LED Blink

Solving Approach

I plan to create the code,  do the math to have the needed R, gather the materials

and then put it all together.

Code

/*Paste your code here*/

#define LEDPIN 13
void setup(){
	pinMode(LEDPIN, OUTPUT);
}

void loop(){
	digitalWrite(LEDPIN, HIGH);
	delay(400);
	digitalWrite(LEDPIN, LOW);
	delay(800);
}

Using Ohm's law, the resistance R must have a value of 500 Ohms.

Apparently 500 Ohm resistors are really rare, so I had to put in series

2 220 ohm resistors and 6 10 ohm resistors, to add up the 500 ohm

My Arduino UNO is doing busy with another project, cannot use now.

I Will show now a picture of an equivalent solution, using Arduino Nano.

Side note: I wasted around 20 minutes of my life, trying to debug with a dead arduino Nano, fortunately they are cheap, hence I have two. xD