Lesson 1 of 7

Blink an LED

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// Blink an LED on pin 13 (the L LED blinks along) // R1 = 1000 ohms: LED current = (5 V - 2 V) / R1, and an R4 pin allows 8 mA const int LED_PIN = 13; // the L LED is on pin 13 too const int WAIT_MS = 500; void setup() { pinMode(LED_PIN, OUTPUT); // pin 13 drives the LED } void loop() { digitalWrite(LED_PIN, HIGH); delay(WAIT_MS); digitalWrite(LED_PIN, LOW); delay(WAIT_MS); }

Stopped · Your code isn't running yet. Until you press Run, the board runs the program already on it.

Nothing printed yet. Press Run.

An LED and a resistor on D13, the same pin as the board's L LED. Change the delay and the resistor, and see why an R4 pin wants a bigger resistor than an R3 pin.

The L LED on the board blinks with yours
8 mA per pin: pick the resistor with care
Change the delay and watch the period follow

Pin	Connects to	What it does
`D13`	The resistor, then the LED's long leg	Switches the LED: HIGH lights it.
`GND`	The LED's short leg	Where the current goes back to.

Wire it in

Sensors and actuators this board drives, with the real connections.

LEDSupply 5 V
Long leg (anode) through a 1 kΩ resistor to D13, short leg to GND. 1 kΩ gives about 3 mA, well inside the R4's 8 mA per pin.
Part pin Board pin
A D13Wire colour orange
K GNDWire colour black
Careful
Never without a resistor: an R4 pin is good for 8 mA, and a bare LED would try to pull far more.

Part pin	Board pin
A	D13Wire colour orange
K	GNDWire colour black

All 6 parts on the Arduino UNO R4 page

Blink an LED

Try it yourself

Serial monitor

Checks

Break it

Parameters

Wire it in

Blink an LED

Try it yourself

Serial monitor

Checks

Break it

Parameters

Wire it in