DocsOpen the editorEditor
Built-in project · ATtiny85

ATtiny85 dimmer

A knob on PB2 dims an LED on PB0, out of an eight-pin chip in the breadboard. No board, no USB, just the chip and its two rails. The whole build, an ATtiny85 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.

Open in the editorRead the code

IntermediateRuns in your browser. Free, and no account needed.

ATtiny85 dimmer · ATtiny85live0.000 s 0.00x
Click to open it in the editor
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 · ATtiny85
// Knob dimmer: a potentiometer on PB2 (A1, package pin 7) sets the
// brightness of an LED on PB0 (pin 5).
//
// The pot's two ends go to VCC and GND and its wiper to PB2, so turning it
// sweeps the pin from 0 V to the supply. analogRead gives 0..1023 against VCC
// and analogWrite takes 0..255, so the reading is shifted down by two.
//
// PB0 is OC0A: timer 0's compare output, the same timer that counts
// milliseconds, at 488 Hz. The LED is dimmed by the hardware, not by the
// sketch, so the loop is free to do nothing for 20 ms between readings.

void setup()
{
    pinMode(0, OUTPUT);
}

void loop()
{
    int reading = analogRead(A1);

    analogWrite(0, reading >> 2);
    delay(20);
}

Parts list

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

How it is wired

5 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.

  • 5 V: Potentiometer pin 3; ATtiny85 pin RESET; ATtiny85 pin VCC
  • Ground: Potentiometer pin 1; ATtiny85 pin GND; LED, amber pin C
  • Potentiometer pin 2; ATtiny85 pin PB2
  • ATtiny85 pin PB0; Resistor, 220 Ω pin 1
  • Resistor, 220 Ω pin 2; LED, amber pin A

Change it and keep it

Open it in the editor, change the circuit or the code, and keep your version in a free account.

Create a free account
Open it in the editor