C-Command Software Forum

ToothFairy use case: Sharing a Magic Trackpad between multiple Macs

Hi all,

Thanks to the wonderful ToothFairy I am able to conveniently share an Apple Magic Trackpad between three MacBooks! These are normally used as mobile devices, but when working at the desk a separate keyboard and trackpad are preferred. I already got a Bluetooth keyboard, a Logitech K760, that can be paired with three devices and has three dedicated keys to switch between them. Now I had to find a way how to accomplish the same with my Magic Trackpad.

As it turns out, the Apple Magic Trackpad is able to be paired with multiple computers (and possibly iPads) and will remember these pairings. It can — however and of course — only be connected to a single one at the same time and will automatically connect to the last one used, and when connected it does no longer present itself for pairing. So in order to be able to pair it with another computer, just turn Bluetooth off on all the other ones, and the Magic Trackpad will appear in the Bluetooth device list as a newly available device.

After having been paired to all devices, the remaining problem is how to make the trackpad switch between them. As soon as it is connected to one, it will just ignore connection requests coming from the others. So it needs to be disconnected first.

This is where ToothFairy comes in to make this process easy and convenient. I added the trackpad to all computers so that an icon appears in the menu bar which shows the connection state and which can be clicked to connect and disconnect. Of course clicking the icon does not work so well without a pointing device, so I assigned a keyboard shortcut. Whenever I want to work with one of the MacBooks, I connect it to the external monitor and press the dedicated key on my multi-pairable bluetooth keyboard for the respective machine, which will cause the keyboard to establish the Bluetooth connection and wake it up. Then I enter my login password and press Shift+Control-Alt-T to have ToothFairy connect the trackpad. Voilà!

I just wanted to share this here in case someone might find it useful or inspiring.


I’m thrilled to find this post as I’ve been trying to figure out how to do the same (share Trackpad).

I’ve setup the Magic Trackpad within Bluetooth settings on both of my Macs (iMac and MacBook Pro). Unfortunately, unless I turn off Bluetooth entirely on the Mac I’m moving from, the Mac I’m moving to will not connect to the trackpad via Bluetooth settings.

I can successfully disconnect the Trackpad via bluetooth settings on the Mac I’m moving from, but the Mac I’m moving to will not connect.

I realize this is outside of Toothfairy. But, if I can’t resolve the inherent bluetooth functions, I can’t take advantage of TF.

Any troubleshooting tips? thanks – jay

btw, both Macs are running Catalina

Are you already using ToothFairy, or are you for now only trying this with just the base OS functions to see whether it works at all before spending the money?

I am asking because I did only try this with TF and not without. Maybe TF does do things still a bit different from what the Bluetooth menu functions do?

I already own TF.

I had never thought about TF as an option for my need as in my mind I equated TF to just an AirPod utility!

OK, let’s see. This is what I have here:

  1. MacBook Air 13" 2013 with High Sierra 10.13.6 using the built-in LCD screen
  2. MacBook Pro 15" 2016 with Mojave 10.14.6, connected to external display, lid closed
  3. MacBook Pro 13" 2019 with Catalina 10.15.6 using the built-in LCD screen
  4. Apple Magic Trackpad Model A1339, paired with all three
  • Trackpad connected to 2.; I press my TF shortcut Shift-Control-Alt-T, Trackpad disconnects from 2. which is reflected in the TF icon for it, and the mouse pointer does no longer move
  • I press my TF shortcut Shift-Control-Alt-T on 3., trackpad gets connected there (icon changes, pointer on 3. movable with trackpad)
  • I press Shift-Control-Alt-T on 3. to disconnect trackpad which is properly reflected in the TF icon and the mouse pointer does no longer move
  • I press Shift-Control-Alt-T on 2., TF icon on 2. indicates a connected trackpad and it works as expected
  • I press Shift-Control-Alt-T on 2., TF icon on 2. indicates a disconnected trackpad
  • I press Shift-Control-Alt-T on 1., TF icon on 1. indicates a connected trackpad, trackpad works

…and so on. The Catalina machine has no problems neither letting the trackpad go nor reacquiring it.

(Of course I need to disconnect the trackpad first before it will connect to some other machine; if I forget to disconnect it, I will eventually get a popup window telling me about a connection timeout.)

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Thanks for all of the detail. My setup is Mac 1 and Mac 2. Here’s what is repeatable for me:

Trackpad setup successfully in bluetooth settings on both Mac 1 and Mac 2. If I turn off bluetooth on Mac 1, the trackpad will connect to Mac 2. If I turn off bluetooth on Mac 2, the trackpad will connect to Mac 1. That works as I would expect.

Now, assume trackpad is connected to Mac 1. If I use my Toothfairy shortcut on Mac 1 to connect/disconnect the Trackpad, it works as expected: If use the shortcut on Mac 1 to disconnect, the trackpad disconnects from Mac 1. If I then use the shortcut on Mac 1 to connect, the trackpad connects to Mac 1. That works as I would expect.

Now, here’s where the problem occurs. If I use the Toothfairy shortcut on Mac 1 to disconnect, the trackpad disconnects. If I then use the Toothfairy shortcut on Mac 2 to connect, the Toothfairy icon flashes connected briefly then returns to a disconnected state. If I watch the bluetooth pref panel on Mac 2, I see the same behavior. Brief indication of connected and then immediately disconnects with a “can’t connect” error.

At that point, the only way I can get the Trackpad recognized on Mac 2 is by turning off Bluetooth entirely on Mac 2. Once I do that, I can connect to Mac 2.

But then, the reverse is true. If I disconnect on Mac 2 and then go to Mac 1 and try to connect, the same thing occurs. Connection fails on Mac 1.

So… problem is repeatable on either side. I realize this is not a Toothfairy issue. For some reason, apple bluetooth is not able to re-establish the connection when it is relinquished by the other Mac.

Do you also have the A1339 Trackpad model?
Do you also run Catalina 10.15.6?

I am not an expert regarding macOS & Bluetooth (for me Bluetooth always has “mostly worked”), but what I’d do would be to try whether the problem persists in a freshly created, otherwise empty new user environment. I.e. create a new user e.g. named “test” on both machines, reboot both machines and only login to this test user which, being new, won’t have a lot of tools and background apps started. This might help to find out whether there is some other tool which you are running on both of your Macs which interferes.

And can we perhaps summon @Michael_Tsai or some other expert by just quoting his name? Let’s try. :wink:

Edit: Another thing, probably also unrelated: Do you happen to use a 2.4GHz WiFi? The frequency ranges of 802.11b/g/n and Bluetooth overlap, sometimes causing problems. Does this also happen on 5GHz 802.11ac or with WiFi turned off?

Trackpad is Apple Magic Trackpad 2

iMac is 10.15.5
MacBookPro is 10.15.6

Wifi is 802.11ac

I may fiddle a bit more, but for now… I will just leave 2 trackpads on my desk! :slight_smile:

I would expect what you’re doing to work, so all I can really suggest is some general troubleshooting. As @Arndt says, make test user accounts or perhaps do a safe boot of both Macs. The Wi-Fi suggestions are good. There are some additional suggestions here.

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Could it be that this is the sole reason? Does the Magic Trackpad 2 do things differently?

It would be cool if other owners of an Apple Magic Trackpad of either version could chime in. I only have the original A1339, which does work fine, and nobody to borrow a Trackpad 2 from.

Thank you both. I was able to get it to work as expected using an older original Trackpad. So, yes @Arndt, perhaps there is something unique about either the Trackpad 2 or my setup.

I appreciate your input and ideas. – jay

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