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Built-in project · Wemos D1 R32

D1 R32 button

A button on the Wemos D1 R32’s D2 hole, which is GPIO 26, lights an LED on D3, GPIO 25, and the blue LED on GPIO 2. The whole build, a Wemos D1 R32 and 3 more parts, 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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The parts retail for about $13.25. On Mokxi they're free.

D1 R32 button · Wemos D1 R32live0.000 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 · Wemos D1 R32
// Button: the Uno's numbers are not the pins' numbers on a D1 R32.
//
// The hole printed D2 is GPIO 26 and the hole printed D3 is GPIO 25, so the
// sketch says 26 and 25. digitalWrite(2, ...) would be the blue LED on GPIO 2,
// which is the A0 hole, not D2.

const int kButton = 26; // D2, to GND
const int kLed = 25;    // D3, an LED and a resistor to GND

void setup()
{
    pinMode(kButton, INPUT_PULLUP);
    pinMode(kLed, OUTPUT);
    pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
    bool pressed = digitalRead(kButton) == LOW;
    digitalWrite(kLed, pressed ? HIGH : LOW);
    digitalWrite(LED_BUILTIN, pressed ? HIGH : LOW);
    delay(10);
}

Parts list

5 parts, plus the jumper wires. They retail for about $13.25; on Mokxi they're free.

How it is wired

4 connections, pin by pin, read from the circuit itself. Each line is one set of pins joined together, by a jumper wire or a breadboard strip.

  • Wemos D1 R32 pin IO25; Resistor, 220 Ω pin 1
  • Wemos D1 R32 pin IO26; Pushbutton pin 1a
  • Ground: Wemos D1 R32 pin GND; Pushbutton pin 2b; LED, green pin C
  • Resistor, 220 Ω pin 2; LED, green pin A

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