micro bit

In a previous article we looked at the scroll:bit, this is an add on from Pimoroni which contains a lot of LEDs, in fact there are 119 in total in a 17 x 7 matrix – its controlled by a IS31FL3731 LED matrix driver chip. This is what the add on looks like plugged into a micro:bit

The examples were all created in the makecode editor and there is also a python library. A search on the internet revealed that Adafruit had a similar piece of hardware and an arduino library. We will see if we can get the arduino examples to work

Code

You need to to install the Adafruit_GFX and Adafruit_IS31FL3731 libraries, you can add these using the library manager.

The key thing is that the Featherwing version is the same size as the scroll:bit. So in the code you need to use

Adafruit_IS31FL3731_Wing ledmatrix = Adafruit_IS31FL3731_Wing();

These 2 examples work fairly well

[codesyntax lang=”cpp”]

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_IS31FL3731.h>

// If you're using the full breakout...
//Adafruit_IS31FL3731 ledmatrix = Adafruit_IS31FL3731();
// If you're using the FeatherWing version
Adafruit_IS31FL3731_Wing ledmatrix = Adafruit_IS31FL3731_Wing();


// The lookup table to make the brightness changes be more visible
uint8_t sweep[] = {1, 2, 3, 4, 6, 8, 10, 15, 20, 30, 40, 60, 60, 40, 30, 20, 15, 10, 8, 6, 4, 3, 2, 1};

void setup() {
  Serial.begin(9600);
  Serial.println("ISSI swirl test");

  if (! ledmatrix.begin()) {
    Serial.println("IS31 not found");
    while (1);
  }
  Serial.println("IS31 found!");
}

void loop() {
  // animate over all the pixels, and set the brightness from the sweep table
  for (uint8_t incr = 0; incr < 24; incr++)
    for (uint8_t x = 0; x < 16; x++)
      for (uint8_t y = 0; y < 9; y++)
        ledmatrix.drawPixel(x, y, sweep[(x+y+incr)%24]);
  delay(20);
}

[/codesyntax]

and now for the second example

[codesyntax lang=”cpp”]

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_IS31FL3731.h>

// If you're using the full breakout...
//Adafruit_IS31FL3731 matrix = Adafruit_IS31FL3731(17,7);
// If you're using the FeatherWing version
Adafruit_IS31FL3731_Wing matrix = Adafruit_IS31FL3731_Wing();

static const uint8_t PROGMEM
  smile_bmp[] =
  { B00111100,
    B01000010,
    B10100101,
    B10000001,
    B10100101,
    B10011001,
    B01000010,
    B00111100 },
  neutral_bmp[] =
  { B00111100,
    B01000010,
    B10100101,
    B10000001,
    B10111101,
    B10000001,
    B01000010,
    B00111100 },
  frown_bmp[] =
  { B00111100,
    B01000010,
    B10100101,
    B10000001,
    B10011001,
    B10100101,
    B01000010,
    B00111100 };


void setup() {

  Serial.begin(9600);
  Serial.println("ISSI manual animation test");
  if (! matrix.begin()) {
    Serial.println("IS31 not found");
    while (1);
  }
  Serial.println("IS31 Found!");
  
}


void loop() {
  matrix.setRotation(0);

  matrix.clear();
  matrix.drawBitmap(3, 0, smile_bmp, 8, 8, 255);
  delay(500);
  
  matrix.clear();
  matrix.drawBitmap(3, 0, neutral_bmp, 8, 8, 64);
  delay(500);

  matrix.clear();
  matrix.drawBitmap(3, 0, frown_bmp, 8, 8, 32);
  delay(500);

  matrix.clear();
  matrix.drawPixel(0, 0, 255);  
  delay(500);

  matrix.clear();
  matrix.drawLine(0,0, matrix.width()-1, matrix.height()-1, 127);
  delay(500);

  matrix.clear();
  matrix.drawRect(0,0, matrix.width(), matrix.height(), 255);
  matrix.fillRect(2,2, matrix.width()-4, matrix.height()-4, 20);
  delay(500);

  matrix.clear();
  matrix.drawCircle(8,4, 4, 64);
  matrix.drawCircle(8,4, 2, 32);
  delay(500);


  matrix.setTextSize(1);
  matrix.setTextWrap(false);  // we dont want text to wrap so it scrolls nicely
  matrix.setTextColor(100);
  for (int8_t x=0; x>=-32; x--) {
    matrix.clear();
    matrix.setCursor(x,0);
    matrix.print("Hello");
    delay(100);
  }

  matrix.setTextSize(2);
  matrix.setTextWrap(false);  // we dont want text to wrap so it scrolls nicely
  matrix.setTextColor(32);
  matrix.setRotation(1);
  for (int8_t x=7; x>=-64; x--) {
    matrix.clear();
    matrix.setCursor(x,0);
    matrix.print("World");
    delay(100);
  }
}

[/codesyntax]