = h - i; // factorial part of h
p = v * ( 1 - s );
q = v * ( 1 - s * f );
t = v * ( 1 - s * ( 1 - f ) );
switch( i ) {
case 0:
*r = v;
*g = t;
*b = p;
break;
case 1:
*r = q;
*g = v;
*b = p;
break;
case 2:
*r = p;
*g = v;
*b = t;
break;
case 3:
*r = p;
*g = q;
*b = v;
break;
case 4:
*r = t;
*g = p;
*b = v;
break;
default: // case 5:
*r = v;
*g = p;
*b = q;
break;
}
}
You can see from the code that there are a few different functions, depending on which buttons you press.
- The number keys will display numbers and play beeps, which differ in pitch depending on the digit. Also, turn the upper knob to change which hue will be used the next time you press a number. The bottom knob adjusts value/brightness
- Press the '*' key to see the hue value expressed as a number from 0-360 on a color wheel
- Press the '#' key to "enter" your code. This is just a demo mode, so all answers are correct and lead to a short reveal of a new code word. Look at how this was written to adjust for your own needs
Page last edited January 21, 2025
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