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Built-in project · BBC micro:bit V2

micro:bit blink

A heart beating on the micro:bit's LED matrix, the board's own blink. The whole build, a BBC micro:bit, runs here in your browser on the firmware below; open it in the editor to change the wiring or the code and run it again.

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micro:bit blink · BBC micro:bit V2live0.000 s 0.00x
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The circuit itself, running here on the simulator. Press what can be pressed; click anything else to open it in the editor.

The code

The firmware exactly as the editor opens it. Change a line there and press Run: it compiles in the browser.

sketch.ino · BBC micro:bit V2
// Blink: a heart beating on the LED matrix.
//
// The micro:bit has no single LED to blink, so this blinks all of them at
// once: a big heart, then a small one, twice a second. showLeds() takes the
// picture as five rows of five, # for a lit LED and . for a dark one; the
// spaces are only there so the rows look like the picture.
//
// Underneath, the runtime scans the matrix a row at a time from the SysTick
// interrupt, driving each row's pin high and the columns of its lit LEDs low,
// which is how the real board lights 25 LEDs from ten pins. delay() parks the
// core on WFI between ticks, so this sketch costs the simulator almost nothing.

void setup() {
}

void loop() {
  showLeds(". # . # ."
           "# # # # #"
           "# # # # #"
           ". # # # ."
           ". . # . .");
  delay(500);
  showLeds(". . . . ."
           ". # . # ."
           ". # # # ."
           ". . # . ."
           ". . . . .");
  delay(500);
}

Parts list

1 part, plus the jumper wires. Every one is in the editor's parts bin.

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