user11714: I saw this answer but I can't find the analog for Mac.
I've tried cycling thru keycodes from 0x01 thru maybe 0x500, and I went thru ascii a few times, also found brightness up/down, and F11, F12, but they get pressed with fn key by default which makes them do operations other than vol +/-.

user6424: Unfortunately, Fn is hardware and it is handled internally by the keyboard to do something hardware-based without sending any code. So the short answer is: you can't simulate Fn key with arduino.
What I think of as a solution is:

Create a program on your Mac that can listen for keyboard scan codes to do vol +/- or any other function.
Send a custom scan code from Arduino to your Mac ( a scan code that isn't part of the standard scan codes ).
When your listening program receives that code, it should do Vol +/- (or anything else )...


user14589: Could you just untick the "Use all F1, F2, …" in System Preferences -> Keyboard?

Just wondering if that would be an option and if doing so would create the desired outcome.

11714: <p>I saw <a href="https://arduino.stackexchange.com/questions/8934/send-keyboard-media-keys-with-keyboard-library">this answer</a> but I can't find the analog for Mac.</p>

<p>I've tried cycling thru keycodes from 0x01 thru maybe 0x500, and I went thru ascii a few times, also found brightness up/down, and <code>F11</code>, <code>F12</code>, but they get pressed <strong>with fn key by default</strong> which makes them do operations other than vol +/-.</p>
 6424: <p>Unfortunately, <code>Fn</code> is hardware and it is handled internally by the keyboard to do something hardware-based without sending any code. So the short answer is: you can't simulate Fn key with arduino.</p>

<p>What I think of as a solution is:</p>

<ul>
<li>Create a program on your Mac that can listen for keyboard scan codes to do vol +/- or any other function.</li>
<li>Send a custom scan code from Arduino to your Mac ( a scan code that isn't part of the standard scan codes ).</li>
<li>When your listening program receives that code, it should do Vol +/- (or anything else )...</li>
</ul>
 14589: <p>Could you just untick the "Use all F1, F2, …" in System Preferences -> Keyboard?</p>

<p><a href="https://i.stack.imgur.com/MHk0S.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/MHk0S.png" alt="enter image description here"></a></p>

<p>Just wondering if that would be an option and if doing so would create the desired outcome.</p>
