user45371: 
Hello
My serial monitor keep showing these unreadable characters. Anyone know what is going on? Many thanks!





user31105: It can have many reasons, but the most likely are:

You set the baudrate wrong
You set the stop/start bits wrong
You send wrong data
The cable is bad

It helps if you show your sketch(es), for sender/receiver and possibly your circuit.

45371: <p><a href="https://i.stack.imgur.com/6Ljd6.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6Ljd6.jpg" alt="enter image description here"></a></p>

<p>Hello</p>

<p>My serial monitor keep showing these unreadable characters. Anyone know what is going on? Many thanks!</p>

<p><a href="https://i.stack.imgur.com/njNXd.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/njNXd.jpg" alt="Schematic"></a>
<a href="https://i.stack.imgur.com/hL2LB.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hL2LB.jpg" alt="Physical"></a>
<a href="https://i.stack.imgur.com/y0NPK.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/y0NPK.jpg" alt="Physical2"></a></p>

<hr>
 31105: <p>It can have many reasons, but the most likely are:</p>

<ul>
<li>You set the baudrate wrong</li>
<li>You set the stop/start bits wrong</li>
<li>You send wrong data</li>
<li>The cable is bad</li>
</ul>

<p>It helps if you show your sketch(es), for sender/receiver and possibly your circuit.</p>
