Accessability: Add an external mouse-button to a Touchpad - Page 1
Forum section: electronics / projects

author: sirtet
author_rank: Contributor
timestamp: June 18, 2024, 02:00:07 pm
content: So...Someone with disabilities wants to control computers.Touching and dragging on a touchpad works, but clicking not so much.There's not enough control to work with tap-to-click. The mouse always shifts when attempting to click.So, the idea is to add an external button. Then ues one hand for touch-operation, one for the button...(Now, one can carefully position the mouse, get the hand off the pad, and click.)Add a button? How hard can it be? Solder 2 wires, done...Or so i thought, and bought a used apple magic trackpad for cheap.Because it was available, looks great, has a rather big surface and no space is used for the buttons which i will not use anyways.Teardown is easy,https://de.ifixit.com/Teardown/Magic+Trackpad+Teardown/3395Mechanical wizardry is stunning, as usual... (check out how the metal bar transfers the click-force to one corner, and the screw in that bar which is used to adjust the click-sensitivity)First, i got nervous about where to solder to, the connector seems to be the only option... less than ideal for soldering.After figuring out where the contacts go and what switching does (switch from around 400k to 1k), i ran into a wall:The pad is apparently smarted up, to only register clicks if there's a finger registered on the pad......So, what next? What would you do?Look for a dumber padI guess apple is the only overly-smart pad. I guess it has to do with having no surface for dedicated buttons (the pad itself is the button-cap, the upside-down button is activated by the rubber-feet being pushed into it (with this crazy metal-bar making the transfer from the left foot to the button on the right.Add a 2nd bluetooth mouse, use only the button(s) of that.Pro: a wireless button is helpful in daily use. Con: having to check 2 bt-connections begs for more confusion/trouble in long-term, 2 sets of batteries are more cumbersome.More ideas?

author: tooki
author_rank: Super Contributor
timestamp: June 18, 2024, 05:37:53 pm
content: Yeah you could have saved yourself a lot of trouble by researching (and/or thinking about) the Magic Trackpad ahead of time, since it indeed uses finger position (and count, IIRC) as part of interpreting a click. These days, some trackpads in laptops work similarly, using tact switches only to detect that the trackpad is being clicked, but using finger position to interpret what kind of click to output.Incidentally, the reasoning behind rejecting a click when there is no finger present is sound: it prevents unwanted clicking if, for example, you have another pointing device and forget about the trackpad, and lay down a book or something that accidentally presses it down.I would get another mouse (can also be USB, doesn’t have to be Bluetooth) and modify that as the clicker. As you already know, there is absolutely nothing that says that one needs to click with the same device used to move the pointer — it’s absolutely no problem to have multiple pointing devices at the same time. (In fact, on the Mac, one of my favorite ways to work is two-handed, using a mouse with my right hand to move the pointer and click, and a Magic Trackpad with my left hand to scroll. It’s way, way more natural and intuitive than one might think.)One last thought: if you’re using this on a Mac, macOS has accessibility features to support external switches. You could get an off-the-shelf one and configure the switch options to use it to click.

author: Gribo
author_rank: Frequent Contributor
timestamp: June 18, 2024, 07:45:43 pm
content: There are USB buttons and foot pedals, if that works for you. Anywhere from a single key device to a full blown emergency stop with lights and sounds.

author: sirtet
author_rank: Contributor
timestamp: June 24, 2024, 07:56:55 am
content: Thanks guys.No, USB won't do, i need to go wireless to an iPad.I think i will go with a 2nd BT Mouse for the buttons and live with the hassle-potential of having to connect 2 devices.Also researched some ESP DIY options.If an emulated BT "mouse" operated by buttons is acceptable (it's not for me), it looks easy:https://youtu.be/2HgB7K4SpesForwarding the input from another touchpad would surely be a lot more work, out of my scope.Also, if u want to connect a USB Mouse & Keyboard via BT, Aliexpress has a lot of BT Hubs that can even switch the inputs between multiple BT hosts.

author: tooki
author_rank: Super Contributor
timestamp: June 24, 2024, 09:20:59 pm
content: There are off-the-shelf products for this type of situation:https://enablingdevices.com/product/ipad-wireless-switches/Pairing multiple devices is no big deal, you only have to pair each device once. After that you just switch them on.