user18874: I've made a home-made Arduino based on this video. The problem is that I can't upload anything, it doesn't react, only the LED double blinks in every second. What does that mean? How to fix it? Thanks.
Update:


user10794: It's a reasonably clear photo (another couple would help) however I do see at least one major problem. Pin 8 (and pin 22) are Ground, but I don't see any wires running to that. Also the 22 pF (or similar) capacitors connected to the crystal should have their other sides grounded.
I suggest you look at my page Breadboard Arduino which has clear photos and wiring guides. In particular:

Notice the ground wire, and how the capacitors are connected.
I suggest you double-check all wiring, and make sure it is very similar to this:


18874: <p>I've made a home-made Arduino based on <a href="https://www.youtube.com/watch?v=sNIMCdVOHOM" rel="nofollow noreferrer">this video</a>. The problem is that I can't upload anything, it doesn't react, only the LED double blinks in every second. What does that mean? How to fix it? Thanks.</p>

<p>Update:
<a href="https://i.stack.imgur.com/REGTX.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/REGTX.jpg" alt="photo"></a></p>
 10794: <p>It's a reasonably clear photo (another couple would help) however I do see at least one major problem. Pin 8 (and pin 22) are Ground, but I don't see any wires running to that. Also the 22 pF (or similar) capacitors connected to the crystal should have their other sides grounded.</p>

<p>I suggest you look at my page <a href="http://www.gammon.com.au/breadboard" rel="nofollow noreferrer">Breadboard Arduino</a> which has clear photos and wiring guides. In particular:</p>

<p><a href="https://i.stack.imgur.com/mZ4n8.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mZ4n8.jpg" alt="Minimal Arduino"></a></p>

<p>Notice the ground wire, and how the capacitors are connected.</p>

<p>I suggest you double-check all wiring, and make sure it is very similar to this:</p>

<p><a href="https://i.stack.imgur.com/pIXMx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pIXMx.png" alt="Atmega328P wiring"></a></p>
